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J ’ figfi: 1; 1‘“; - I §~A i {5?} as ”f a' L; -o TX :1 ; ‘iffi’hi.~?v;af A. 43:113.)” 4 ..‘ Tiff-t; if); ; p 7!”; 05, :2» 03 ’31 “)1. a, . . V ' ' ~. ‘3‘.)‘, .7‘ :- . 392%; o: -L-fiib'C/r; 1 g; v p.. .‘ . 4- ' {4%. Wk§h¢fiq 3'25 Ra's-ask . If]; .' ; 4 lg: ‘11! I. ;.3';‘ A( I; :2};£?v.fit .‘ c: 1“?“ lemma sure um,“ 1171111121111/ Ill/II/llllIl/I/l/II/l/ sill/£0735 1706’ any momma: § \ l/ll/ll III "I I". This is to certify that the dissertation entitled The Bionomics of Acarina Associated With Selected Turfgrasses presented by Saad ELSayed Salem has been accepted towards fulfillment of the requirements for Ph.D. Zoology degree in / / [A 4/1 I ’ (/AI'A/AJ ajorp .fessor ‘\ 1 Date 10/12/1989 MS U is an Affirmative Action/Equal Opportunity Institution 042771 h‘ F LIBRARY I Michigan State ‘ University 1‘ PLACE IN RETURN BOX to remove We checkout irom your record. TO AVOID FINES retun on or before due due. DATE DUE DATE DUE DATE DUE — l:_" __:§ MSU le An Afflrmdive ActioNEquel Opportunity Inethion cWMt THE BIONOMICS OF ACARINA ASSOCIATED WITH SELECTED TURFGRASSES By Saad ELSayed Salem A DISSERTATION Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Zoology 1989 l/\ p/L’Tdv) ABSTRACT THE BIONOMICS OF ACARINA ASSOCIATED WITH SELECTED TURFGRASSES BY Saad ELSayed Salem The present study assessed population density, seasonal fluctuation, and vertical distribution of selected genera and species of Acarina inhabiting the soil under six species of turfgrass. During both study years (1985 and 1986) Acarina were the dominant soil artheopods. Within Acarina, Prostigmata were most numerous, followed by Mesostigmata; Cryptostigmata ranked third and Astigmata fourth. Data obtained on several of the most abundant genera and species were subjected to detailed analyses. Results indicated distinct differences between the studied taxa. While some showed no preference for either of the sampled strata (0-15 and 16-30 cm depth), Enpgggg spp. for instance were clearly upper horizon dwellers. Seasonal patterns of abundance were synchronous in 1985 and 1986 for Egpodes spp. and Megs bedtgrfiiensis but not for others. For several taxa, significant relationships between abundance and soil moisture and temperature were established. Most importantly, turfgrass species exerted a significant influence on abundance and distribution of several taxa. Smooth bromegrass and Kentucky blues grass were generally favorable to figggxdagia spp. and Bhodagarellus silesiacue: highest abundance of the predaceous gypgagpig agglgifig; was recorded under tall fescue, while Megs W seemed to be numerous under redtop. Further studies of functional relationships between root system characteristics, associated microflora and arthropod population dynamics are recommended. 4 ./‘0‘ ”3'5?le —-':2 an. die name 0/04“ Lg; moat mull/Jane! Lg; mod gene/Lean! DEDICATION To my mother, for her love and support (May Allah forgive her and let her soul rest in peace) 11' ACKNOWLEDGMENTS The author wishes to express his sincere gratitude and appreciation to the members of his doctoral committee and especially to professor, Dr. Richard J. Snider, Chairman; for his valuable advice, guidance, encourage, and help during the course of this study. Grateful acknowledgment is also expressed to professor, Dr. Paul E. Rieke for his effort to provide the study area and a Valuable source for information about turfgrasses and soil. The author wishes to extend his sincere appreciation to Dr. IRenate Snider' for’ her’ assistance, encouragement and moral support: and to professor, Dr. Julius R. Hoffman for his assistance and for serving on my guidance committee. Special thanks to professor, Dr. John Gill for his assistance and help with statistical analyses of this study. My deep appreciation to my wife Hania for her unlimited patience, encouragement and understanding, and to mw' children Hanan and Amal, who sacrificed their precious moments of fatherly companionship. iii List List III. IV. TABLE OF CONTENTS of Tables . . . . . . . . . . . . . . . . . . . . VII of Figures . . . . . . . . . . . . . . . . . . . . IX INTRODUCTION . . . . . . . . . . . . . . . . . . . . 1 REVIEW OF LITERATURE . . . . . . . . . . . . . . . . 3 Horizontal patterns and effect of plant covers on population dynamics of arthropods . . . . . . . . . 3 Seasonal fluctuation and vertical distribution of soil arthropod population . . . . . . . . . . . . . 8 Effect of ecological factors on soil arthropod population dynamics . . . . . . . . . . . . . . . . 13 MATERIALS AND METHODS . . . . . . . . . . . . . . . 20 1. Site description . . . . . . . . . . . . . . . 20 2. Description of grassplant covers . . . . . . . 22 3. Soil analysis . . . .h. . . . . . . . . . . . 23 4. Soil temperature . . . . . . . . . . . . . . . 26 5. Soil moisture . . . . . . . . . . . . . . . . 26 6. Precipitation . . . . . . . . . . . . . . . . 27 7. Sampling and extraction methods . . . . . . . 27 8. Slides mounting technique . . . . . . . . . . 29 9. Statistical analysis . . . . . . . . . . . . . 30 RESULTS AND DISCUSSION . . . . . . . . . . . . . . 31 1. Ecological parameters . . . . . . . . . . . . 31 1.1 Soil Temperature . . . . . . . . . . . . . 31 iv 1.2 Soil Moisture . . . . . . . . . . . . 1.3 Precipitation . . . . . . . . . . . Distribution and dynamics of Acarina . . A. Existence Percentage of acarina order . B. Order Prostigmata . . . . . . . . . . . . . . . . 8.1 Effect of grass covers on population dynamics of Prostigmata . . . . . . . . . B.2 Biweekly fluctuation of prostigmatid mite populations . . . . . . . . . . . . . . . B.3 Vertical distribution of prostigmatid mite populations . . . . . . . . . . . . . . . C. Suborder: Heterostigmata . . . . . . . . . . . C.1 Genus Targgngmgg . . . . . . . . . . . . . C.2 Effect of grass covers on population dynamics of Taxggngmgg spp. . . . . . . . C.3 Biweekly fluctuation of Ta;§___mg§ spp. populations . . . . . . . . . . . . . C.4 Vertical distribution of Ia1__n§mg§ spp. populations . . . . . . . . . . . . . C.5 Genus flgkgzdania . . . . . . . . . . . . . C.6 Effect of grass covers on population dynamics of fiakgxgania spp. . . . . . . . C.7 Biweekly fluctuation of figkgggania spp. populations . . . . . . . . . . . . . C.8 Vertical distribution of Bakerggnig spp. populations . . . . . . . . . . . . . . . D. Suborder: Eupodina . . . . . . . . . . . . . . . D.1 D.2 Effect of grass covers on population dynamics of Eupgggg spp. . . . . . . . . Biweekly fluctuation of Enpgggs spp. populations . . . . . . . . . . . . . . . 38 38 4O 4O 40 43 43 46 55 55 55 58 58 65 65 68 68 78 78 78 D.3 Vertical distribution of Egpgggg spp. populations . . . . . . . . . . . . . . . . . 86 Family: Tydeidae . . . . . . . . . . . . . . . . . 9o E.1 Effect of grass covers on population ' dynamics of Iyggug bedfordiensis . . . . . . 90 E.2 Biweekly fluctuation of Tydeus bedfordignsis populations . . . . . . . . . . . 95 E.3 Vertical distribution of ngeu§ bgd£_rdi§n_i_ populations . . . . . . . 95 E.4 Effect of grass covers on population dynamics of Metanronematue leusghieneus . . . - - . - .102 3.5 Biweekly fluctuation of netapronematus leugghippgg_ populations . . . . . . .102 E.6 Vertical distribution of ugtangngmatug leugghippggs populations . . . . . .105 Order: Hesostigmata . . . . . . . . . . . . . . . .112 E.1 Effect of grass covers on population dynamics of Bhodasarellu§.sile§ia§u§ - - - - 112 F.2 Biweekly fluctuation of Bhodagarellug silegiaggg populations . . . . . . . . . . . .117 E.3 Vertical distribution of Bhodagazellus silesiagus populations . . . . . . . . . . . .117 F.4 Effect of grass covers on population dynamics of fiypgagpig aguleifgz. . . . . . . .122 F.5 Biweekly fluctuation of nypgaspis aguleifer populations . . . . . . . . 125 F.6 Vertical distribution of flypgaspis a_uleifer populations . . . . . . . . . . . 125 SUMMARY AND CONCLUSION . . . . . . . . . . . . . .135 BIBLIOGRAPHY O O O O O O O O O O O O O O O O O O O 14 0 vi VII 0 APPENDICES O O O O O O O O O O O O O O O O O O O O 14 5 APPENDIX A: Tables of sample means per grass and date C O O O O O O O O O O O O O O 1 4 6 APPENDIX B: Anova tables . . . . . . . . . . . . .163 APPENDIX C: Correlation and multiple regression analysis . . . . . . . . . . . . . . .172 vii 10. 11. 12. 13. 14. LIST OF TABLES List of turfgrass species in the study area . . . Average percentage of soil organic matter content under different grasses . . . . . . . . . . . . . Average recorded soil temperature (0C) and moisture during 1985 . . . . . . . . . . . . . . Average recorded soil temperature (0C) and moisture during 1986 . . . . . . . . . . . . . . Relative dominance of Acarina orders in 1985 and 1986 O O O O O O O O O O O O O O O O O O O O Population densities iSE/m2 of Prostigmata in each soil stratum under different grasses . . . . Mean seasonal density /m2 :SE of Prostigmata in upper and lower strata; data from all grasses lumped . Relative dominance of Heterostigmata genera in 1985 and 1986 O O O O O O O O O O O O O O O O O O Population densities iSE/m2 of Iazggngmgg spp. in each soil stratum under different grasses . . Mean seasonal density /m2 18E of Targgngmgg spp. in upper and lower strata: data from all grasses lumped O O O O O O O O O O O O O O O O O O O O O Population densities iSE/m2 of fiakgrgania spp. in each soil stratum under different grasses . . Mean seasonal density /m2 18E of nakgzgania spp. upper and lower strata: data from all grasses lumped O O O O O O O O O O O O O O O O O O O O O Relative dominance of Eupodina genera in 1985 and 1986 O O O O O O O O O O O O O O O O O O O O Population densities iSE/m2 of Egpgggg spp. in each soil stratum under different grasses . . viii Page 20 25 32 35 41 44 47 .56 59 61 69 71 79 81 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. Mean seasonal density /m2 18E of Eupgggfi spp. in upper and lower strata: data from all grasses lumped O O O O O O O O O O O O O O O O O O O O O O O 8 3 Relative dominance of species in the family Tydeidae in 1985 and 1986 O O O O O O O O O O O O O O O O O O 91 Population densities iSE/m2 of Tygggg bedfordignsis in each soil stratum under different grasses . . . . 93 Mean seasonal density /m2 18E of Tygggs bedfordiensis in upper and lower strata: data from all grasses lumped O O O O O O O O O O O O O O O O O O O O O O O 9 6 Population densities :SE/m2 of Metaprgngmatus leugghippeus in each soil stratum under different grasses O O O O O O O O O O O O O O O O O O O O O O 103 Mean seasonal density /m2 38E of m leugghippeus in upper and lower strata: data from all grasses lumped . . . . . . . . . . . . . . . . .106 Relative dominance of species of order Mesostigmata in 1985 and 1986 O O O O O O O O O O O O O O O O O O 113 Population densities iSE/n2 of Rhodagarellus silesiagus in each soil stratum under different grasses . . . .115 Mean seasonal density /m2 18E of Rhggagarellug fiilgsiagug in upper and lower strata: data from all grasses lumped . . . . . . . . . . . . . . . . .118 Population densities iSE/m2 cf nypgagpis agnleifg; in each soil stratum under different grasses . . . .126 Mean seasonal density /m2 iSE of fiypgaspifi aguleife: in upper and lower strata; data from all grasses lumped O O O O O O O O O O O O O O O O O O O O O O O 128 APPENDIX A: Tables of sample means per grass and date . .146 APPENDIX B: Anova tables . . . . . . . . . . . . . . . . 163 APPENDIX C: Correlation and multiple regression analysis . . . . . . . . . . . . . . . . . . 172 ix 10. 11. 12. 13. 14. 15. LIST OF FIGURES Page Diagram of the 6 sample blocks and their different grass covers . . . . . . . . . . . . . . . 21 Diagram of soil core device . . . . . . . . . . . . .28 Average recorded soil temperature and moisture of the 0 - 15 cm stratum during 1985 . . . . . . . . . 33 Average recorded soil temperature and moisture of the 16 - 30 cm stratum during 1985 . . . . . . . . . 34 Average recorded soil temperature and moisture of the 0 - 15 cm stratum during 1986 . . . . . . . . . .36 Average recorded soil temperature and moisture of the 16 - 30 cm stratum during 1986 . . . . . . . . . 37 Amount of precipitation received in the study area during 1985 and 1986 . . . . . . . . . . . . . 39 Relative dominance (t) of acarine orders (all grasses lumped) . . . . . . . . . . . . . . . . . . 42 Prostigmata densities /m2 in both soil strata under different grass covers . . . . . . . . . . . . . . 45 Biweekly fluctuation of Prostigmata during 1985, all grasses combined . . . . . . . . . . . . . . . 48 Biweekly fluctuation of Prostigmata during 1986, all grasses combined . . . . . . . . . . . . . . . 49 Vertical distribution of Prostigmata during 1985 and 1986, all grasses combined . . . . . . . . . . 51 Mean seasonal densities of order Prostigmata under different grasses at each depth during 1985 . . . . 53 Mean seasonal densities of order Prostigmata under different grasses at each depth during 1986 . . . . 54 Relative dominance (%) of heterostigmatid genera in 1985 and 1986 O O O O O O O O O O O O O O O O O O 57 X 16. Taxggngmgg spp. densities /m2 in both soil strata under different grass covers . . . . . . . . . . . 60 17. Biweekly fluctuation of Ia;_gngmg§ spp. during 1985, all grasses combined . . . . . . . . . . . . . 62 18. Biweekly fluctuation of Iazggngmns spp. during 1986, all grasses combined . . . . . . . . . . . . . 63 19. Vertical distribution of Targgngmug spp. during 1985 and 1986, all grasses combined . . . . . . . . . . .64 20. Mean seasonal densities of Tagsgngmgg spp. under different grasses at each depth during 1985 . . . . 66 21. Mean seasonal densities of Iazggngmgg spp. under different grasses at each depth during 1986 . . . . 67 22. figkgzganig spp. densities /m2 in both soil strata under different grass covers . . . . . . . . . . . 70 23. Biweekly fluctuation of Bakgxgania spp. during 1985, all grasses combined . . . . . . . . . . . . . . 72 24. Biweekly fluctuation of figkgzggnia spp. during 1986, all grasses combined . . . . . . . . . . . . . . . 73 25. Vertical distribution of Bakgzggnia spp. during 1985. and 1986, all grasses combined . . . . . . . . . . .74 26. Mean seasonal densities of Bakgngania spp. under different grasses at each depth during 1985 . . . . 76 27. Mean seasonal densities of Bakezdania spp. under different grasses at each depth during 1986 . . . . .77 28. Relative dominance (%) of Eupodina genera in 1985 and 1986 O O O O O O O O O O O O O O O O O O O O O 80 29. Egpgges spp. densities /m2 in both soil strata under different grass covers . . . . . . . . . . . . . . 82 30. Biweekly fluctuation of Eupgggg spp. during 1985, all grasses combined . . . . . . . . . . . . . . . 84 31. Biweekly fluctuation of Enpgggg spp. during 1986, all grasses combined . . . . . . . . . . . . . . . 85 32. Vertical distribution of Eupgggg spp. during 1985. and 1986, all grasses combined . . . . . . . . . . . . 87 xi 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. Mean seasonal densities of Eupodgg spp. under different grasses at each depth during 1985 . . . . 88 Mean seasonal densities of Egpgggg spp. under different grasses at each depth during 1986 . . . . 89 Relative dominance (%) of selected species of Tydeidae in 1985 and 1986 O O O O O O O O O O O O O O O O O 92 Tydgus bedfordiensis densities /m2 in both soil strata under different grass covers . . . . . . . . 94 Biweekly fluctuation of Tygggg bggfigzdiengis during 1985, all grasses combined . . . . . . .97 Biweekly fluctuation of Iygggfi hggfigzgigngig during 1986, all grasses combined . . . . . . . .98 Vertical distribution of Tygggfi begfigzgigngig during 1985 and 1986, all grasses combined . . . . . . 99 Mean seasonal densities of Iygggg bggfgzgiengis under different grasses at each depth during 1985 . . . .100 Mean seasonal densities of Iygegfi bggfgrgigngig under different grasses at each depth during 1986 . . . .101 leggghippgng densities /m2 in both soil strata under different grass covers . . . . . . . .104 Biweekly fluctuation of Meteoronematus leusohinneus during 1985, all grasses combined . . . . . .107 Biweekly fluctuation of Metanronematus leucohinneus during 1986, all grasses combined . . . . . .108 Vertical distribution of Meteoronematus leusohineeus during 1985 and 1986, all grasses combined . . . . 109 Mean seasonal densities of Motocronematus leucohieeeus under different grasses at each depth during 1985 . 110 Mean seasonal densities of Motocronematus leucohipeeus under different grasses at each depth during 1986 . 111 Relative dominance (%) of selected species of Mesostigmata in 1985 and 1986 . . . . . . . . . . .114 silesiaggg densities /m2 in both soil strata under different grass covers . . . . . . . .116 xii 50. 51. 52. 53. 54. 55. 56. 57. 58. 59. 60. Biweekly fluctuation of Bhodasarellus silesiasus during 1985, all grasses combined . . . . . .119 Biweekly fluctuation of Bhodagarelluslsilesiagus during 1986, all grasses combined . . . . . .120 Vertical distribution of Rhodagarellus silesiacus during 1985 and 1986, all grasses combined . . . . 121 Mean seasonal densities of Bhodagazgllug gilggiagug under different grasses at each depth during 1985 . 123 Mean seasonal densities of Bhodagazellug gilgsiagug under different grasses at each depth during 1986 . 124 aguleifg: densities /m2 in both soil strata under different grass covers . . . . . . . . . . . 127 Biweekly fluctuation of fiypgaspis aggleifig: during 1985, all grasses combined . . . . . 129 Biweekly fluctuation of fiypgaspig aggleifg; during 1986, all grasses combined . . . . . . 130 Vertical distribution of fiypggfinig agnleifg; during 1985 and 1986, all grasses combined . . . . . .131 Mean seasonal densities of fiypgaspig agglgifig; under different grasses at each depth during 1985 . . . . 133 Mean seasonal densities of flypgggpifi agglgifig; under different grasses at each depth during 1986 . . . . 134 xiii I . INTRODUCTION The edaphic ecosystem is profoundly marked by a great number of dependent interrelations. we are constantly confronted with many functional relationships that mites share with other organisms. Therefore, the study of soil mites must fundamentally be an ecological one. Soil mites have wide spatial and temporal distributions, great species diversity, and narrow ecological sensitivity making them a prime candidate for ecological studies. Turfgrass is a complex system consisting of roots, stems, and leaves of grass plants together with a tightly intermingled. layer' of'ldead and. living roots, stems and organic debris commonly called thatch. This habitat supports a diverse assemblage of invertebrates (Streu, 1973: Cockfield. and Potter 1983). ' Taxa that are present in turfgrass include Annelida, Nematoda, Diplopoda, Protura, Acarina and Collembola: they are considered important to plant-litter decomposition and nutrient recycling in soil communities. These animals aid the decomposition process by fragmenting and conditioning plant debris in their guts before further breakdown by microflora (Lofty, 1974: Wallwork, 1983). They are also responsible for disseminating 1 bacteria and fungi, enriching the soil and mixing organic materials into the soil while migrating vertically. Distribution and abundance of soil animals are determined by a large number of factors, among the abiotic factors, soil moisture, temperature, pH and organic matter are highly important (Hagvar and Abrahamsen, 1980). From a survey of literature, it was found that little has been done in studying population dynamics of soil organisms inhabiting turfgrass systems. Therefore this study was undertaken to answer the following questions: 1. What is the effect of different grass covers on the abundance of the most dominant prostigmatid and mesostigmatid mite species and genera? 2. What are the seasonal dynamics of selected mite species and genera in relation to major ecological factors? 3. What is the vertical distribution of selected mite species and genera in relation to major ecological factors? II. REVIEW OF LITERATURE 1. o tt 5 la t covers on The importance of habitat has been emphasized by Southwood (1977). It remains as a basic step in the concrete study of any ecosystem. However, ecosystem descriptions, as with any system, depends on the selected space-time resolution level. Dillon and Gibson (1962) reported that the Isotomidae (Collembola) and Eupodidae (Acarina) were overwhelmingly dominant families in an old meadow. They found that an unusual feature was the virtual absence of Oribatei, which was possibly related to soil dryness. They also stated that populations of both Collembola and Acarina fluctuated with time and showed no regular seasonal rhythm and the vertical movements of almost all species occurred from time to time with no seasonal regularity: there was no evidence that the changes as a whole bore any simple relationship to fluctuation of soil temperature, moisture, pH or organic content. They also reported that among mesostigmatid mites, Rhodacaridae were exceptional in being most numerous. Christiansen, in the case of Collembola, (1964) summed up the connection with macroflora by saying that there is generally a moderate amount of correspondence between plant cover and collembolan association, but little evidence of restriction of individual Collembola species to one species of plant. Christen (1974) ‘ stated that it is general knowledge that numbers of soil microarthropods vary under different types of plant cover. Pasture crops with dense root systems generally can be expected to support larger populations than cultivated row crops, thus reflecting root influence. Alejnikova and Utrobina (1975) said that the variety of soil invertebrate species increase in the same way as their density reaching a maximum under perennial grass and in field plantations. They also pointed out that plant cover effects were most striking in the case of microarthropods, in particular when they compared population density and group composition in four crop rotations. Depending on plant cover, dominance of individual species also changed. The authors suggested that, since plant cover greatly affected soil animal population structure, man could control soil animals and ultimately soil fertility by changing farm crop composition. Krivolutsky (1975) reported that oribatid mite population density was highest in forest soils and lowest in desert. soils. His studies suggested. that oribatid. mites could be used as a soil type bioindicator. Singh and Pillai (1975) studied microarthropod population density in a wide variety of habitats and found that Acari were the most dominant group in all habitats, ranging from 45.5 to 71.7% of the total fauna, while Collembola ranged from 11.9 to 41.7%. They also noticed that Collembola and Oribatei were dominant in higher organic matter soils, while Prostigmata predominated in soils, poor in organic matter. Loring et al. (1981) stated that no-till plots had stable populations of Collembola and. Acarina ‘which fluctuated regularly. Plowed plots exhibited a sharp decrease in populations, followed by a sharp increase in populations, followed by a sharp increase in populations toward the end of the growing season. Petersen (1982) stated that great diffrences have been found between population fluctuations of individual acarine orders. Thus, data compiled for Prostigmata and Astigmata provided a number of examples of density changes, one month with several thousands/m2 and virtual absence of members of these taxa in another month. Contrary to this, Cryptostigmata and Mesostigmata generally showed moderate changes in population size. For collembola and Acari, woodland sites showed weaker annual amplitudes in population density than non-wooded sites. By comparing tropical and temperate regions, he was able to say that in most cases grassland sites in tropical regions showed higher fluctuatios than temperate grassland sites. Observed differences between communities were explained mainly as diffrences in environmental stability under, the infuence of local climate, soil properties and degree of exposure. Whelan (1985) sampled. the herbs and soil of three grassland sites each month for one year. The soil also was sampled to a depth of 7.6 cm, then divided into two subsamples of 3.8 cm each. Peak populations of Acari were recorded in the summer months which corresponded with high herb populations. Permanent pasture had high populations in the soil especially in the 3.8 - 7.6 cm stratum. Whelan (1986) then reported that populations in herbaceous stratum, were dominated by microphytophagous and panphytophagous species while microphytophagous and predacious species dominated the soil populations. Hendrix et al. (1986) suggested that the decomposition processes of no-tillage agroecosystems were functionally similar to those occurring in natural systems, where gradual decay of organic matter and slow nutrient release from plant residues is under the control of soil fauna as well as microflora. Curry and Mbmen (1988) studied the arthropod fauna of managed grassland 2.5 and 6 years old; unmanaged 6 years old grassland: and an old field margin on reclaimed cutaway peat. They recorded 209 species or higher taxa including 5 new species. Mean collembolan population densities reached a maximum in the 2.5 year site, while a minimum was recorded in the old field margin. Meesostigmata dominated all habitats except the 2.5 years-old site where Astigmata were most abundant. Sheals (1957) suggested that seasonal fluctuations of soil Cryptostigmata in uncultivated grassland where caused by movement to other habitats for reproduction. Hayes (1963), Wood (1967) and Imxton (1972) suggested that depth distribution of mite species may be controlled by a complex of physiological and behavioral characteristics. Importance of food selection and influence of relative humidity and temperature also appeared to be considerable. Hayes (1965) stated that all species of phthiracarid mites occurred predominantly in litter and humus with no real seasonal differences. Madge (1965) reported the highest number of oribatid mites during winter (November-February) and the lowest during late summer and fall (July-October) at Rothamsted Experimental Station. Fujikawa (1970) recorded the average population density (individual no. /20cm2) of the upper 15 cm of soil over 15 sampling occasions was 13.8:6.9 in a natural Picea forest. The most complex faunal composition was observed in the natural mixed ferest. In most cases the population density in the upper 5.0 cm layer of soil was significantly greater than that in the 5-10 cm and 10-15 cm strata. Anderson (1971) suggested that vertical distribution of Oribatei was governed more by selection of certain food materials and characteristics of soil horizons than by physical characteristics of their environment. Usher (1971) mentioned that of 22 mesostigmatid species studied, seasonal distribution Was detected in 15 species. Only 5 of these showed single annual maximum population densities. The mesostigmatids Egrgamaggg lappgniggg and Egigaia transigalag were autumn species, since their maximum population size was recorded during September, October and November. W sp. was a winter species with maximum population during January and February. Argtgseigg man: and W m were summer species. He also observed that, among mesostigmatid populations, there was no intense vertical stratification during periods of suitable climatic conditions. However, when climatic factors became less suitable: the animals migrated, downwards, establishing a more defined vertical stratification. Wallwork (1972), in his study of distribution patterns and population dynamics of microarthropods in juniper litter and underlying mineral soil, pointed out that peak densities 10 occurred in April and December. The December peak was produced mainly by population increases in mineral soil, whereas the April peak reflected population increases in litter. Price (1973) reported prostigmatid adaptations to xeric conditions, and cautioned against shallow sampling which can result in substantial underestimates of total soil microarthropod populations. Fujikawa (1974) compared oribatid faunas from different microhabitats in a forest floor. He found that each stratum contained a particular fauna, and the number of individuals as well as species of oribatid mites in litter stratum was comparable to that observed in soil strata. Pande and Berthet (1975) found no statistically significant correlation between species size and their depth penetration, although it remains generally true that larger species dominate the surface layers of soil (Stepanich 1975). Aitchison (1979) investigated snow cover effects in southern Manitoba, and found that the families Eupodidae, Rhagidiidae and Parasitidae were some of the most abundant winter-active groups. She also found no correlation between number of trapped mites and below-snow temperature. 11 Zacharda (1979a.) stated that some rhagidiids were polyvoltine and.that the occurrence of their developmental stages was season-independent. On the other hand some species were monovoltine with strictly season-dependent life cycles: adults of species inhabiting dry habitats, e.g., xerotherm grassy steppes and rocky dry steppes, occured predominantly in winter and disappeared during spring and summer . Holt (1981) suggested that vertical distribution of adult Cryptostigmata was highly correlated with percent organic matter, and distribution of larger individuals appeared not to be influenced by pore size or total soil porosity. Distribution of numerous smaller Cryptostigmata appeared to be influenced by availability of smaller soil pores. Salem ( 1981) recorded monthly fluctuations in population densities of tarsonemid mite species in relation to soil temperature and moisture in Egypt. He reported that the highest population densities of Acarina groups occurred in spring and fall. Darlong and Alfred. (1982) found a general trend for mean total populations of soil arthropods to increase in 12 both forest and Jhum sites with the advent of the warm and rainy season. This decreased with the advent of the dry and cold season. He also saw seasonal variations among different soil arthropod groups which may have been due to vertical movements. Leetham and Milchunas (1985) suggested that composition and distribution of soil microarthropods on the semiarid shortgrass steppe was a function of tradeoffs between resource availability and environmental benignity mediated through body size constraints on the ability to withstand cycles of anhydrobiosis. 13 3. 7‘ = O ‘ e 0‘ -. o. o : or ‘9, -. 0.0-! According to Andrewartha and Birch (1954) population size is determined by four components of the environment: weather, food, other animals and pathogens, and locus. Individual importance of these components may vary between different populations in different habitats. For terrestrial animals, variation of specific physical conditions (climate) greatly influences all parameters of population growth. The combination of soil moisture and temperature is' the most important factor for soil animals. Many studies have demonstrated that soil arthropods are non- randomly distributed. The following is a review of the factors causing this non-randomness. Loots and Ryke (1967) obtained a highly significant correlation value of 0.90 between the ratio of Oribatei: Trombidiformes and the percentage of organic matter in different soils. Oribatei dominated in soils with high organic matter, whereas Trombidiformes were more abundant in soils with low percentage of organic materials. They suggested that small species of trombidiforms might feed on protozoa and bacteria which are present in small pore spaces. 14 Bursell (1970) found that moisture deficiency could be an important mortality factor. Mukharji and Singh ( 1970) stated that there was a direct correlation between soil moisture content, temperature and arthropod population dynamics. They concluded that as soil moisture increased, arthropod. populations simultaneously increased and vice- versa . Butcher et al. (1971) summarized that the majority of Collembola and Cryptostigmata studies reviewed, reported an aggregated distribution of individuals within the three dimensional environment of the soil. They concluded that aggregation tendencies could be attributed to "water, temperature, time of day, microclimate, season, food source, microflora, vegetation, etc....." and that the reliability of estimating each of these influences depended in part upon the extent to which individual investigator, sought to document their speculations, inferences or conclusions. Chernova et al. (1971) in Russia found that both numbers and biomass of micro-arthropods increased with a rise in organic matter content. Edwards and Lofty (1971) in England reported that some soil-inhabiting invertebrates survived extreme heat or cold in an active phase. But this was unusual, more often they became inactive and aestivated, coincident with adverse periods, or survived as eggs or 15 pupae. Some species avoided extreme temperatures at the soil surface by moving down into soil strata where temperatures were less extreme and much more stable until the surface again became acceptable. The same authors also commented that changes in temperature can influence numbers of soil-inhabiting invertebrates not only directly, but also indirectly by changing the moisture content of soil. Most dry soils have a specific heat of only about 0.2 cal./g so that they warm up rapidly when exposed to the sun. Increasing their moisture content increased thermal capacity, and warming up took place less rapidly. Wet soils also had a greater thermal conductivity than dry soils so that temperature gradients in them were less than those in dry soils. All these factors may influence the effects of extreme temperature on invertebrates in soils. Metz (1971) reported that substrate moisture content determines, to a large degree, number of micro-arthropods. On several occasions, his litter samples from Loblolly pine forest floors after several weeks of drought yielded very 16 few mites: 2 days after wetting a square meter of the floor with 20 liters of water, from 5 to 10 times more mites were recovered. The same author described a laboratory experiment to determine survival and movement of mites under different moisture regimes. Groups of mites, including seven species of Oribatei, were shown to move between mineral soil and organic layers as moisture conditions changed. Mesostigmata had a better survival rate than either Oribatei or Trombidiformes. Usher (1975) demonstrated a relationship between numbers of arthropods and soil moisture or soil temperature, while Plowman (1979) was unable to find any such relationships. The former author (1976) indicated that patchy distribution of either food or soil water was the most likely cause of soil arthropod aggregations. Wallwork (1976) suggested that correlation between environmental factors and species assemblages were of limited value because a complexity of environmental factors acted upon the species and because of different physiological tolerances of different species. 17 Mitchell (1979) pointed out that a forest soil was a mosaic of biotic and abiotic components, arranged differentially with respect to horizontal and vertical distribution and 'temporal patterns. Of’ the abiotic parameters, temperature and moisture seemed especially critical in affecting physiological activity and distribution of oribatids. Depth was a complex variable linked with a number of components, all of which may affect both inter-and intra- specific oribatid distribution. Food was probably the most important factor affecting the biology of oribatids. The distribution and population dynamics of microphytophages may be directly related to availability of microbial food resources. Regniere (1980) said. that soil insects ‘were highly dependent on soil moisture which had direct effects on egg development and hatching. Joosse (1981) stated that population changes of some collembolan species were infuenced by an interacting complex of biotic and physical factors, which varied according to environmental favourability. Luxton (1981) concluded that environmental variables such as precipitation and litter fall may exert important short-term infuences on some populations, and that the same 18 species in different environments may not always be confidently compared to a single phenological pattern. Whitford et al. (1981) have shown that in desert ecosystems, mites, Collembola and nematodes all reacted, very quickly to simulated rainfall, increasing significantly in litter within an hour after it was moistened. Petersen (1982) reported a high proportion of prostigmata and a relatively low ratio of Collembola to total Acarina in shortgrass steppe. He attributed this to a negative correlation between acarine density and soil moisture, and a positive correlation between collembolan density, soil moisture and organic matter. Boyne and Rain (1983) studied the development and fecundity of Nggggiulgg .fallagig under various relative humidity levels and found them similar for all relative humidity ranges tested, except at the lowest range (60-65%). There none of the individuals survived to maturity. Mitra et al. (1983) stated that in grassy plots, higher temperature and Run. resulted in an increase in number of Collembola, while lower temperature and R.H. were preferred by Acarina. Hagvar (1984) studied "6 common mite species in Norwegian coniferous forest soils." He found that the 19 abundance of these species in different soils was related to a number of soil chemical factors. Their occurrence was also related to soil and humus types, plant communities and soil fertility. III. MATERIALS AND METHODS 1. ' es ' t' n: This study was conducted at the Hancock Turfgrass Research Center, located on the campus of Michigan State University. To study the effects of turfgrass types on the bionomics of soil acarina, 6 grasses were seeded into plots during 1982, and are listed in Table 1. Table 1: List of turfgrass species in the study area Common Name Scientific Name Smooth bromegrass Bromus inermis Kentucky bluegrass .293 protengis Orchardgrass Qagtylis glgmezata Timothy mm matches Tall fescue Egstuga armadinageae Redtop Agrgstis alba The turf blocks measured 8.2 m by 9.1 m with the long axis running north to south (Figure 1). All blocks were mowed at a height of 10.2 cm on 8 May, 1983 and 10 May 1984 20 21 osomou name mmoumcuenouo asuoaaa -neumosnn axosuso. sample blocks and their different Diagram of the 6 grass covers. Figure 1. 22 and were then kept without any treatment until sampling began in 1985. 2. Bescrietion_2f_grassplant_soxers A. Smooth bromegrass (firgmgg ingzmis) Forms an upright, coarse textured turf which spreads vegetatively by vigorous, fleshy rhizomes that fomm a firm sod. Root system extensive. B Kentucky bluegrass (29a protengig) Forms a medium textured, green to dark turf of good shoot. density. The extensive root system in concentrated primarily in the upper 15-25 cm of the soil profile, some roots may penetrate to depths of 40 to 60 cm under mowed conditions. Root system persists as a perennial. C- Orchardgrass (Bactylis.glomerata) The texture of this grass is quite coarse with leaves folded in the bud shoot and sheaths distinctly compressed. It forms an open sod of low shoot density. Orchardgrass is basically a bunch-type grass since it has neither rhizomes nor stolons. Orchardgrass has rapid early spring growth, its drought tolerance is greater than that of timothy but not as good as that of smooth bromegrass. 23 0. Timothy (Ehleum snatches) This grass tend to behave as a bunch type with poor sod forming qualities. Leaves frequently have a grayish-green appearance. The root system is shallow, fibrous and replaced annually. E. Tall fescue (fiestas; arundinaseae) Forms a turf of very low shoot density and has dark green leaves. The root system. is extensive, coarse and deeper than most cool season turf grass. r. Redtop (Agnostic alba) Forms a stemmy, coarse textured, open turf of low shoot density. The root system is regenerated annually. 3. Soil_Analysis: After Tullgren extraction of arthropods, the first 36 soil samples obtained from the study site were composited, passed through a 2-mm sieve and subsampled. Soil pH, K, Ca, Mg, and P were determined according to routine methods of the Soil Testing Laboratory of Michigan State University. Soil pH was determined in 1:1 water suspension, using a Beckman zeromatic glass electrode pH meter. Phosphorus was extracted with Bray p-1 reagent using a 1:8 soil to solution 24 ratio: available K, Ca, and Hg with 1-0 N NH4 OAC (pH 7.0) using 1:8 soil to solution ratio. The study area's soil type is fine loamy, mixed, Mesic Aeric Ochraquairs (formerly Capac Sandy Clay Loam). The soil texture is classified as sandy clay loam, with pH of 7.3. Soil chemical test results for available nutrients were as follows: available P = 173 lb/A exchangeable K = 280 lb/A available Ca 4480 lb/A available Mg 547 lb/A Soil organic matter contents also were determined according to routine methods of the Soil Testing Laboratory of Michigan State University as follows: Reagents: 1. 0.5 M NaZCrZO7: Dissolve 149 g of NaZCr207 2 H20 in water and dilute to 1 liter. 2. H2504, concentrated, 96%. Procedure: 1. Using an NCR-13 1-g scoop, scoop 1 g of soil into a 50-mL Erlenmeyer flask, using standard scooping techniques. 2. Add 10 mL of NaZCr207 solution by means of dispenser. 3. Add 10 mL of concentrated sulfuric acid, using a suitable dispenser. A supply of 2% NaHCO3 should be readily 5. 6. 25 available to nutralize spilled acid on skin, clothing, or lab bench. Allow to react for 30 minutes. Dilute with 15 mL of water and mix. Allow to stand three hours or overnight. Transfer 10 mL (or other suitable volume) of clear supernatant into a colorimeter tube. This can be accomplished conviniently by use of a pipette bank set to dip a suitable distance into the supernatant solution. Care must be taken not to disturb the sediment on the bottom of the flask. The blue color intensity of the supernatant is read on a colorimeter at 645 nm, with the reagent blank set to give 100% transmittance (or 0 absorbance). The instrument is calibrated to read percent organic matter (or tons per acre) from a standard curve prepared from soils of known organic matter content. Soil organic matter averaged between 3.2% and 3.7% (Table 2), indicating good uniformity among turf blocks. 26 Table 2: Average percent of soil organic matter under different grasses. Grasses % of Organic matter % of organic matter 0-15 cm stratum 15-30 cm stratum Smooth bromegrass 3.4 3.2 Kentucky bluegrass 3.2 3.3 Orchardgrass 3.6 3.7 Timothy 3.6 3.7 Tall fescue 3.3 3.5 Redtop 3.6 3.6 4. W: A Yellow Springs telethermometer with a 12 cm probe was used to record soil temperature after allowing it to equilibrate in the soil for at least 1/2 hour. Temperature was measured at two depths: 7.5 cm and 23.5 cm on each sampling date under each grass. 5. W: On each biweekly sampling date, 1 sample from each depth layer under each grass was placed in tightly covered containers, 6.5 cm high by 9 cm diameter: samples were weighed wet, oven-dried at 60°C oven for one week or until 27 no further weight loss occurred, and re-weighed. Percent soil moisture was obtained by using the following equation: % soil moisture 100[(wet weight-dry weight)/ dry weight]. 6. 23212113111211: Precipitation data were obtained from the U. S. National Weather Service, South Farm Station, which is very close to the study area. 7. Sa pling and extraction methods: Three replicate samples per date, cut in half to provide subsamples of the upper and lower profile (0 - 15 and 16 - 30 cm) were taken from each turf block using a metal coring device with a diameter of 6 cm and a height of 15 cm with a tapered interior edge to relieve compression of the core (Figure 2). Thirty-six samples were thus taken on a biweekly schedule from April 15 to December 1, 1985 and from April 1 until December 1, 1986. Samples were sealed in plastic bags and were transported in an ice chest to prevent temperature-induced mortality before extraction. Extraction was initiated less than one hour after collection by using Tullgren funnels. To provide heat, each funnel had a 25-watt light bulb connected to a rheostat. A labelled vial with a solution of 1% glycerin in 95% ethanol was placed beneath each funnel. Soil cores were extracted 28 : 40.56!!! . -. _ Q 1 20cm J—H it 22:03 *S'cmr' it Figure 2. Diagram of soil core device. 29 for 72 hours, heat intensity being gradually increased to maximum during this time. Collected animals were initially separated into collembolan families, mite orders, spiders, centipedes, millipedes and other arthropods. Two orders of mites, Mesostigmata and Prostigmata, were separated and mounted on slides for further identification to genus and species levels. 8. W: All specimens of the orders Mesostigmata and Prostigmata were mounted for further identification as follows: 1. Clearing in a solution of 10% KOH for 10 minutes. 2. Washing in distilled water for 5 minutes. 3. Mounting in a drop of Hoyer’s media on a glass slide, straightening the specimens’ appendages, then covering them with coverslips of size 00. 4. Heating in a 50°C oven overnight, then ringing the covers with nail polish for a permanent seal. The collections were deposited at the laboratory of Invertebrate Zoology, Michigan State University. 3o 9. Wis: Split-plot analysis of variance was used to test the effects of the three main factors included in this study: grass type, biweekly sampling dates (season) and profile depth, along with their interactions. Tukey’s Test was used for comparison among means whenever significant differences occurred. Correlation analysis and multiple regression were used to study relationships among population density, % soil moisture and soil temperature. ANOVA tables of split-plot and multiple regression analysis, and results of simple correlations, are given in appendices. IV. RESULTS AND DISCUSSION 1. W 1.1. W Since temperature did not differ significantly with grass type, the data presented in Tables 3 and 4 are averages for each depth and date of 1985 and 1986. However, soil temperatures were significantly different among sampling dates ( two-way analysis of variance ). In 1985, the highest temperatures were recorded on July 1, July 15 and Aug 1, at approximately 27°C for the 0 - 15 cm stratum (Figure 3), and at slightly over 25°C for the 16 - 30 cm stratum. Soil temperature started to decrease beginning October 1, 1985, with only 1°C being recorded on December 1 (Figure 4). In 1986, the highest recorded soil temperature occurred on July 15, with an average of approximately 28°C in the upper soil stratum, while it was slightly over 25°C in the 16 - 30 cm stratum. Temperature began decreasing in early October until it dropped to less than 1°C in November and December (Figures 5 and 6). 31 32 Table 3: Average recorded soil temperature ('C) and moisture during 1985. ==-Li 0 - 15 cm #74:; 16 - 30 cm Moisture Temp 'C Moisture Temp 'C Dates Mean SD Mean SD Mean SD Mean SD Aprl 1 --- --- --- --- --- --- --- --- Aprl 15 15.9 $1.7 12.0 $0.5 17.7 $1.0 8.5 $0.4 May 1 16.0 $1.7 12.9 $0.4 13.3 $1.1 11.8 $0.4 May 15 13.8 $1.6 16.3 $0.8 11.3 $1.0 13.6 $0.5 June 1 10.6 $1.2 16.7 $0.6 9.6 $1.3 14.0 $0.5 June 15 13.8 $1.8 17.3 $0.4 10.8 $1.0 15.7 $0.5 July 1 6.4 $1.1 26.3 $0.5 8.0 $1.1 22.9 $0.3 July 15 11.2 $1.4 26.5 $0.3 7.0 $1.4 25.3 $0.3 Aug 1 6.5 $1.1 26.3 $0.4 5.4 $1.0 23.6 $0.3 Aug 15 11.2 $1.1 21.6 $0.4 9.8 $1.2 18.3 $0.2 Sept 1 14.2 $1.4 25.4 $0.3 13.7 $1.4 21.7 $0.6 Sept 15 10.2 $0.9 19.5 $0.5 10.7 $1.4 17.9 $0.3 Oct 1 15.1 $0.7 11.2 $0.3 12.9 $0.8 10.1. $0.1 Oct 15 12.8 11.0 12.2 10.2 12.2 20.9 11.1' 10.1 NOV 1 16.6 $0.4 11.3 $0.3 15.6 $1.1 10.1 $0.2 NOV 15 16.2 $1.3 12.1 $0.3 14.4 $1.1 10.2 $0.2 Dec 1 16.9 $3.1 0.9 $0.1 14.8 $2.4 2.2 $0.1 Each mean derived from 6 measurements/date. 33 °/o Moisture and Temperature C 1st depth 1985 Moisture % Temperature C 20 30 ............ '1 ................. / \¥/\ - /\/ \ 11/ A\ /\/ .............. -20 10 J VAV \A/t . I ' \ '10 5 ..... ............................................................ ....5 0 I I I I I F F T I I I I I r I PO A A M M J .1 J J A A S S 0 O N N D 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 5 5 5 5 5 5 5 5 date —— 96 Moisture —+— Temperature C Figure 3. Average recorded soil temperature and moisture of the 0 - 15 cm stratum during 1985. 34 °/o Moisture and Temperature C 2nd depth 1985 Moisture % Temperature C 18 30 —— % Moisture —*— Temperature C Figure 4. Average recorded soil temperature and moisture of the 16 - 30 cm stratum during 1985. Table 4: Average recorded soil temperature (°C) and moisture during 1986. 0 - 15 cm 16 - 30 cm Moisture Temp 'C Moisture Temp 'C Dates Mean SE Mean SE Mean SE Mean SE m =— I Aprl 1 15.9 $1.4 11.7 $0.2 14.8 $0.9 8.2 $0.2 Aprl 15 15.7 $1.4 13.4 $0.2 13.7 $1.4 12.4 $0.5 May 1 12.7 $1.6 11.5 $0.5 11.3 $1.4 9.6 $0.5 May 15 16.7 $1.9 19.8 $0.3 14.5 $1.6 17.3 $0.3 June 1 9.2 $1.6 20.4 $0.2 11.5 $1.5 18.4 $0.3 June 15 14.2 $1.3 20.6 $0.3 14.1 $0.8 19.4 $0.1 July 1 12.7 $1.0 19.6 $0.2 14.3 $0.7 18.6 $0.1 July 15 13.4 $1.0 27.6 $0.3 14.5 $0.3 25.3 $0.3 Aug 1 13.4 $2.0 22.7 $0.3 11.7 $1.7 21.2 $0.2 Aug 15 12.6 $1.8 23.3 $0.4 11.0 $1.5 22.0 $0.3 'Sept 1 15.9' 12.2 18.6 10.1 13.7 :1.7 17.5 30.1 Sept 15 16.9 $1.8 17.1 $0.4 15.3 $1.0 15.5 $0.1 Oct 1 21.0 $2.5 13.5 $0.8 17.8 $1.2 14.0 $0.6 Oct 15 16.5 $0.8 10.1 $0.4 15.2 $1.0 9.1 $0.2 Nov 1 19.4 $1.1 9.0 $0.8 15.4 $0.5 9.0 $0.3 NOV 15 15.4 $1.1 1.0 $0.2 14.1 $0.7 1.6 $0.3 Dec 1 17.5 $2.1 1.4 $0.2 16.1 $1.7 2.3 $0.2 36 % Moisture and Temperature C 131 depth 1986 Moisture 16 Temperature C 25 30 /\ 22 20 /[ \\/\ / \ ......... ._44—‘4\\\F , L120 ,2 fivfl >( //\\/W \\ 101/‘\\(_ V -10 5“ 1.5 0 I I I I I i I I T I I 0 A A M M J J J'J A A S S D 1 1 1 1 1 1 1 1 1 1 1 1 1 5 5 5 5 5 5 depth — 16 Moisture —+— Temperature C Figure 5. Average recorded soil temperature and moisture of the 0 - 15 cm stratum during 1986. 37 % Moisture and Temperature C 2nd depth 1986 Moisture 16 Temperature C 20 30 i /\ .................. _ 25 /\ / \A J - 20 - 15 ....................................................... .............................. 0 I I I I j I I I I I I T I II 0 AAMMJJJJAASSOONND 11111111111111111 5 5 5 5 5 5 5 5 date — 96 Moisture —i— Temperature C Figure 6. Average recorded soil temperature and moisture of the 16 - 30 cm stratum during 1986. 38 1.2. 5.911.821.5521: Percent soil moisture under different grass covers for the two depth strata is given in Table 3 and 4. Since statistical analysis ( two-way analysis of variance ) revealed no differences among grass blocks, but soil moistures differed with sampling dates, data presented in Figures 3, 4, 5, and 6 are averages derived from all grasses in 1985 and 1986. In 1985, the driest period occurred between July 1 and August 15 at both depths. Percent soil moisture ranged from 4.1% to 22.2% in 1985, while in 1986 it ranged from 9.1% to 24.4%. Overall, 1985 was drier than 1986. 1.3. W Rainfall is presented. as totals for the: two weeks preceding sampling dates (Figure 7). In 1985 the periods of April 16 to May 1 and June 16 to July 1 were drier than in 1986, with precipitation ‘totalling 0.48 cm, and 0.58 cm respectively. In general, lower rainfall resulted in lower soil moisture at all depths in 1985 (Figures 3 - 6). The driest period in 1986 occurred between October 16 and November 1, with 0.8 cm rainfall. 39 20 15 w 5 Eu 20. 02 3:5 fly :5 .2. 1 633 0 4| 5. .u mO— |>OZ£ .>OZm—I .>ozm ..z.ipr_ HUD m-iw UO~ HUO pimmmwp .me 91¢me mum 702m— .OD< 9.09% 86. —i..5_..w— 15.. 91.52 JDH 7233. 233—1232 231229 >32 m_l><2~ >42 Wanda— .m n2»... Tam/R .. . . 74.37%. \J‘“ nu Amount of precipitation received in the study area during 1985 and 1986. Figure 7. 40 The four orders of Acarina, Prostigmata, Mesostigmata, Cryptostigmata and Astigmata, occurred under all six species of grasses at Hancock Turfgrass Research Center. The relative numerical distribution among these mite orders (Table 5 and Figure 8) in 1985 and 1986 revealed that Prostigmata were the most dominant, followed by Mesostigmata; Cryptostigmata ranked third and Astigmata were the least dominant in both years. It is also clear (Table 5) that the density of Acarina in 1986 was doubled over 1985: this may be related to the fact that 1985 was hotter and drier than 1986. 8W Prostigmatid mites were the most prevalent group present under turfgrass in the study area. Within this order in which basic body morphology is subject to diverse modifications, four suborders (cohorts) were recorded. The suborder Heterostigmata was most dominant, followed by Eupodina; Endeostigmata and Raphignathae were found in very low numbers. 41 Table 5. Relative dominance of Acarina orders in 1985 and 1986. 1985 1986 Mite orders N % N % Prostigmata 4006 63.8 11456 83.0 Mesostigmata 1690 26.9 1201 8.9 Cryptostigmata 498 7.9 798 5.9 Astigmata 88 1.4 83 2.2 Total 6282 13478 N = the total number of specimens obtained per year. 42 .Aomoss mummoum Hap. mumpuo ocuumoo up Any mocmcuaoo u>~us~wm .m macawh ©®®— mmwmfl 89:950on @om 55:950on mm 05 30 MW w azm< 72..., 2: \\ $589691 SoEmzwoi mtooto 9:2 4:3. B-l. Wm: Split-plot analysis of variance of prostigmatid counts revealed no significant differences (p > 0.25) between grasses in 1985 (Table 6 and Figure 9). For 1986, analysis showed very marginal differences (p < 0.25) between grasses in accommodating prostigmatid populations. For both strata combined, smooth bromegrass harbored the highest numbers of Prostigmata (28100/m2), followed by Kentucky bluegrass (24650/m2); the extensive root system and vigorous fleshy rhizomes of these two grasses may provide rich habitats for prostigmatid populations. Tall fescue harbored the lowest population (10450/m2); this grass also has an extensive root system, but it can penetrate to depths below 40 cm: the rhizosphere. of tall fescue may' therefore not. have been completely sampled in this study. 3.2. 3 W“. ‘2 --. 01‘ e 92- °Il!-.,,°_ .009- '_ '1‘ Date effects were significant at p <0.001 in both years (App. B). Although overall numbers of prostigmatids were more than doubled in the second year of the study, seasonal abundance patterns of 1985 (Figure 10) were repeated in 1986 _(Figure 11) . Density maxima occurred in July and October, followed by population declines in late fall. Increased rainfall in 1986 seems to have been a contributing factor toward larger populations in July of that year; its effect 44 Table 6: Population densities $SE/mz of Prostigmata in each soil stratum under different grasses. 1985 1986 0 - 15 cm 16 - 30 cm 0 - 15 cm 16 - 30 cm Grasses Mean SE Mean SE Mean SE Mean SE ==s 2.====.=.======._..==_. 4- Sm. bg 4900 $700 3700 $1050 8800 $1550 19300 $8950 Ky. bg 4350 $700 2750 $ 450 16750 $8650 7900 $1150 Ordgrs 5050 $800 1750 $ 350 5650 $ 800 7450 $1800 Timthy 3550 $500 1950 $ 300 8450 $1200 8200 $1600 Tl Fse 4400 $950 2350 $ 450 4950 $ 900 5500 $1300 Redtop 4250 $700 2800 $ 550 9750 $2550 9600 $2700 N = 48 for 1985, 51 for 1986 45 Order Prostigmata 1985 - 0-15 cm \\\\‘ 16-30 cm Grass Species 1986 Density (Thousands) 20 1 - o-15 cm 15-30 cm 16 ................ 10 . ............................ 5 . ..... 0.. arms. K. B. Orch. Tim. T. F. M19 Grass Species Figure 9. Prostigmata densiti 2 ' - . es /m in both soil str different grass covers. ata under 46 was then amplified in a second wave of reproduction which led to an all-time population peak of 87700/m2 on October 1 (Figure 11). 8.3. W: Using lumped data from all grasses, split-plot analysis of variance (App. B) showed highly significant depth effects for prostigmatid populations in 1985 (p < 0.001). On all sampling dates, Prostigmata were more numerous in the 0 - 15 cm stratum than in the 16 - 30 cm layer (Table 7, Figure 12) . As previously mentioned, precipitation was low throughout 1985 and did not penetrate deeply, as evidenced by low soil moisture (Table 3). Higher moisture in the upper stratum, and its potential effect on the mites' food sources (fungi and bacteria), were probably the main driving variable for prostigmatid distribution. For 1986, statistical analysis (App. 8) showed no significant difference between depths. Prostigmatids occurred in almost equal densities in both strata. Occasionally, populations were higher in the 16 - 30 cm stratum, on dates when soil temperatures were high (Table 7 and Figure 12) . Higher precipitation in 1986, penetrating deeply through both sampled strata, apparently resulted in relatively even mite distribution. Table 7: Mean seasonal density /m2 47 $SE of Prostigmata in upper and lower soil strata; data from all grasses lumped. ===l 1985 1986 0 - 15 cm 16 - 30 cm 0 - 15 cm 16 - 30 cm Dates Mean SE Mean SE Mean SE Mean ' SE Aprl 1 --- --- -7- --- 10100 $ 3650 8000 $ 2400 Aprl 15 4550 $1350 2650 $ 750 2600 $ 700 2700 $ 1000 May 1 3250 $ 750 1950 $ 550 2600 $ 500 1650 $ 350 May 15 4600 $ 900 1600 $ 500 2650 $ 900 1250 $ 450 June 1 5250 $1050 2450 $ 750 4400 $ 1100 3900 $ 1100 June 15. 5050 $1150 2550 $ 750 9950 $ 1700 17050 $ 3200 July 1 8850 $1700 4350 $ 950 8200 $ 2000 9900 $ 2550 July 15 5850 $1400 3300 $1000 21550 $ 5450 25000 $ 3000 Aug 1 3600 $ 750 1400 $ 250 13700 $ 2050 14000 $ 3450 Aug 15 3450 $1300 1600 $ 500 10450 $ 1850 10150 $ 2450 Sept 1 2050 $1000 1650 $ 450 4350 $ 1250 5050 $ 900 Sept 15 2700 $ 700 900 $ 200 10350 $ 1350 6650 $ 1400 Oct 1, 6050 $ 950 4000 $ 950 37350 $24400 50350 $24950 Oct 15 5700 $2100 5200 $2500 - 5800 $ 1500 4550 $ 1100 Nov 1 3200 $ 950 2600 $ 800 5050 $ 1400 2050 $ 250 Nov 15 3400 $ 650 3150 $ 900 2800 $ 600 1350 $ 350 Dec 1 3400 $ 900 1200 $ 500 2100 $ 800 750 $ 150 N = 18 per date and depth 48 Order Prostigmata 1985 density (thousands) ‘14 3:- ________ /\ H 4 H 2 ............................... OIIIIIFIIfiIITIII AAMMJJJJAASSOONND 11111111111111111 5 5 5 5 5 5 5 5 date Figure 10' Biwa9kly fluctua tion of Pro grasses combined. Stigmata during 1985' all 49 Order Prostigmata 1986 density (thousands) 100 80 _ ....................... . ......................................... 60 ........... . 7: 20 A22 -‘J> cn-43» 4 .13: m Ch-‘i: 5 .1t. d -Ac. (”=1‘_ - 0.4:. A date Figure 11. Biweekly fluctuation of Prosti gmata during 1986, all grasses combined. “ 50 No correlation between abundance and temperature could be obtained for either depth and either year; i.e., large populations during hot as well as cool seasons (Figures 10 and 11) were most likely the result of inherent reproductive patterns, irrespective of temperature. For the 0-15 cm stratum, but not for the lower layer, positive correlations to soil moisture existed in both years. Together with the between-year differences discussed above (upper stratum preferred by Prostigmata in 1985, when rain did not penetrate deeply), this indicates that moisture was a significant determinant of vertical distribution. With respect to potential effects of grass types, split-plot analysis of variance showed significant interaction among grass types, sampling dates and depths in both years. Grass-specific population means for each date and depth were then compared ( App. A) using Tukey’s 95% MSD. For 1985, mean abundance of Prostigmata under orchardgrass in the upper soil stratum on July 1 was significantly different only from that under smooth bromegrass. On October 15, mite density under tall fescue was higher than under all other grasses (Figure 13). In the lower soil stratum during 1985, there were no differences between population densities under the six grasses, with one exception: on October 15, mean density under smooth 51 OnhrPnuMumns «nus “NM I“- mas-Ce- ‘~“. V““~.‘t‘. o \~“~‘~ ‘\r‘.‘~“““‘~ ““““‘~ 0“ " .‘“\ . V“\ m i V“:‘““\ , V““.‘““| l1 ‘-‘~“ V““~\ “ “‘L ““‘\ on... It s - e e u r .‘-“\0 d d 3 o ‘ ‘ pone. 0' “I. "1- o... 0‘ .7. .1- A1... A1. Iv“ Ive- J1. Ice- “a... u.- ‘1. A' “MR dell-m W) unman— -o-Ce- Vertical distribution of Prostigmata during 1985 and 1986» all grasses combined. Figure 12. 52 bromegrass was significantly higher than all other recorded densities (App. A and Figure 13). In 1986, the only differences among densities occurred on October 1, when Prostigmata were significantly more numerous under Kentucky bluegrass (0 - 15 cm layer, Figure 14). In the lower stratum on the same date, mean population density was much higher under smooth bromegrass than under all other grasses (App. A and Figure 14). 53 Order Prostigmata 1985 0-15 cm density (x500) 36 30 26 20 ‘5 .. . . .. . . Mine 10 :2 g; 2;”: , i2: 1.1.? 5 :-: :-; :- '- :- . -:- -; -: -: '-: .. '- '- 0 AAMMJJJJAAOSOONND 13131113131313.1111 date 1985 16-30 cm density (x500) eeeee $1202 _ /l é I Kl'w'w AAMMJJJJAASSOONMD m ........... .......... ........,... I." n/I'Z /, I: ‘a‘gi‘i';3|nga§§‘ti -— _lu ln'lg'lwli i “91'“! ”fl 11111111 15151151515151.5151 date Figure 13. Mean seasonal densities of order Prostigmata under different grasses at each depth during 1985. 54 Order Prostigmata 1988 0-15 cm density (x500) soo soo zoo zoo 15° 2. 2. Rdtop 1oo I 1:11:15. 0 A A II.‘ J J J 11 A A1331: 0 C11! N D 11111111 15151515151515151 date 1986 18-30 cm density (x500) 4001 200“ — I .222. |_1_ .14 — — — . ‘jjr fl: 2'» “MAW ~“‘ 333“": 4.5119 mum" E51011”: luiji A Ail! M .l J J .l A Ail! 8 €113 N I! 0 11111111 16151516151616151 data Figure 14. Mean seasonal densities of order Prostigmata under different grasses at each depth during 1986. 55 OW Heterostigmata were dominant among prostigmatid mites. The suborder was represented by nine genera, two of which were most prevalent in both 1985 and 1986: W spp. and W spp. Table 8 and Figure 15 show dominance percentages of these two genera among .total Heterostigmata in 1985 and 1986. C.1. W3 W spp. constituted the highest proportion of Heterostigmata (37.4% in 1985 and 71.2% in 1986), with an approximately seven-fold increase in total numbers (Table 8). A possible cause for this increase in 1986 may have been higher precipitation and higher soil moisture, which allowed growth of fungal and bacterial colonies, the main food sources of the species in this genus. Further studies studies would be required to validate this suggestion. C020 -I‘ '7 ’ 1“ °V’ ‘ 'l 2'! " °_ :,‘°!‘l!_‘ ‘9...- Split-plot analysis of variance revealed very little difference (p <0.25) among grasses in accommodating maisonemns spp. populations in 1985. In 1986, there was no evidence at all of differences (p >0.25) among grasses. However, smooth bromegrass seemed to support the highest populations in both years, with 2250/m2 and 17150/m2 56 Table 8. Relative dominance of Heterostigmata genera in 1985 and 1986. 1985 1986 Genera N % N % Tarsonemus 891 37.4 6727 71.2 Bakerdania 395 16.6 446 4.7 Scutacarus ‘ 355 14.9 321 3.4 Other genera 743 31.1 1953 20.7 Total 2384 9447 N - the total number of specimens obtained per year. 57 , .oomu oco mama cw ouocoo puuosafiumououoc up .«v mococfieoo o>fiuo~om .mH shaman omae. . mmae moamwwsoow Ecumenism. o wwmo o @3 oaocwwmmofo fl-w m; c a E ////4. ,2 mnemoosoow ///////2 ///////\\\\\h moEocomzfl ego 569.038. 1 mcmEmzmotoEI 58 respectively (Table 9 and Figure 16). This may be related to the extensive, fleshy rhizome system of this grass which could promote fungal and bacterial colonies. Split-plot analysis of variance, using combined data from all grasses (App. B), showed highly significant differences (p <0.001) among population densities on different dates. In 1985, Tarsonemus spp. showed two prolonged peaks, one from early June until late July. The second peak occurred throughout October (Table 10 and Figure 17). In 1986, Tarsonemus spp. again exhibited two peaks, on July 15 and October 1 (Table 10 and Figure 18). The pattern observed in 1985 was thus essentially repeated in 1986. C.4. ‘1 e_ 9 9- on O’ a Ol‘u-‘ 9° 90!- . 01?: Highly significant density differences (p <0.005) with depth occurred in 1985, but not in 1986 (p >0.50) (App. B). In 1985, Tarsonemus spp. were found in higher numbers in the upper soil stratum throughout most dates (Table 10 and Figure 19) possibly related to low precipitation and insufficient penetration of water into soil. In 1986, although depth was not a significant factor, higher abundances were recorded for the lower soil stratum on 7 out Table 9: Population densities $SE/m’ 59 Of Tarsonemus SPP- in each soil stratum under different grasses. 1985 1986 0 - 15 cm 16 - 30 cm 0 - 15 cm 16 - 30 cm Grasses Mean SE Mean SE Mean SE Mean SE =——=========L ===a============================== Sm. bg 1400 $450 850 $250 3000 $600 14150 $8000 Ky. bg 1050 $250 550 $150 10850 $7350 3650 $650 Ordgrs 800 $150 450 $150 3050 $600 4250 $1450 Timthy 650 $150 450 $100 3850 $800 5250 $1300 Tl Fse 750 $150 500 $100 2400 $600 3000 $1050 Redtop 1000 $200 800 $250 5600 $2000 6850 $2300 N 8 48 in 1985, 51 in 1986 60 Genus Tarsonemus Density - 0-16 cm .\\\\‘ 16-30 cm SmB. KB. Oroh. Tim. T. F. ndtp Grass Species 1988 Density (Thoussnds) - o-15 cm \\\\\ 15-30 cm ‘ 8111.3. K.B. Orch. Tim. T. F. Rdtp Grass Species Figure 16. Tarsonemus spp. densities /m2 in both soil strata under different grass covers. 61 Table 10: Mean seasonal density /m‘ $SE of Tarsonemus spp. in upper and lower soil strata: data from all grasses lumped. 1985 1986 0 - 15 cm 16 - 30 cm 0 - 15 cm 16 - 30 cm Dates Mean SE Mean SE Mean SE Mean SE Aprl l --- --- --- --- 800 $250 800 $250 Aprl 15 1000 $450 950 $400 350 $100 850 $650 May 1 900 $300 400 $150 400 $200 200 $100 May 15 1000 $250 300 $100 700 $250 550 $300 June 1 1350 $300 1150 $450 1850 $750 1400 $400 June 15 1950 $650 800 $300 4700 $1100 9950 $2350 July 1 1350 $300 1500 $300 4800 $1300 6650 $2100 July 15 1450 $700 1150 $500 15350 $4150 17900 $2400 Aug 1 300 $250 200 $100 6100 $1400 10200 $3250 Aug 15 100 $ 50 100 $ 50 3800 $850 6150 $2150 Sept 1 1100 $850 450 $200 1200 $500 850 $350 Sept 15 450 $300 150 $ 50 5350 $950 4000 $950 Oct 1 1200 $300 650 $200 30500 $20700 42950 $22250 Oct 15 1150 $250 650 $300 2050 $600 1450 $300 Nov 1 650 $200 600 $150 2600 $1150 850 $150 Nov 15 800 $200 450 $300 1000 $350 300 $150 Dec 1 200 :100 100 1 so 200 1100 150 :50 m N: 18 per data and depth 62 Genus Tarsonemus 1985 density 3000 2500.4 ...................... 7 .......... 2000.. ......................................... 15004 2- ................................................................ 1000—i ........................................................................................................................................................ 500... ................................................... . ............................................................................... it 0 I T I I I r I I I I I I I I I AAMMJJJJAASSOONND 11111111111111111 5 5 5 5 5 5 5 5 date Figure 17. Biweekly fluctuation of Tarsonemus spp. during 1985, all grasses combined. 63 Genus Tarsonemus 1986 density (thousands) 8O 60 .1... .............. 40.. ............. (n-sc. — date Figure 18. Biweekly fluctuation of Tarsonemus spp. during 1986, all grasses combined. - ' 64 Gumn1hnnwumn 1mm '7 u llama Elena- ‘1 "WV“\ 1‘~“‘\ 1 I “‘~“\ p‘.‘“‘~t . s " 1“~\ \‘ i‘t‘k t ‘ “‘-~““‘- ““‘~‘\ V-----S .“L " “‘.‘. . V“~‘~‘~‘~ m m a q a m m 0 ' 0e... (“wanna-a) -e-e a five-0e. Ilzflgngmng spp. during 1985. , all grasses combined. Vertical distribution of and 1986 Figure 19. 55 of 17 sampling dates. However, it seems that W spp. freely inhabited both strata in 1986 because of more evenly distributed moisture (Figure 19). Soil temperature and moisture were not correlated to abundances at either depth, indicating that density changes were probably due to seasonal events of reproduction and mortality inherent in the members of this genus. Anova. (App. B) of' densities under’ each turfgrass revealed very little interaction (p<0.25) between grasses and dates in 1985 and none at all in 1986, although abundance estimates for either stratum differed between grasses on several dates. In general, significantly higher densities occurred mainly under smooth bromegrass and Kentucky bluegrass (Figures 20 and 21) , again indicating that these grasses provide advantageous below-ground habitats for' Tarsonemus spp. Although overall abundance appeared modulated by grass species, lack of grass/date interaction points out the basically similar seasonal fluctuation patterns of Tarsonemus spp. under all grasses. C-S. W C.6. 7‘ 0 - ass 0 ‘ 01 0’1‘ “ - =z.‘ 211°: 99. Split-plot analysis of variance showed highly significant differences (p <0.001) between grasses in 66 Genus: Tarsonemus 1985 0-15 cm density (x500) 1985 ' 16-30 cm density (x500) 1° - ...-:3. ......-.. ll 8 «FE . -!|l— . . - I IL. " 4 as"... _. ; :ZII-— II-i'I-J—I =17I— ?I!-I-‘—‘—/ I!I_ _ l7]:;//jg IA? ... / 1w .114—711:. F.” 2 .1"... _ {ALI/Ea Z 3:; I‘m 7: ..—.. 'mi — "UTmthy ‘ u—eI .mI -n'l . a! E :1: lg. ‘0': I I fiI—ir Wong. aa-I 'I' --‘==-' 5 282039 0" AAMMJJJJAASSOONND 1 1 11111 1 15151515151516151 date Figure 20. Mean seasonal densities of Tarsonemus spp. under different grasses at each depth during 1985. 67 Genus: Tarsonemus 1986 0-15 cm density (x500) 300 250 ' 200 150 a,‘,=, 100 “.5” =:::’ =:’ 4954:: =5: = 5:6 ' ' a AAMMJJJJAABSOONND 11111111 16161616161616161 date 1986 16-30 cm density (x500) ............................... 350 300 ', .................... 250 ’3 200 ” . A 15° =-.‘;: i 42:5 Rd!” 100 6:: =7 3?; 5: ‘I’lFo , =7 5 a :1: a a a Tillflly 6° . 4:: = =7 .; ._ a a a cue. O a = ' " " a a a a W 59 Saba AAHMJJJJAABSOONND 11111111 16161516161616151 data Figure 21. Mean seasonal densities of zgxggngmgg spp. under different grasses at each depth during 1986. 68 supporting W spp. populations in both 1985 and 1986. The highest abundance of figkggggnig spp. was recorded for Kentucky bluegrass with 1300/m2 and 1750/m2 in 1985 and 1986 respectively, possibly related to the extensive root system of these species. The lowest population density was recorded for redtop, the species with the deepest-ranging root system of all grasses investigated (Table 11 and Figure 22). Densities of Bakerdania spp. differed between dates in 1985 and 1986 (P <0.001). Highest abundances were recorded at the beginning of each season (2000/m2 in 1985 and'ZSSO/m2 in 1986) , followed by moderate fluctuations throughout the rest of each year. On December 1, increased densities of 1450/m2 in 1985 and 1100/m2 in 1986 were again recorded (Figures 23 and 24), indicating a pattern consistent between years. C.8. ‘1 — 0. ‘ .-_ 0! 0 :._1- 0...!-_ ‘90 .009- -_ 01:. Vertical distribution of the genus differed greatly (p <0.005) with depths in both 1985 and 1986. W spp. preferred the upper soil stratum throughout all dates except on June 1, June 15 and September 1 in both 1985 and 1986 (Table 12 and Figure 25). 69 Table 11: Population densities $SE/ma of Bazerdania spp. in each soil stratum under different grasses. Grasses Sm. bg Ky. bg Ordgrs Timthy Tl Fse Redtop N = 48 for 1985, 51 for 1986 O - 15 cm Mean 800 550 500 300 300 150 SE 3200 i200 i100 1100 i100 $100 16 - 30 cm Mean SE 300 $50 750 £200 100 £50 100 :50 200 :50 50 :50 m 1986 0 - 15 cm 16 - 30 cm Mean SE Mean SE 500 1150 350 :100 1200 1350 550 :150 200 $100 so :50 750 :250 250 :100 250 :150 so —- 100 :50 So :50 70 Genus Bakerdania 1985 0011117 1000‘ - 0-16 cm ““31960cm 800‘ 000 n’ 4°04, ........... suns. KB. Oven. Tim. 11?. Hip Grass Species 1986 1400 ‘ - 0-16 cm 1200 .. 15-30 cm 1000" .................... Sana. K.B. Oren. Tim. 1'.F. M19 Grass Species Figure 22. aakggggnia spp. densities /m2 in both soil strata under different grass covers. ll 1! 71 Table 12: Mean seasonal density /m2 :53 of Bakerdania spp. in upper and lower soil strata: data from all grasses lumped. 1985 1986 O - 15 cm 16 - 30 cm 0 - 15 cm 16 - 30 cm Dates Mean SE Mean SE Mean SE Mean SE Aprl 1 --- --- --- --- 1800 £600 750 i400 Aprl 15 1450 :550 550' :200 1050 :550 400 :200 May 1 150 £100 500 1250 550 £250 200 i100 May 15 650 £200 100 £100 150 £100 150 i100 June 1 150 £100 200 £100 400 £150 650 1250 June 15 200 £100 800 £400 100 £50 150 1100 July l 200 £100 150 £100 300 £150 250 i100 July 15 100 $50 150 150 200 1150 50 :50 Aug 1 100 $50 0 -- 250 £150 50 :50 Aug 15 250 £150 50 :50 750 $600 150 thO Sept 1 150 £100 200 £150 150 £150 200 i150 Sept 15 150 1100 0 -- 700 $400 150 thO Oct 1 550 1200 350 1150 150 t100 50 :50 Oct 15 750 £200 100 150 150 1100 50 :50 Nov 1 300 $100 200 $150 200 1100 50 :50 Nov 15 650 1200 250 1100 650 $300 400 i200 Dec 1 1100 1450 350 $300 1100 1500 O -- N = 18 per date and depth 72 Genus Bakerdania 1985 density 2500 2000~ 1500.. .................................. f 1000- 500 O IIIITTIIIITTITI AAMMJJJJAASSOONND 11111111111111111 5 5 5 5 5 5 5 5 date Figure 23. Biweekly fluctuation of Bakerdania spp. during 1985, all grasses combined. 73 Genus Bakerdania 1986 density 3000 2500 ..................... 2000.. ................................................................. 1500.. .............................................................................. 1000 «5CH3 \¥{ 0 TITIIVII.ITTITTI_ AAMMJJJJAASSOONND 11111111111111111 5 5 5 5 5 5 5 5 date Figure 24. Biweekly fluctuation of flaggzdanig spp. during 1986, all grasses combined. -H- mm.- 74 lei-117 “‘.‘~ u e- . Gnnann V t 0 1 NBC fl ‘-~‘\ lieu .9..- i J 1 I 1-\ a I. H .‘~“~ ‘ee. “““‘~‘\ ‘ ' “I! Vertical distribution of Bakerdania spp. during 1985. and 1986, all grasses combined. Figure 25. 75 Since populations tended to peak in early and late season of both years (Figures 23 and 24), it is not surprising that correlations between abundance and temperature were negative. In 1985, a significant relationship between densities and moisture of the upper stratum existed, partially explaining mid-summer population declines during this low precipitation year. Interaction between grasses, dates and depths was also significant. With a single exception (smooth bromegrass), date-specific comparisons strongly indicated that Kentucky bluegrass supported the largest numbers of Bakerdania spp. (Figure 26). On several dates in 1986, Kentucky bluegrass again proved superior in terms of abundances of Bakerdania spp. (Figure 27). 76 Genus: Bakerdania 1985 0-15 cm density (1:500) 10 , ‘ .1 E 65:64:7- 5 - Ramp '1 E a . T Ttth. ':_ z e e L m y 2 if: 2 _ g . a : '_ 011195 0 f1 Tfi I F1 I I rfigi l r l r 1 8059 A A u M J J J J A A s s o O N N o 1 1 1 1 1 1 1 1 1 5 1 5 1 5 1 5 1 5 1 5 1 5 1 5 1 date 1985 16-30 cm density (x500) 8 .1 ’: ...................... ‘ '7': I; a a- 2 131.7355 I E E a ... :9 =7 fizz—=72: “6'09 . : 1 ==4=r¢=r==.31r=. 2 "F. 2 -- ° : ° . . g, ._._, as: : :: mm! 333 .. : i :1: 23:3 a ‘5' E31 .-::3:1 I: ”0:295 0 f I. l.' Tat, I. I. Friar r [:5 I. I I. 1:3“!09 .A A M M J J .I.J A A s s o o u N D 1 1 1 1 1 1 1 1 1 5 1 5 1 5 1 5 1 5 1 5 1 5 1 5 1 date Figure 26. Mean seasonal densities of Bakerdania spp. under different grasses at each depth during 1985. 77 Genus: Bakerdania 1986 0'15 cm density (x500) 1°? .1. 3‘". E : g; ,. == ' = I m 4 ._E: E 5.: page , 1113.9 2.1313 {1% : :. : : . Tmthy 33E :3: 3 2 _ 2 . is :15; . : ”0:19. 0 1.1“Tal'VIIT I Tar. 1:??r f1. 1.. 1 8.09. A A M H J J J J A A 3 8 O O N N 0 1 1 1 1 1 1 1 1 1 6 1 0 1 5 1 0 1 0 1 0 1 0 1 6 1 date 1986 16-30 cm density (x500) ................... 0 .......... 5. ‘. 3‘ . Ham 2 "Fe 1 =5 Tmthy o =::.=:::==:ZI==' a‘ AAMHJJJJAASSOONND 1 1 1 1 1 1 1 1 15151515151515151 date Figure 27. Mean seasonal densities of Bakerdania spp. under different grasses at each depth during 1986. 78 D. Suborderi_fiungdina The suborder Eupodina (excluding the family Tydeidae which is treated separately in this study ) was represented by 5 genera: Ennodes spp.. Qoscenngdes spp-. Bhagidia spp.. gggggxnggidia spp. and Ezgyngtgg spp. The relative dominance of these genera recorded in Table 13 and illustrated graphically in Figure 28. The genus W was dominant with 55.7% and 45.5% in 1985 and 1986 respectively. D-l. Bffe9t_9f_srass.292srs.2n_densities_2f Ennodes sun»: Grass cover had a significant effect (p <0.001) on Eupgggg spp. populations in 1985. The highest densities were obtained for orchardgrass with 850/m2 followed by tall fescue *with 700/mz, while ‘the lowest abundance occurred under redtop with ZOO/m2, (Table 14 and Figure 29). In 1986, no significant differences among grasses existed. However, the highest density now occurred under redtop with 4OO/m2 while the genus was essentially absent under Kentucky bluegrass (Table 14). 0-2 Bigeeklx_flu9fuafi2n_2f_Bupgdes_§nni_pgnnlatigns= As shown in Figure 30 and 31, We: spp.abundances varied greatly over each season (date effects significant at p <0.001). Population peaks were observed in July of 1985 and August of 1986, with occassional complete disappearance 79 Table 13. Relative dominance of Eupodina genera in 1985 and 1986. 1985 1986 Genera N % N % Eupodes 301 55.7 137 45.5 Cocceupodes 97 18.0 50 16.6 Rhagidia 94 17.4 44 14.6 Coccorhagidia 16 3.0 2 0.7 Ereynetus 32 5.9 68 22.6 total 540 301 N a the total number of specimens obtained per year. 80 .wmmd 0:5 mama ca chocoo ocfipomom uo Aav monocusoc o>uuo~om .om Guamfim ©®©P mee No .5800 0.3 .923 v.2 .omcm . F onoooo 9mm .55 m o m ..ooooo .2 0.9 9.0 >oem.‘ mocooaooooo of. 8685 So 8585 mEcoozm. 81 Table 14: Population densities $SE/mz of Eupgggg spp. in each soil stratum under different grasses. 1985 1986 0 - 15 cm 16 - 30 cm 0 - 15 cm 16 - 30 cm Grasses Meanfid__SE_~Mean__ SE f Mean” ___SE _Mean SE Sm. bg 300 £50 50 :50 150 £100 0 -- Ky. bg 450 £100 50 -- 50 -- 50 :50 Ordgrs 850 £200 0 -- 150 :50 O -- Timthy 400 :150 so ' -- 250 $100 so -- Tl Fse 700 £200 50 :50 250 :50 50 -- Redtop 200 :50 50 150 400 1150 O -- N 8 48 for 1985, 51 for 1986 82 Genus Eupodes 1985 0011th 1000 " - 0-16 cm \\\\‘ 15-30 cm .............................. 8111.8. Ice. Otch. Tim. 1’.F. Rdtp Grass Species 1986 500- - 0-15 cm 15-30 cm 400:: 300: 200«- 100‘, .......................................................................... OJ 8111.3. K.B. Orch. Tim. T.F. Rdtp Grass Species Figure 29. Egpgggg spp. densities /m2 in both soil strata under different grass covers. 83 Table 15: Mean seasonal density /mz $SE of Eupodes spp. in upper and lower soil strata: data from all grasses lumped. 1985 1986 0 - 15 cm 16 - 30 cm 0 - 15 cm 16 - 30 cm Dates Mean SE Mean SE Mean SE Mean SE Aprl 1 --- --- ‘--- --- 200 £100 50 :50 Aprl 15 150 2100 o -- o -- o —- May 1 150 2100 50 :50 100 :50 . 100 :50 May 15 350 £150 100 1100 100 £100 0 -- June 1 1100 £350 0 -- 50 :50 0 -- June 15 400 £150 100 150 0 -- O -- July 1 1850 £550 50 £50 150 $100 0 -- July 15 950 £250 0 -- 200 £100 50 :50 Aug 1 300 £150 50 :50 650 £200 50 :50 Aug 15 700 $200 50 :50 1050 £450 200 1100 Sept 1 200 1100 o -- 350 1150 o I-- Sept 15 350 1150 0 -- 200 £100 0 -- Oct 1 250 1100 O -- 50 :50 O -- Oct 15 300 £100 50 :50 50 150 0 ~- NOV 1 200 $150 0 -- 50 :50 O -- Nov 15 200 £100 50 £50 200 £100 0 -- Dec 1 400 ‘1200 100 1100 150 1150 O -- N 18 per date and depth 84 Genus Eupodes 1985 density 2000 1500.. ........................... 1000.. ......................... , ................. _ ................................... 500 0 ITIITJIFTIITITI AAMMJJJJAASSO-ONND 11111111111111111 5 5 5 5 5 5 5 5 date Figure 30. Biweekly fluctuation of Eupodes spp. during 1985, all grasses combined. 85 Genus Eupodes 1986 density 1400 Til ilililiIiT AAMMJJJJAASSOONND 11111111111111111 5 5 5 5 5 5 5 5 date Figure 31. Biweekly fluctuation of Buggies spp. during 1986, all grasses combined. . ‘ 86 (Figure 31) . In both years, maximal abundances coincided approximately with the highest temperatures of the season (Figure 3-6). D.3 WWW: Statistical results indicated a pronounced vertical stratification for the genus (p < 0.001). Throughout all dates, Eupodes spp. were found in much higher densities in the upper soil stratum (Table 15 and Figure 32). Zero counts were frequently recorded for the lower stratum (on 43% of all sampling occassions in 1985, and 59% in 1986). Clearly, Eupodes spp. were upper soil dwellers. Consistantly, in both years and at both depths, population abundance was positively correlated to temperature and negatively to moisture (App. C). These temperature relations simply indicated that the genus was not adversely affected by high temperatures, allowing population maxima to occur in mid-season. Grass-specific seasonal abundances (Figures 33 and 34), tested by Tukey's MSD (App. A), showed no differences between orchardgrass and tall fescue for the upper soil stratum. On several dates, however, these two grasses supported significantly higher populations than any other turf species. Orchardgrass and tall fescue thus seemed to provide the best habitats for Eupodes spp. In the lower soil 87 Guuofiumxno 1985 don-In an - a m“.- an ‘a ‘ II...IIOIDO”O.“QJIOI coo...- mqmn ................................ l i (J r l s -. l _ _S AAUIJJJJAAIIOGNNI 11111111111111!!! I I I I I I I I “MI “I! an -I-i- flit-ao- Figure 32. Vertical distribution of Engage; spp. during 1985. and 1986, all grasses combined. 88 Genus: Eupodes 1985 0-15 cm density (x500) 12 1o ” ON‘O. AAHMJJJJAASSOONND 11111111 16161618151515161 (flue 1985 16-30 cm density (x500) 0.. .- 0.’ ' 0.. . 0.. . 0.3 .- "i 'I - av - - a, - a 1116.“, . a 1- a a 4:: a a :7 =7 0'2 g 3;? - - - - - - - - T11"!!! 0.1 ’ - - 7 - - - - - - 0 eaaaj‘ 2:: =7: 2' aaaaaa W59 A A u n J J J J A A a a o o a u o 1 1 1 1 1 1 1 1 1 o 1 a 1 c 1 a 1 a 1 o 1 o 1 a 1 data Figure 33. Mean seasonal densities of Enpgggg spp. under different grasses at each depth during 1985. 89 Genus: Eupodes 1986 0-15 cm density (x500) 7 G 5 4 2 " _ ==¢= 'nro - 4' , -- Tum, 1 - -- -- 0 ca: gag" " a gag: AAMHJJJJAACCOONND 1 1 1 1 1 1 1 1 15151516151315151 date 1986 16-30 cm density (x500) 1.2 a ‘ db .. '. , ........ . . . . , ... '3' ...' : 0.. «in ..V '4 ................................ : ‘. _. _. , ...' ..I.' .' p: 0.. .h >: .' >0 ' O o ‘ ..n. . c - - - : ' 3 a 4:? a a a a A: . D 9 0‘2. ° -------aljl° ------- om. aaaaaaaaa " 55:55:75 ”.9 o- 8- DO A A U H J J J J A A 8 8 O O N N D 1 1 1 1 1 1 1 1 1 5 1 5 1 5 1 5 1 5 1 5 1 C 1 C 1 6816 Figure 34. Mean seasonal densities of Eupodes spp. under different grasses at each depth during 1986. 90 layer, poorly populated by these mites, no grass specific differences existed. B. Family: Tydeidae The classification of this family is in a state of flux. Most authors recognize 25 genera and more than 200 named species. It is unclear whether species complexes with discrete patterns and habitats exist or whether they are ubiquitous and nearly omnivorous. Tydeidae can be predacious, fungivorous or facultatively phytophagous and have a cosmopolitan distribution (Kethley 1982). In this study the family Tydeidae alone comprised 15.4% (1985) and 10.0% (1986) of all prostigmatids, and was the dominant family in the suborder Eupodina. Two species of this family occurred regularly throughout most sampling dates, in both years= Mess (Lam) Wiesel; Evans and W W Treat. Dominance of these two species within the family was 33.5% and 25.4% for I. W and 29.5% and 29.3% for M- We in 1985 and 1986 respectively (Table 16 and Figure 35). E.1. “' 0' 0 2‘ OV‘ ‘ 0! 909. a 01 Q tau. ‘ Of t‘u In both years, grass type significantly affected population densities of I. W. Redtop supported the highest numbers (approximately 700/m2) (Table 17 and Figure 36). Redtop has a root system which is regenerated 91 Table 16. Relative dominance of species in the family Tydeidae in 1985 and 1986. 1985 1986 Genera N % N % I. bedfordiensis 185 33.5 281 25.4 n. lggggnippggs 163 29.5 324 29.3 other species 205 37.0 500 45.3 Total 553 1105 N a the total number of specimens obtained per year. 92 1 , .owmn use mood : meowmoxa no mwdowmw omuowamm uo Aw. oococuaoo m>wuoumm .mn wusvfim .2 ©ma_ mwa_ 9: $6on $50 3.0on 650 m . ow momQQEooog mimEocotQEmE A .2 q 2 n .2 1 momQQEooo$ mtmcmuouocomo $26232me moemEmcouQSmE mambfi womb? mam—goo? ”3:5“. 93 Table 17: Population densities $SE/ma of Tyggus bggfgggiegsjs in each soil stratum under different grasses. 1985 1986 0 - 15 cm 16 - 30 cm 0 - 15 cm 16 - 30 cm Grasses Mean SE Mean SE Mean SE Mean SE Sm. bg 250 :50 ‘100 :50 150 :50 200 :50 Ky. bg 150‘ :50 100 :50 150 :50 150 :50 Ordgrs 100 :50 100 :50 250 :100 I 100 :50 Timthy 150 :50 150 :100 200 :50 250 :100 T1 Fse 100 :50 150 :100 300 :100 350 :100 Redtop 450 :200 200 :100 400 :100 300 :100 .=.............=......... _..._. N - 48 for 1985, 51 for 1986 94 Tydeus bedfordiensis 1986 Ouufly 500- - 0-15 cm 10-30 cm 400«' 30011 200‘, fiim 100‘“ ..... .1 0 " l I, 11F. Rd“: iansss'Spmxfles 1888 Danny 500- - 0-16 cm 15-30 cm 400« 300-~ zoo‘VWm 100-" “ O ' r—‘ L, ems. K.B. Gen. Tlm. 1’.F. m. GuassISpmmwss Figure 36. Tygggs bedfordiensis densities /m2 in both soil strata under different grass covers. 95 annually and thus leaves plenty of plant residues which may support fungal colonies, which may be the potential food sources for T. 12551311112115.15- E-2- W m: Population densities of I. W differed greatly (p <0.001) over time in both years. In 1985, highest abundance occurred on July 1, with pronounced lows or complete absence in the fall (Figure 37) . The pattern was repeated in 1986, although the summer peak was more prolonged and slightly bimodal (Figure 38). The species was thus most numerous during hot and dry periods, dramatic mid- season increases most likely being due to a single maximum in reproductive activity. E.3. WWW: Megs bedfordiensis populations essentially did not differ between depths (Table 18 and Figure 39), showing no persistent preference for either soil stratum. As expected in view of the species’ mid-summer population jpeaks (Figures 37 and 38), relations between abundances and edaphic factors were analogous to those encountered in Eupodes spp.: consistently, populations at both depths were positively correlated to temperature, and negatively to moisture (App. C). 96 Table 18: Mean seasonal density /m2 $SE of Iyggus bggjgggigflggg in upper and lower soil strata; data from all grasses lumped. 1985 1986 0 - 15 cm 16 - 30 cm 0 - 15 cm 16 - 30 cm Dates Mean SE Mean SE Mean SE Mean SE Aprl 1 0 -- o -- 100 :50 100 :50 Aprl 15 300 :100 100 :50 50 :50 100 :50 May 1 300 1150 150 £100 100 :50 100 :50 May 15 250 :150 100 :100 100 :50 0 -- June 1 100 :100 0 -- 150 :50 200 :50 June 15 ' 0 —- 50 :50 650 :250 850 :300 July 1 1000 1500 850 £350 500 :250 350 i100 July 15 200 £100 150 :50 650 1200 600 :250 Aug 1 350 £100 200 £50 1000 £300 400 :250 Aug 15 200 :100 150 :100 300 :100 300 :100 Sept 1 0 -- 0 -- 50 :50 400 :150 Sept 15 50 :50 150 :100 50 :50 100 :100 Oct 1 150 :50 100 :50 150 :50 200 :100 Oct 15 100 :50 50 :50 100 :100 50 :50 Nov 1 50 :50 0 -- 0’ --0 100 :50 Nov 15 50 :50 0 -- 100 :50 0 -- Dec 1 100 :50 0 -- 50 :50 50 :50 18 per date and depth 2 i u: 97 TYde U5 bedfordiensis 1985 density 2000 1500 1000 500 date Figure 37. Biweekly fluctuation of Ixfigns bedfordiensis during. 1985, all grasses combined. 98 Hide U5 bedfordiensis 1986 density :_ [I / 1 \ / / EH30 _ .......... 160C)" .............................................. 400 /‘ Clo—(q _ 0—0 g. _- O'lrdm _- date Figure 38. Biweekly fluctuation of 219:3: hggfgxgigngig during 1986, all grasses combined. 99 nubulbanEMMuuu 1986 an!" -o-uc- ESSIu-uca 1200 m qp-oo-~auuuuun see.- .. ...... a“ ‘ e... .u . ‘4 D II ".... I I. 0.... o la '1‘ ' Is All ‘ II 11... l- I. .J 1. U1! I I All A ... 1986 density Gnu-um -Hle. ‘ K “\ “ “s “l m V“.‘ ‘1“‘. ~|W~1~LU hill 1 m ‘~“L‘.‘“\ 11111111111111 “-‘~‘L ‘-‘.--‘~““-§ . 1“~ m 1 W .‘8 1111 ‘~\ ‘ eqoeeeeeeeee on I 1300 1000 I“ " w q pus-OIOUOIIO'eIIII ee-ee e D .I "In. N I. 0.1. o ..e .1. ‘ | All A I .41. ..- I. Idle. ... I. III H I A1. A ... during Vertical distribution of Tyfigns Figure 39. 1985 and 1986, all grasses combined. 100 Tydeus bedfordiensis 1985 0-15 cm density (x500) - 101 s-5 5.1;" "'" as: 4:52:35 4:755 Ramp . r :7: a: ca: / TIP. 24.- 33-- aaafiaga/ 1.111111, n.: Vi ----- - W“ I I I I f r I I I I I I I I r I I AAUUJJJJAA83°ONND 1 1 1 1 1 1 1 1 15151515151515151 date 1985 16-30 cm density (x500) 5— 31F-;I.x‘ 2"" a: -.-=/ R0109 a a aaaa/ T'F. 1-11- 5555/ TIIIUIY ‘ a C;C ‘- 13‘,» ’1;I_ --- ONO. 0 ‘ aaaaa i‘i' a: :=“ === “'ngg I I I I 7 I I T I I I I T if I I I A A H H J J J J A A 3 0 O N N D 1 1 1 1 1 1 1 1 15151515151515151 date Figure 40. Mean seasonal densities of rygggg bedfordiensis under different grasses at each depth during 1985. 101 Tydeus bedfordiensis 1986 0-15 cm density (x500) a 41 3 c1:- ....... 2 _‘_ - a E - a " " ‘Eynfl$”° 1:. ‘= =: . : a a 5", 1mm - ' 323 i , II- a mo 0 f I I I I I I I I F I I T I I I I a no A A u u J J J J A A s s o o N 1 1 1 1 1 1 1 1 1 s 1 e 1 s 1 a 1 a 1 s 1 s 1 s 1 (”Re 1986 16-30 cm density (x500) s 4 .3 ' i 2 .. a a as a - s-T'ermp “ :1 ans V a . a .1; . ‘ ‘ 5‘ a a 5 Int“? ‘ - =7 E11: ‘ TEUZ-aa ”or“. A A u M J J J J A A s s o o N N 0 1 1 1 1 1 1 1 1 1 s 1 5 1 a 1 s 1 a 1 s 1 s 1 a 1 (hue Figure 41. Mean seasonal densities of Tyggng bedfordiensis under different grasses at each depth during 1986. '102 Redtop was the only grass species singled out from all others in terms of supporting the highest densities of I. bggjgggignsig. On several dates, and more often in the upper than in the lower stratum, abundances were significantly higher under redtop (App. A, Figures 40 and 41). £04. --‘ 9 9 -“ 9V‘ ‘ 9! 1-11.9- ‘ 9.1- 2.9 91": In 1985, densities of M. lgggghippggg were almost equal under the six grasses. In 1986, weak differences (p <0.1) among grasses existed: Kentucky bluegrass supported highest numbers with a yearly mean of 800/m2, while lowest mean density was recorded under tall fescue (Table 19 and Figure 42). Much as in other mite taxa, seasonal abundance estimates fluctuated greatly during each year (p < 0.001) . Unlike other taxa, however, seasonal density patterns were highly discrepant between years (Figures 43 and 44). Early and late-season population lows provided the only points of similarity. Density maxima of 1985 occurred in July, while the. single pronounced. increase of 1986 was recorded in October. No explanations are readily apparent. One may speculate, however, that the species is physiologically (reproductively) flexible; and /or that changing below Table 19: Population densities +SE/m’ lgngghippgng in each soil stratum under different grasses. 103 Of MESQEIQDQEQEB§ I 1985 1986 0 - 15 cm 16 - 30 cm 0 - 15 cm 16 - 30 cm Grasses Mean SE Mean SE Mean SE Mean SE Sm. bg 200 :50 100 :50 500 :200 100 :50 Ky. bg 150 :50 50 :50 500 £300 300 :100 Ordgrs 100 :50 100 :50 300 +150 350 :150 Timthy 100 :50 250 +100 100 :50 450 :300 T1 Fse 50 :50 150 :50 50 :50 150 :50 N = 48 for 1985, 51 for 1986 104 Me tapronema tus Ieucohippeus 1985 Density 350 .1 - 0-160111 300 ‘“ 15-30 cm 200-- SS'“ 200-L §§ SS" 1501’ §§ §§“' i \M 50" ”u n 01‘ 1 . r r. *5 me. me. Oren. Tim. T.F. Mtp Grass Species 1988 Density 800- III 046¢m1 500 5‘ 16-30 cm 400‘. .......... 300‘, ........... ........... .... k 200-' 100. “I 1 ............ 01 8111.8. K.8. 0:011. 1111:. T.F. Rdtp Grass Species Figure 42. ugtgngngmgggg legggnippgns densities /m2 in both soil strata under different grass covers. 105 ground conditions under the six grasses, which had not been mowed or otherwise treated since May 1984, had some effect on this particular species. The latter interpretation is supported by a general shift in yearly mean densities, populations increasing under smooth bromegrass, Kentucky bluegrass and orchardgrass (Table 19). E.6 V‘fi. -_ . .0. 0! 0 v‘ -. oo‘u-_ .‘ ‘5 01 .09“ The species was distributed almost equally over depths in both years, although in July and August of 1985 the lower stratum seemed to be preferred (Table 20 and Figure 45). Given the mid summer peak of u. lguggnippeus in 1985, it is not surprising that densities were positively correlated to temperature, and negatively to moisture during that year (App. C). With no significant relationships emerging for 1986, it seems that the explanatory power of edaphic 'variables for’ either' densities or ‘vertical distribution was generally weak. With respect to grass-specific vertical distribution, no clear trends emerged. At either depth, and on several dates, populations were highest under any one of the six grasses (Figures 46 and 47). No clear preference for any grass species or grass related depth could be shown. Table 106 20: Mean seasonal density /m’ :58 of Metangggmaggg lgugghippgus in upper and lower soil strata; from all grasses lumped. data 0 - 15 cm 16 - 30 cm 0 - 15 cm 16 - 30 cm Dates Mean SE Mean SE Mean SE Mean SE Aprl 1 --- --- --- --- 50 :50 50 :50 Aprl 15 150 :50 so :50 50 :50 50 :50 May 1 100 £100 50 150 150 :50 100 :50 May 15 200 £100 50 :50 0 -- 50 150 June 1 300 :150 350 :150 o -- 50 :50 June 15 ’ 50 :50 150 :100 100 :50 0 -- July 1 400 :150 450 :200 50 :50 so :50 July 15 100 :50 550 :200 100 :50 150 :50 Aug 1 200 1100 200 150 300 £200 50 :50 Aug 15 100 :50 450 £300 100 1100 150 150 Sept 1 o -- 100 :100 850 :350 400 :150 Sept 15 50 £50 100 150 400 :150 200 1100 Oct 1 150 :50 100 :50 200 $100 650 :250 Oct 15 0 -- 0 -- 2050 $850 2150 1800 Nov 1 150 :50 o -- 300 :150 200 :100 Nov 15 50 :50 0 -- 50 150 0 -- Dec 1 0 -- 0 -- o -- o -- N 18 per date and depth 107 Metapronematus leucohippeus 1985 density 1000 ...- ................... ii .................................... 600 ............... 4c“)- ...................................................... 200... .......... V 0 I I I I I I I I I I I I ‘I r AAMMJJJJAASSOONND 11111111111111111 5 5 5 5 5 5 5 5 date We Figure 43. Biweekly fluctuation of during 1985, all grasses combined. 108 Metapronematus Ieucohippeus 1986 density (Thousands) date Figure 44. Biweekly fluctuation of Mesaprgngmatus lsngghinngufi during 1986, all grasses combined. 109 MenuommumnlusoMHMMI NE! “W -0-Ce- m0... “I! -§Iu ES“.- use 1000 AAHHJJJJAAIIOONND 1 11 11 11 11 11 11 11 11 I I I I I I I I dd. Figure 45. Vertical distribution of Metanrgngna§n§ leugghinnsns during 1985 and 1986, all grasses combined. 110 Metepronemstus Ieucohippeus 1885 0-15 cm density (x600) AAUHJJJJAAISOONND 11111111 1I1I1I1I1I1I1I1I1 date 1985 16-30 cm density (x500) 1A A u n J J .I.IIA1A I I 0 0 u N o 1 1 1 1 1 1 1 1 1 I 1 I 1 I 1 I 1 I 1 I 1 I 1 I 1 (ENG Figure 46. Mean seasonal densities of Metangngmatns under different grasses at each depth during 1985. 111 Me tepronema tus Ieucohippeus 1988 0-15 cm density (x500) 14 12 10 I . 41,-; a a :fi: - Rdtop 4 a a a a a TI F. - av - - - ° III“, 0 = a a (:7 a a ' a 50 AAMMJJJJAASIOONND 1 1 1 1 1 1 1 1 18181818181818181 date 1988 18-30 cm density (x500) - ---- --- ===== Gaga-g a a are- _ aaaaaaaaaaaa AAouJJJAAssoouuo 11111111 18181818181818181 date Figure 47. Mean seasonal densities of Metanzensmetus under different grasses at each depth during 1986. 112 KW Mesostigmata ranked second among Acarina, after Prostigmata; their relative dominance was 26.9% and 8.9% of total mites in 1985 and 1986 respectively. Two species of the mesostigmatids occurred regularly throughout this study: W W Willmann with 79.1% and 76.6% in 1985 and 1986, and fiypgaspig agglgifg; Canestrini with 7.0% and 6.8% dominance. All other species together constituted 13.9% of total Mesostigmata in 1985 and 16.6% in 1986 (Table 21 and Figure 48). All species recorded in this study are free-living and soil-inhabiting mites except for Dgzmgnygsus gelling; Degeer which is known to be ectoparasitic on birds and mammals. However, it has been stated by Gilyarov (1977) that its accidental appearance in soil is possible, The species made up only 2% of total mesostigmatids in 1985 and 3.3% in 1986. The mites probably dropped off birds and mammals visiting the study area. F.l. " 0‘ - 2?‘ 0 ‘I_ 0: :-u3‘ ‘ 0' {909: s ‘ _f Highly significant differences existed among grasses (p <0.001) in accommodating W 51135135115 populations in both years. Lumped over both depths, highest density in 1985 was found ‘under smooth. bromegrass with $150/m2 followed by orchardgrass with 4600/m2. Least numbers 113 Table 21. Relative dominance of species of order Mesostigmata in 1985 and 1986. 1985 1986 species N % N % 3. silesiagus 1326 79.1 911 76 6 a. aguiifer 113 7.0 81 6 8 0- selling: 34 2.0 39 3.3 other species 198 11.9 158 13 3 total 1676 1189 N = the total number of specimens obtained per year. 4. 1 1. .omaa.o:s mama :« suseofiunomez no mmaowem omuoeumm uo Auv mocncwEOG 0>Hus~0m .we endows Z ©w9 mm? 6:33 . 535% 2 EQQOQAI at mammogf MISSED 6.“ wasted, @3939:qu mamgcmEqu «.2 mo_oooam49:o 3.0on 550 o . QR d - ON msomummtm maofimmtm mbtmtmomooct mstoumombocm mofimow EmEmzmomoE 115 Table 22: population densities :SE/mz of Bhedasarsllus silgsiagus in each soil stratum under different grasses. n 1985 1986 0 - 15 cm 16 - 30 cm 0 - 15 cm 16 - 30 cm Grasses Mean SE Mean SE Mean SE Mean SE ejii pitE====a=fl_=====_,_====._====.____======= Sm. bg 2100 i500 3050 11000 1050 $350 1000 i450 Ky. bg 900 i350 1500 i450 1200 $300 1000 :250 Ordgrs 1750 i400 2850 $800 1650 1500 1150 £300 Timthy 600 £200 350 $100 750 :150 550 :150 T1 Fse 400 £150 50 150 200 £100 200 :50 Redtop 100 £50 100 :50 100 150 100 :50 N - 48 for 116 Rhodacarellus slleslacus 1985 Density 3800 5 - 0-1I on 30001“ """" 18-30 cm 2500 .+ ....... 2000 -’ 1800 a i 1000‘“ ........... m - I... o .1 8m. 8. K. B. 0:011. 1111:. T. F. Hdtp Grass Species 1986 Density 2000 a - 0-1I cm 18-30 cm 1800 -“ 1000 -‘ ’ 800 a " o- , . M 8m. 8. K. B. Oren. Tim. 1’. F. fidtp Grass Species Figure 49. Engggggggllgs silggiaggg densities /m2 in both soil~ strata under different grass covers. 117 were recorded for redtop with 200/m2. In 1986, orchardgrass, Kentucky bluegrass and smooth bromegrass all harbored large populations, while the lowest numbers again occurred under redtop with 200/m2 (Table 22 and Figure 49). Between - year numerical relationships were thus relatively stable. F.2- W: The species underwent large-scale numerical fluctuations during both years. In 1985 (Figure 50) densities peaked in October and November, but were low earlier in season. By contrast, highest abundances occurred in..April and. May in 1986 (Figure 51), followed. by low densities during the remainder of the year. Much as in n. W, and equally difficult to explain without knowledge of the species' biological characteristics, seasonal density patterns of 3 111351393: were thus very dissimilar from year to year. It is possible that the 1985 drought delayed reproduction of both species until the fall, and that the resulting population increase carried over into the spring of 1986. F.3 V‘ ' a q '9- 0| 0’ 19's: Only for 1986 could a significant effect of depth be shown for the species. In the first half of the 1985 season, 3. gilgsiaggs were more numerous in the upper stratum, while 118 Table 23: Mean seasonal density /m3 :83 of gilesiagus in upper and lower soil strata; data from all grasses lumped. 1985 1986 0 - 15 cm 16 - 30 cm 0 - 15 cm 16 - 30 cm Dates Mean SE Mean SE Mean SE Mean SE Aprl 1 --- --- --- --- 1750 i450 3650 $1300 Aprl 15 650 £300 300 1150 2800 $800 2150 1600 May 1 1800 £900 600 i250 3100 $1200 850 1400 May 15 900 :250 400 1200 1400 £750 250 i100 June 1 300 £200 50 i 50 400 :250 400 i300 June 15 1700 £900 600 :250 600 £300 50 150 July 1 900 :250 600 £200 400 £200 50 :50 July 15 900 £450 400 $150 350 $200 100 150 Aug 1 1200 $500 1200 £500 600 £150 200 :50 Aug 15 600 £450 900 £400 800 £200 250 1100 Sept 1 550 $450 400 £150 400 :250 200 :150 Sept 15 950 1750 450 £200 600 $300 250 1350 Oct 1 2100 i700 2600 11250 150 $100 150 1100 Oct 15 800 2200 4650 $2600 100 £50 450 3350 Nov 1 550 $200 4000 11950 350 1200 300 1100 Nov 15 600 $200 1850 $550 200 £100 300 1300 Dec 1 1250 i750 2100 $600 50 :50 400 :150 N = 18 perIdgte and dept;l 119 Rhodacarell US 51119517 acus 1985 density (Thousands) 6 ollllllllilllgng AAMMJJJJAASSOONND 1 l 1 l l 1 l l 15151515151515151 date Figure 50. Biweekly fluctuation of Bhodaggzgllns‘silesiagns during 1985, all grasses combined. 120 Rhodacarel! US 511951 acas 1986 density (Thousands) 6 ....................................... 3 ................................................................................. 2... ............................................................................................................... 1.. ................ 01114-11111111111 AAMMJJJJAASSOONND 1 l 111 l l 1 15151515151515151 date Figure 51. Biweekly fluctuation of Bhodagargllns 3113513933 ' during 1986, all grasses combined. 121 madman swam 1985 deuiiy (Items) NNNNK NNNN ‘ NN NVNN -0-IIII EDI-III- D I. Mil I ... 01.. o I. .II‘ I I. All A II Jlo' DO II .1... l- ..I “1‘ u .1 An... A I 1986 density (tunnel) -e-Isn EDI-III. 1““““‘§‘§§““§§ q 3 1‘ ~ I 1‘1‘~‘t s ““.“K .‘g a “ “\1‘~| u‘~“~\““““ II o D I. '1‘ I ... 0.1. 0 II .18. I I. ‘1‘ A ..I ...-II. J ... J18 ..- .1 “In. I ... AI.‘ A ... Vertical distribution of Bhodaggrgllns silgsiggng during 1985 and 1986, all grasses combined. Figure 52. 122 the opposite was true in October and November (Table 23 and Figure 53). Throughout most 1986 dates, however, the species clearly preferred the upper layer (Figure 52). To some degree edaphic variables can be used to explain differences in vertical distribution. Population density in the lower stratum in 1985 was positively correlated to soil moisture, and negatively to temperature. The negative density / temperature relationship was confirmed with 1986 data, indicating some sensitivity of the species to high temperature and low moisture. Single data tests of mean numbers of B. W under each turf grass showed significant differences between grasses on several dates and at both depths. In general (Figures 53 and 54), smooth bromegrass, Kentucky bluegrass and orchardgrass were the three species which harbored larger populations than any of the other three. F-4- WW1: Grass species differed. considerably in ‘terms of .H- agulifie; populations associated with them (p <0.001) in both years. Tall fescue *was clearly' the leader, followed by redtop (Table 24 and Figure 55) . Under all other grasses, numbers of H. agglgifig; were insignificant. 123 Rhoacarellus silesiacus 1985 0-15 cm density (x500) 14 12 10 l C 4 2 0 A A U H J J J J A A 8 3 O O N N D 1 1 1 1 1 1 1 1 1 5 1 5 1 5 1 5 1 5 1 5 1 5 1 5 1 date 1985 16-30 cm density (X500) 50- ... so ~--‘°' E§§§ 20"” ---------- .3231 9 “hp a a 3.;- 1'". ‘0‘. g . .‘t.:. on ' =="‘=. 1‘ a” KVDJ” o r I F r fr 1 I f I I i I 1 T r j?— “ b. A A H H J J J J A A 8 3 O O N N D 1 1 1 1 1 1 1 1 1 5 1 5 1 5 1 5 1 5 1 5 1 5 1 5 1 date Figure 53. Mean seasonal densities of Baggagargllns under different grasses at each depth during 1985. 124 Rhoacarellus silesiacus 1986 0-15 cm density (x500) 201 161‘." 104' :.-:- a a - 'ij . I a a, E's-‘5 T|$¢bp 1:1 213- o a: . was 2:: :2 ; : a - may :3: :f: :f: : . 3 a t =- . OM90 0 3: :1 i-S :65' :7 ‘ aaaaaEg/ ”:9 AAHMJJJJ A88 0 no 1 1 1 1 1 1 1 1 15151515151515151 date 1986 16-30 cm density (x500) zo‘fiiéfy.”fz 1°‘L----a--- _;;T% — .: “up 2:; s \:\ ===m =4I’:4I‘_L QEL Q-4_u '/7I Tm 54332 .3 till—1:: ail—‘\ 11:12} 03"” $.aplfi? A_5:av=vfi =v m 'u a! as 0;,91?????57????==aug° AAMMJJJJAABSOONND 1 1 1 1 1 1 1 1 15151515151515151 date Figure 54. Mean seasonal densities of Bhodagazgllna under different grasses at each depth during 1986. 125 mm; 39313113: is a predator which feeds on mature and immature stages of small arthropods. Tall fescue has an extensive root system which penetrates deeply and may create spaces offering relatively free movement to a hunting species. Whether it also harbors large populations of potential prey such as Collembola would have to be clearified in more comprehensive studies. F.5 :‘w1-. ‘ - _, 'on .- 119-279 T a - - ‘- 909, : .,; Even under tall fescue, abundance of n. 5931131131 was relatively low, which is not. unusual for' an obligatory predator. Using data from all grasses per date, a. agglgifig; abundance was found to fluctuate almost randomly in both years, with no distinct or repeated pattern (Figures 56 and 57) . v.5 WWI: Poplation densities differed significantly between depths (p <0.001). At virtually' all times, the species preferred the 0-15 cm stratum (Table 25 and Figure 58). Further studies would be necessary in order to correlate this preference with the distribution of pore space and potential prey. The latter is probably an important determinant of the predator's vertical distribution, since neither temperature nor moisture were related to H, agnlgifg; densities at either depth. Table 24: Population densities $SE/ma of Hingasnis aculifer in each soil stratum under different grasses. 1985 1986 0 - 15 cm 16 - 30 cm 0 - 15 cm 16 - 30 cm Grasses Mean SE Mean SE Mean SE Mean SE Sm. bg 0 -- O -- O -- o -- Ky. bg 100 :50 so -- so -- o -- Ordgrs 0 -- o -- o -- o -- Timthy 0 -- so -- so :50 o -- Tl Fse 850 1200 100 :50 400 :100 o -- Redtop 100 150 50 -- 250 :50 o -- N a 48 for 1985, 51 for 1986 127 Hypoaspis sou/eifer 1985 Denflty 1000 - - 0-16 cm 1o-ao om BOOs' 600" 400 - 3111.3. Ice. Oren. 11m. T.F. Rdtp Grass Species 1986 Danny 600 - - 0-16 cm 15-30 cm 400 - 300 -‘ 200-' 100- . 1 ........... o .11 8111.3. K.B. Oroh. Tim. T.F. Rdtp Grass Species Figure 55. _nypgggp13 agnlizg; densities /m2 in both soil strata - under different grass.covers. 128 Table 25: Mean seasonal density /m’ $SE of flypggfipig aculifier in upper and lower soil strata: data from all grasses lumped. 1985 1986 O - 15 cm 16 - 30 cm 0 - 15 cm 16 - 30 cm Dates Mean SE Mean SE Mean SE Mean SE Aprl 1 --- --- --- --- 200 £100 50 :50 Aprl 15 50 :50 50 $50 100 150 50 :50 May 1 100 :50 50 150 50 :50 O ,-- May 15 50 £50 50 :50 O -- 0 -- June 1 50 :50 O -- 100 :50 O -- June 15 300 £150 50 :50 50 :50 0 -- July 1 0 -- 50 :50 0 -- 0 -- July 15 200 £150 50 :50 200 $100 0 -- Aug 1 o -- o '-- 200 :150 o -- Aug 15 200 1150 50 :50 400 1200 50 :50 Sept 1 400 1350 O -- 350 £150 0 -- Sept 15 50 150 50 :50 150 1100 O -- Oct 1 500 :250 50 :50 0 -- O -- Oct 15 400 2200 50 150 150 £100 0 -- Nov 1 200 1150 50 150 50 :50 O -- NOV 15 200 :150 100 150 0 -- 0 -- Dec 1 50 :50 50 150 150 £100 0 -- 129 Hypoaspis aculeifer 1985 density 600 150(1- ................................................ 400 300 .. ......................................... 71 _ ........... A ........ : ............................. ft; v V (IN-‘9. r- aid) 1— 0.. m r- 1 date Figure 56. Biweekly fluctuation of fixpgagpis agnlifg; during 1985,. all grasses combined. 130 H ypoaspis aculeiter 1986 density 500 400- ............ . K ................................... , ........ . ....... 30C) .......................................... a: 200 ................................. 100 011 114111 AAMMJJJJAAS l 1 1 l 1 15151515151 date Figure 57. Biweekly fluctuation of Hypggfipis agulifgr during 1986, all grasses combined. 130 H ypoaspis aculeifer 1986 density 500 ‘40:)- ............................................... 300 200 100 0 l l _l L j l 1 l 1 l l l 1 5 1 5 1 5 1 5 1 5 date Figure 57. Biweekly fluctuation of Hypggfipifi agglifg: during 1986, all grasses combined. 131 Ermaamucruumbr 1986 density -I-I en SSH-8 en ‘5 "5“ . ... quest-u “ “‘ “\ “1 N \' ‘\ ‘k ‘\ 600 ”a d ....................-....... . u... .................. ........ d I II o...- o I. ' II A...- ‘ II J... Jul. 1.1 “I. I... an..-... A... 1986 density mil-l en -I-Icn ”0‘ " \ all Mil ' lo 0...! 0 i ‘ I. All 1....- Vertical distribution of 33393331: agnlifg: during 1985 and 1986, all grasses combined. Figure 58. 132 Grass-specific mean densities (Figures 59 and 60) differed on more than 30% of all dates in each year. As expected, tall fescue was invariably associated with the highest densities of H. agglgifig; on all occassions. 133 Hyp oaspis acuieifer 1985 0-15 cm density (x500) . .1 1 ......... 6-0". ._ ......... . ......................... ‘dr- ............................................... . .......... a-¥,#' ‘ 3 . :- 4=r a: a M159 2"- :zaaaaaa =7==7===7¢=I T'F. = a Tmthy 1 al- a ee 00 a e a a a e a ee 0 a 00 a e Odo. aazaaazaaaaaa“ =7: ”'9 0 I I I I I I I I I I I I I T I 8- .9 A H H J J J J A A 5 3 O O N N D 1 1 1 1 1 1 1 1 5 1 5 1 5 1 5 1 5 1 5 1 5 1 5 1 d3“! 1985 16-30 cm density (x500) 00. .‘ 0.1 0.. ° ........................ 0.. .............. 1 ....................... 00‘ _. a .. :7 a a =1» :_. . :7 0'2 .."'/V--a4_:=r-aaa-a¢_gi a. “It“, 0.1 " can-" gag-caa’fi; 5° ONO. aaazaaaaaaaaaaa W59 0 ’ T I I I r I I r f I I I I I r I I Sill b. A A M M J J J J A A 5 5 O O N N D 1 1 1 1 1 1 1 1 1 5 1 5 1 5 1 5 1 5 1 5 1 5 1 5 1 data Figure 59. Mean seasonal densities of 32293321; agglifg: under different grasses at each depth during 1985. 134 H ypoaspis aculeifer 1986 0-15 cm density (x500) ..... E H .ggL—a “up . E=a===a=.¢:‘ aaaeaae/ 01595 a =:=:=s=:=:=f=r=':='%r:=r=:='.=':=:=—/:=s.u§° AAUHJJJJAASSOONND 1 1 1 1 1 1 1 1 15151515151515151 date 1986 16-30 cm density (x500) 1 use ' 1 0.3 o: ",9,#‘ FL °-“ '_ _ - .11.:‘2192 ail-.222," Rates 0‘ " aaaaaaaaaaaaaaaaatnF. 00°. . -aaaaaaaaaaaagaga ONO. aaaaaaaaaaaaaaaa: Who 0 Sub: AAHMJJJJAASSOONMD 11111111 16161616161616161 date Figure 60. Mean seasonal densities of fiypgaspia agnlifez under different grasses at each depth during 1986. V. SUMMARY AND CONCLUSION The present study presents data on the distribution and abundance of selected taxa of Acarina obtained from soil samples taken from plots planted with six turfgrasses. Data were gathered for a two-year period (1985 and 1986), with samples taken at biweekly intervals from April to December of each year. Soil temperature and moisture were monitored concurrently. Acarina, more numerous than any other soil arthropods extracted from samples, were dominated by Prostigmata. Mesostigmata ranked second, while Cryptostigmata constituted less than 8% of all mites. Numbers of Astigmata were negligeable. Prostigmata have been shown to predominate in soils poor in organic matter. Soils in the study area were not particularly poor, but were certainly lower in organic matter than for instance, the A horizon of forest, where Cryptostigmata tend to dominate. Mite densities were generally much higher in the second year. In agreement with Mukharji et a1. (1970), this was probably due to increased rainfall and higher soil moisture. However, between-year discrepancies varied with taxon, 135 136 ranging from ‘very small differences in abundance (e.g. Eupodes spp.) to more than 20-fold increase in W spp. at the time of maximum population density. Seasonal abundance jpatterns observed in 1985 were usually repeated in 1986. Prostigmata as a group showed two main density maxima, in June - July and september - October. In 1986, the second of these peaks seemed to be due mainly to one of the constituent prostigmata genera, namely Igrggngmgg spp. Bakerdania spp.tended to be most numerous in April, while Eupodes, spp. increased dramatically in mid- season. W W provided an exception, in that the timing of population maxima differed between 1985 and 1986. Undoubtedly, some species thus reproduced at the same time each year, contributing to the synchronicety of population fluctuations. Others, prostigmatids as well as mesostigmatids, may have been either more flexible, or more dependent on suitable climatic conditions, resulting in irregular seasonal rhythms. Large fluctuations over time, as well as absence of a regular rhythm, have also been described by Dillon et a1. (1962). Clear preference for upper soil stratum, was exhibited by Eupodes spp. and the predaceous mesostigamtid flypgggpig W. In other taxa, soil moisture deficits in 1985 137 (particularly in the 16-30 cm stratum, to which rainfall did not. penetrate) contributed. to slight shifts in ‘vertical distribution. Although differences were not always significant, both downward movement in response to more evenly distributed moisture in 1986, and preference for the upper, relatively moister stratum in 1985, were observed. Migration of mites in reaction to moisture gradients has also been discussed by Sheals (1957) and Usher (1971). The latter author in particular concluded that Mesostigmata showed no distinct vertical stratification during periods of suitable climatic conditions. Several authors have commented on the difficulty of distinguishing the relative importance of the many factors anad interactions which determine population fluctuations of mites (Wallwork 1976; Sheals 1957; Dillon et al. 1962). In the present study, temperature and /or moisture were frequently correlated to seasonal abundance. These edaphic variables generally explained less than 30% of observed variation, and interpretaion must be cautious. In the case of ‘Egpggeg spp., for example, a positive relationship between temperature and abundance indicates that the animals were not adversely affected by high temperatures, but does imply a causative effect. In general, however, temperature and moisture were shown to 138 contribute significantly to seasonal as well as year-to-year differences in density. With regard to the central question, i.e., the potential effect of grass species on mite populations, there is almost no published work to draw on. Alejnikova et a1. (1975) found that different plant covers greatly affected the structure of soil animal populations. More pertinent, Christen (1974) concluded that pasture crops with dense root systems supported the largest populations of soil arthropods. The present study, given that soil type, climate, etc... were the same for all turf blocks, does not allow some general conclusions with respect to turfgrass effects. For several mite taxa, smooth bromegrass, Kentucky bluegrass and orchardgrass led in terms of supporting highest populations. Tall fescue was preferred by W agnlgifez, and redtop by Tygegg bedfordiensis in both years. The first three of these grasses have extensive root systems which may promote fungal and bacterial colonies on which microbial feeders could thrive. W spp. and Bakerdania spp. fall in this category (Kethley 1982). Interpretaion becomes tenuous in cases where yearly abundance shifted between grasses: this occurred in two taxa 139 for which feeding preferences are not known, Eupodes spp. and W W. Apparently, interactions between climatic factors, root development and the mites' food sources allowed them to be more flexible in terms of population growth under different grasses. Annual versus perennial root systems surely result in differing patterns of seasonal root distribution, turnover and decay. Redtop with its annual roots promoted populations of Iyggug bedfordiensis, a probable fungivore (Kethley 1982): a postulated system-specific fungal flora, differing. from that under other grasses, may explain the tight link between this mite species and redtop. The present study must be considered a pilot effort, aimed at a single faunal complement (Acarina). 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