llllIlIlI I 145 868 _THS_ GENETIC VARIATION IN RESISTAI‘ICE 0F SCOTCH PINE TO THE EASTERN PINESHOOT BDRER Thesis for the Degree of M. S. MICHIGAN STATE UNIVERSITY KIM CARLYLE STEINER 1971 RY I “1&3”; Stan: ~ Umvunty LIERA 1“; 1n1’“ amoms BY ‘5' ' ‘ HIIAG 8: SUNS' BUUK BINDEIIY INC . Llentnv BINDEFS | ”mug: .._:Y_,‘"f!| cm ABSTRACT GENETIC VARIATION IN RESISTANCE OF SCOTCH PINE TO THE EASTERN PINESHOOT BORER BY Kim C. Steiner Larvae of the Eucosma gloriola moth kill young twigs on Scotch pine, causing unsightly damage. To determine if some varieties of this tree are genetically resistant to Eucosma, attack was measured on 110 seedlots of Scotch pine belonging to 19 varieties. The trees were planted at three locations in southern Michigan: Allegan County (70 seedlots), Shiawassee County (76 seedlots), and Kalamazoo County (106 seedlots). Each plantation was measured in either one or two different years. Most results were consistent from plantation to plantation and year to year. There were highly significant differences in attack among seedlots in all plantations and years, indicating that there are genetic differences in resistance. Most of the variation was due to differences among varieties. At the most heavily-attacked plantation, the short northern varieties had from 1 to 4 attacks per tree, the tall central Kim C. Steiner European varieties had from 2 to 6 attacks per tree, and the medium-height southern and western varieties had from 6 to 10 attacks per tree. Some variation was due to differences among seedlots within varieties, but no seedlots were significantly better or worse than their varietal means at every plantation. Of the characters studied in searching for a possible mechanism of resistance, winter foliage color was most highly correlated with resistance. Yellow varieties were least-attacked and green varieties were most-attacked. Height, mineral nutrients, and resistance patterns to other insects were not related with susceptibility to attack. There was a very limited correlation between two cortical monoterpenes and resistance to eucosma. The varieties which are most preferred for Christmas tree planting are also most susceptible to eucosma, but variety aquitana was the least-attacked member of this group. GENETIC VARIATION IN RESISTANCE OF SCOTCH PINE TO THE EASTERN PINESHOOT BORER BY Kim Carlyle Steiner A THESIS submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Forestry 1971 ACKNOWLEDGMENTS I wish to extend my sincere gratitude to Dr. J. W. Wright. His guidance and patience were an invaluable aid to this study. I am also indebted to George Howe, Warren Nance, and Fred Hain for the use of certain data which they collected in 1968 and 1969. Finally, I wish to thank my wife, Susie, for the considerable time she spent typing the manuscript and aiding me in the collection of data. My financial support during the course of this study was provided by the National Science Foundation through its Graduate Traineeship Program. ii TABLE OF CONTENTS LIST OF TABLES. . . . . . . . . . . . . . . . . . LIST OF FIGURES . . . . . . . . . . . . . . . . . INTRODUCTION . . . . . . . . . . . . . . . . . . A BRIEF HISTORY . . . . . . . . . . . . . . THE TREE . . . . . . . . . . . . . . . . . . THE INSECT . . . . . . . . . . . . . . . . . OBJECTIVES . . . . . . . . . . . . . . . . . MATERIAL AND METHODS . . . . . . . . . . . . . . THE PLANTATIONS . . . . . . . . . . . . . . MEASUREMENT OF ATTACK . . . . . . . . . . . STATISTICAL ANALYSIS . . . . . . . . . . . . Analysis of Variance Analysis of Seedlot X Year Interaction Evaluation of Varietal Differences GENETIC DIFFERENCES IN RESISTANCE . . . . . . . . DIFFERENCES WITHIN AND AMONG VARIETIES . . . CONSISTENCY IN THE RESULTS . . . . . . . . . POSSIBLE MECHANISMS OF RESISTANCE . . . . . . . . GENEML MECHANISMS C O O O O O I O C O O O O DISTINCTIVE FEATURES OF RESISTANT AND SUSCEPTIBLE VARIETIES . . . . . . . . . iii 10 11 ll 14 15 18 18 25 35 35 37 Height Color Mineral Nutrients Monoterpenes COMPARISON WITH RESISTANCE PRACTICAL APPLICATION SUMMARY LIST OF REFERENCES APPENDIX INSECTS iv PATTERNS TO 43 45 47 49 53 TABLE 1. Al. LIST OF TABLES Page Varietal differences in number of eucosma attacks per tree at each of three plantations in 1970 . . . . . . . . . 19 Analyses of variance for number of eucosma attacks per tree at each of three plantations in 1970 . . . . . . . . . 20 Percentage of trees attacked by eucosma in each variety in all plantations and years 0 O O O O O I O I O O O O O O O I O O 21 Analyses of variance for percentage of trees attacked by eucosma at each of three plantations in different years . . . 22 Analyses of variance for percentage of trees attacked by eucosma combined over two years at each of two plantations . . . 27 Varietal differences in percentage of trees attacked by eucosma averaged for three plantations in years of moderate infestation, with 1971 relative height averaged for four plantations . . . . . . . 29 Varietal differences in susceptibility to attack by five insect pests, as reported by Wright et a1. (1966) and Wright and Wilson (1971) . . . . . . . . . 44 Varietal differences in percentage of trees attacked by eucosma at Allegan and Rose Lake in 1970, a year of heavy infestation at those plantations . . . . . 53 TABLE A2. A3. Page Number of attacks by eucosma in each seedlot at all plantations in 1970, and average color grade of each seedlot at Allegan in 1970 . . . . . . . . . . . . 54 Number of trees attacked by eucosma in each seedlot at all plantations and in all years . . . . . . . . . . . . . . . . 58 vi FIGURE 1. LIST OF FIGURES Page Relation between percentage of trees attacked by eucosma and number of attacks per plot. 0 O O O O I O O O O O O O O O I O 31 Relation between percentage of trees attacked by eucosma and winter foliage calor O O O O O O O O O O O O O O O O O O O 39 vii INTRODUCTION In Michigan and other northeastern states, Scotch pine is one of the most common ornamental and Christmas trees. Its short, blue-green foliage and its excellent adaptability are two of the many features of this tree species which make it popular. Unfortunately, however, it is afflicted with sev- eral damaging insect pests. One of these insects is the eastern pineshoot borer (Eucosma gZorioZa Heinrich). Although a plant species may be characterized as being susceptible to an insect pest, it is sometimes possible to find individuals of that species which are inherently resis- tant. These resistant individuals can be bred, if desired, to produce a strain that is not subject to damage by the insect. However, if the plants that are resistant come from a certain part of the species range, one need only collect seed there to get plants which are less susceptible to insect damage. This study was intended to explore the pos- siblity that some of the Scotch pine varieties are inher- ently resistant to Eucosma. Known examples of genetic dif- ferences within plant species in resistance to insects are common in crop plants, but they are relatively rare in forest trees. A BRIEF HISTORY The study of insect resistance in plants is quite old. As early as 1831 one apple variety was known to be more resis- tant than other varieties to the woolly apple aphid, Eriosoma Zanigerum (Hausm.). Later in the 19th century several var- ieties of winter wheat were found to be resistant to the Hessian fly, Mayetiola destructor (Say). But not until the early part of this century were concentrated efforts begun in breeding for resistance. These studies were mainly on economically important food plants and their more destruc- tive pests. In his classic book, Painter (1951) reviewed these early studies and described the theory and application of breeding for insect resistance in crop plants. Although research in agriculture preceded that in for- estry, several possible cases of genetic insect resistance in forest tree species have been reported. Unfortunately, most of these studies do not present conclusive evidence because they suffered from a lack of replication. Some of the research was fairly early. Hall (1942) reported that he thought several races of black locust (Robin- ia pseudoacacia) were resistant to the locust borer (Megacyl- Zane robiniae). Austin et a1. (1945) felt that they had found possible resistance to the resin midge (Retinodiplosis sp.) in ponderosa pine (Pinus ponderosa). Those trees with glau- cous or glabrous shoots were less attacked than those with viscid shoots. Miller (1950) reported that the backcross hybrid {Pinus jeffreyi x (P. jeffreyi x P. coulteri)} was resistant to the pine reproduction weevil (Cylindrocopturus eatoni). This insect is a serious pest on Jeffrey pine, and a large-scale breeding program based on his results has been initiated (Libby, 1958). I Good evidence of insect resistance in forest trees was shOwn in a repliCated test by Schreiner (1949). He found dif- ferences among full-sib clones of poplar (PopuZus sp.) seed- lings in resistance to the Japanese beetle (PopiZZia japonica). Among the second-generation hybrid progeny of the same two species, some clones suffered no attack and others 100% attack. His paper is the earliest statistically adequate proof of genetic variability in insect resistance in forest trees. Two recent studies in forestry show good statistical evi- dence of intraspecific differences in genetic resistance. Batzer (1962) demonstrated in a well-replicated experiment in Minnesota that some origins of jack pine (Pinus banksiana) were more susceptible than others to white pine weevil (Pissodes ‘ strobi). Wright et a1. (1966 and 1967) studied European pine sawfly (Neodiprion sertifer) on Scotch pine at four replicated plantations in Michigan. In general, the resistance of a var- iety was correlated with its growth rate; the tallest varie- ties were attacked most. However, variety uraZensis was much more resistant than expected for its height. They found that larval development was slower on that variety than on others. They also found possible differences in resistance to three other insects: white pine weevil, jack pine budworm, and pine webworm. For a more complete review of the lit- erature on insect resistance in forest trees, see Gerhold et al. (1966). THE TREE Scotch pine (Pinus sylvestris L.) is the most widely distributed conifer in the world. It is also one of the most genetically variable forest trees. In northern Europe, where it is native, Scotch pine is the most important commercial timber species. In the United States, where it has been introduced, it is our most important plantation Christmas tree. Its importance and variability have led to considerable study of insect resistance in Scotch pine. Much of the research has been in comparing this and other species in rela- tive resistance to certain insects. Information on such differences is valuable in determining which species to plant on a site. Other research has been in investigating the possibilities of intraspecific differences in resistance to insects. Scotch pine has been compared to other pines in rela- tive susceptibility to European pine shoot moth (Rhyacionia bquiana) by Neugebauer (1952), Miller and Heikkenen (1959), Harris (1960), Haynes and Butcher (1962), Holst (1963), and Schonborn (1966). Bennett (1954) demonstrated that Scotch pine is more resistant to Exoteleia pinifolieZZa than lodge- pole pine (Pinus contorta) or jack pine, possibly due to its larger number of resin canals. In an early study involving Rhyacionia frustrana, Graham and Baumhofer (1930) reported Scotch pine to be one of the most resistant of the five pines studied. These authors were ahead of their time in char- acterizing resistance as genetic variation in two factors -- preference for oviposition and ability to recover after attack. Several possible examples of intraspecific differences in resistance have been cited for Scotch pine. In one of the earliest studies, MacAloney and Johnston (1933) repOrted that the "Riga strain" appeared to be most resistant to the white pine weevil; however, their report has not been substanti- ated by later studies. Rudolf and Patton (1966) also report- ed apparent genetic differences in resistance of Scotch pine to this insect. Vofite (1940) observed that adults of Pissodes piniphi- Zus seemed to prefer certain individual trees for oviposition. These trees were not diseased or weakened, and no other rea- son could be found for this preference. Skuhravy and Hochmut (1969) reported that certain geographic origins of Scotch pine were attacked more than others by Thecodiplosis brachyn— tera. In the only replicated experiment to date, Wright et a1. (1966 and 1967) found that resistance to European pine saw— fly differed significantly among varieties of Scotch pine at four plantations. In smaller experiments they also found significant differences among varieties in attack by three other insects. THE INSECT The eastern pineshoot borer (Eucosma gZorioZa Heinrich, Lepidoptera, Olethreutidae), commonly called eucosma, is a pest of Scotch pine. This insect occurs east of the Rocky Mountains in Canada and the northern United States. In addition to Scotch pine, it has been reported to attack eastern white pine (Pinus strobus), red pine (P. resinosa), Austrian pine (P. nigra), pitch pine (P. rigida), jack pine, mugho pine (P. mugho), Norway spruce (Picea abies) and Douglas-fir (Pseudotsuga menziesii). However, its favorite hosts are eastern white pine and Scotch pine (Drooz, 1960). Adults of eucosma are coppery-red moths with wing spans of about one-half inch. In late April or early May the females deposit their eggs on the needle sheaths of the trees' new growth. After a period of two to four weeks the larvae hatch and bore directly into the twigs. Usually only one larva per brood will survive to reach the pith of the twig. Once inside it mines up and down the pith from just above the node to near the tip. The larvae become 1/2 to 1 inch in length. They feed until July when they bore exit holes, drop to the ground, and pupate. The damage to the trees occurs when the larvae gir- dle the stems from the inside shortly before exiting. This is considered to be an adaptive mechanism that prevents the insects from becoming entrapped in pitch as they leave the shoots. The attacked shoots die by late summer. For a more complete description of the insect and its damage, see Drooz ‘(1960) and Newman (1968). Damage caused by E. gZorioZa is similar to that of Rhy- acionia frustrana, the Nantucket pine tip moth. Drooz (1960) stated that the importance of E. gZorioZa has gone unrecog- nized because of its confusion in the past with this other, better-known species. Another similar species is Eucosma sonomana Kearfott. The life history of this insect is the same as that of E. gZorioZa. In fact, Heinrich, (1931) in his original des- cription of E. gloriola, stated that it may be a race of E. sonomana. The hosts of these two species are similar; how— ever, the latter has also been reported on ponderosa pine and _ Engelmann spruce (Picea engeZmannii). DeBoo (1967) examined specimens referred to as E. sonomana on jack pine in Minne- sota and concluded that the insect was actually E. gZorioZa and that E. sonomana is restricted to the western states where ponderosa pine grows. According to Butcher and Hodson (1949), damage from E. sonomana has also been often attribu- ted to Rhyacionia frustrana. Damage from Eucosma sp. is sometimes important. Drooz (1960) reported that high incidence of leader attack by E. gZorioZa on Scotch pine is a serious problem to Christmas tree growers. Butcher and Hodson (1949) and Shenefelt and- Benjamin (1955) observed, respectively, up to 70% and 90% of the leaders on jack pine to be destroyed by E. sonomana (or E. gZorioZa). Repeated attacks reduced growth and resulted in a bushy appearance characterized by the absence of a dominant leader. Genetic studies on resistance to either E. gloriola or E. sonomana are inconclusive and have been performed only on jack pine. In a study of eight geographic origins in a 9- year old plantation of this tree Species, Butcher and Hodson (1949) reported possible differences in susceptibility to E. sonomana (or E. gZorioZa). However, they were cautious in attaching significance to the results since diversity with respect to site and age had not been considered in the ana- lysis. These results were contradicted by those of Schantz- Hansen and Jensen (1952) from a study done on jack pine in the same area (in Minnesota). They found no relation between source of seed and the amount of infestation. In their ana- lysis, they included 32 origins, from New Brunswick and Maine to Alberta and Minnesota. More recently, King (1971) reported a study of E. gZorioZa attack on 11 replicated plantations of jack pine in Minnesota, Wisconsin, and Michigan. The plantations inclu- ~ded 26 geographic origins from these three states. None of the 8 plantations which were attacked five years after plant- ing showed significant differences among seed sources in amount of attack. However, three of the four plantations which were heavily attacked 10 years after planting showed significant differences among seed sources. Seed source x plantation interaction was also significant. Most of the variation was explained by a negative correlation between attack incidence and 10-year height. 10 OBJECTIVES The principal objective of the present study was to determine if there are genetic differences among varieties and among seedlots (seed sources) within varieties of Scotch pine in resistance to attack by Eucosma gloriolu. A second- ary objective was to determine the possible mechanism of resistance by attempting to correlate attack with other gene- tically-controlled and variable characteristics of this tree species. MATERIAL AND METHODS THE PLANTATIONS In 1961, Michigan Agricultural Experiment Station, in cooperation with other states, established several plantations of Scotch pine as part of the NC-Sl range-wide provenance test of this species. These plantations were established with 2-0 seedlings grown from seed obtained in 110 native stands of Scotch pine, although every stand is not necessarily repre- sented in each plantation. In the present study the offspring of a single stand are referred to as a seedlot. These 110 seedlots represent the entire range of this species in Europe and Asia. The plantations are arranged in a randomized complete block design, with an 8 x 8 foot spacing between trees. Each seedlot is represented once in each block by a 4-tree plot. Further details of the history and design of these plantations can be found in Wright and Bull (1963). This experiment has been the basis of many studies on Scotch pine. Wright and Bull (1963) studied geographic var- iation on the basis of seedling performance. Steinbeck (1965) examined trees in some of the plantations for differ— ences among the seedlots in foliar mineral accumulation. Wright et a1. (1966) analyzed variation in mortality, growth 11 12 rate, winter color, needle length, winter injury, flower pro- duction, and susceptibility to four insects at 31 plantations in eight north-central states. Ruby (1964) used the material for part of his work on the taxonomy of Scotch pine. He rec- ognized 21 varieties of this species. Wright et a1. (1967) detected differences among the varieties in resistance to EurOpean pine sawfly. Tobolski (1968) used the plantations for part of his study on the variation in monoterpene compo- sition among varieties and half-sib families of Scotch pine. The location and size of the three plantations used in my study are given in the following tabulation. Further descriptions are contained in the succeeding paragraphs. North West No. of No. of Plantation County Lat. Long. Seedlots Blocks 0 o Allegan Allegan 42.5 86.0 70 10 Rose Lake Shiawassee 42.8 84.3 76 7 Kellogg Kalamazoo 42.3 85.3 106 6 Allegan Recreation Area is located near the town of Allegan, Michigan. The Scotch pine plantation here was nearly perfect for this study.. The trees were well-formed, mortal- ity had been negligible, and damage from winter injury and other insects was very slight. The plantation occupies a level site and is well-separated from other tall trees. Average height was the lowest of any plantation, probably due 13 to the sandy, infertile soil. The canopy was still open at the time of this study. Eucosma infestation was heavy in 1970. Rose Lake Wildlife Experiment Station is located 10 miles northeast of Michigan State University, East Lansing, Michigan. The Scotch pine plantation, located on a gentle slope, is bordered by a gravel road, a small grassy field, a hedge of multiflora rose, and a tall Scotch pine windbreak. Some trees were more than 20 feet tall at the time of this study, and the canopy was beginning to close. Eucosma infestation was heavy in 1970. W. K. Kellogg Experimental Forest is located 15 miles from Battle Creek, Michigan. The site is rolling, and the Scotch pine plantation occupies the middle and both sides of a large draw. In places the slope is as much as 30%. This plantation is surrounded by other plantations, but it is separated from them by fire lanes. Many trees exceeded 20 feet in height at the time of this study, and the can0py was beginning to close. Some slower-growing seedlots were less than knee height, but this was true at all plantations. Eucosma infestation was light at this plantation in 1970. l4 MEASUREMENT OF ATTACK As early as 1968, Eucosma gloriola began to invade these plantations. In the autumn of that year, George Howe and Warren Nance, graduate students at Michigan State University, counted the number of trees attacked in each plot at Allegan. In the autumn of 1969, Fred Hain, another graduate student, counted the number of trees attacked by this insect at Rose Lake. This was the situation when, at the suggestion of Dr. J. W. Wright, I elected to look for possible variation in resistance to this insect. In the autumn of 1970, I counted the number of trees attacked at the Kellogg plantation and made new counts at the Allegan and Rose Lake plantations. Measurements were also made of the total number of attacks in each plot (4 trees). The measurements to be statistically analyzed comprised eight sets of data: the number of attacks per plot at Allegan (1970), Rose Lake (1970), and Kellogg (1970); and the number of trees attacked per plot at Allegan (1968), Allegan (1970), Rose Lake (1969), Rose Lake (1970), and Kellogg (1970). 15 STATISTICAL ANALYSIS Analysis of Variance An analysis of variance was performed on each of the 8 sets of data using the plot totals as items. When there were one or two trees dead on a plot, the plot totals were adjusted to a 4-tree basis. If there were more than two trees dead on a plot, that plot was not considered in the analysis. For missing plots I substituted the seedlot mean, and subtracted an appropriate number of degrees of freedom from the error term. The total variation in attack for each set of data was separated into the variances due to blocks, error, and seed- lots. The seedlot variance was then separated into that due to variety differences (using varieties recognized by Ruby, 1964) and that due to seedlot-within-variety differences. In order to determine the levels of significance, the seed- lot-within-variety variance term was tested against the error variance of seedlots within varieties. Analysis of Seedlot X Year Interaction Seedlot x year interaction is an estimate of the dif- ferences between years in the relative incidence of attack among seedlots in the same plantation. I calculated the 1968 versus 1970 interaction for Allegan and the 1969 versus 1970 interaction for Rose Lake, using data on percentage of 16 trees attacked. The interaction variance term for each plant- ation was tested over its pooled error variance to determine significance. There was one important problem associated with testing the seedlot x year interaction terms. At each plantation the error variances for the two years were unequal. Cochran and Cox (1957) give a conservative procedure to follow in such cases. I applied both their procedure and the normal procedure to the analyses and obtained the same significance levels. Evaluation of Varietal Differences Number of attacks per tree. To determine the signifi— cance of individual varietal differences for these data, I used the Student-Newman-Keuls least significant range pro— cedure (Sokal and Rohlf, 1969), which is one of the more con- servative multiple range tests. I applied the test separately to the data for each plantation. In this method the signi- ficance of the difference between two varieties is based upon their distance apart in rank, their sample sizes, and the error variance. Because the varieties often had unequal sample sizes, it was necessary to employ weighted averages. Number of trees attackedgper plot. To analyze these data, I chose to use one of the tests for proportions which approximate the Chi-Square distribution. For this purpose 17 the data were converted into percentage of trees attacked in each variety. A preliminary test using the "chi-square" test of differ- ences showed that Allegan (1970) and Rose Lake (1970) were so ”highly attacked that very few differences could be found. For this reason these plantations were ignored for those years, and the results for the remaining plantations and years were combined to obtain an overall percentage of attack for each variety. These proportions were analyzed by the G-statistic of Sokal and Rohlf (1969). Each variety was compared to every other variety. A significant difference in this test is based upon the magnitude of difference between the observed proportion of trees attacked and the expected proportion. The expected proportion is calculated on the assumption that there exists no real difference between the varieties. GENETIC DIFFERENCES IN RESISTANCE DIFFERENCES WITHIN AND AMONG VARIETIES There were highly significant differences in attack among seedlots, indicating that there are genetic differences in resistance. This was true at all plantations and in all years (Tables 1 to 4). Most of the variation among seedlots was due to differences among varieties rather than differ- ences among seedlots within varieties -- as indicated by the smaller F-values of the latter. This tends to support Ruby's (1964) method of grouping the seedlots into varieties. Consequently, the differences within varieties were less consistent. At Rose Lake (1970) this variance term was significant for both number of attacks per tree and per- centage of trees attacked, and at Allegan (1970) it was sig- nificant for number of attacks per tree (Tables 2 and 4). But all other plantations and years did not show significant differences among seedlots within varieties. No particular seedlots departed significantly from the varietal averages in all plantations or in all years. Wright et a1. (1966) stated that the within-variety variation in the traits they measured was best considered to be geographically at random. 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Ioflfid IHHmM. mmom Imaad mafia mmocouwMMHU mo mxowuum umofiuma mmuu HomImxomuud nouoom mo wUGMOHM4cmHm mxompum umm3mmu4 muofium> 444m .4o>o4 4m 04» pm usouowmao >4u:404M4smHm mum Hmuyo4 0844 may mcfluMSm no: mmflumflum> .0444 :4 mcoaumuc44m omnnu mo £040 um ooh» mom mxomuum mEmooso mo Honfisc :4 moocouwMMHo 4mumwum>ll.4 04449 20 Table 2.--Analyses of variance for number of eucosma attacks per tree at each of three plantations in 1970. Seedlot Plantation within and year Block Variety variety Error Degrees of Freedom Allegan (1970) 9 16 53 603 Rose Lake (1970) 6 19 56 419 Kellogg (1970) 5 19 86 508 Mean Squares Allegan (1970) 229.5522a 820.2825 122.7362 35.0977 Rose Lake (1970) 1551.1550 Kellogg (1970) 13.8080 Allegan (1970) 6.54*** Rose Lake (1970) 9.27*** Kellogg (1970) 2.37* 2581.9478 226.6273 167.3841 54.9373 6.2298 5.8371 F - Values 6.68*** 3.50*** - - 11.39*** 1.35* - - 8.82*** 1.07 - - a) Analyses were computed using 4-tree plot totals. Divide mean squares by 16 to convert to a per-tree basis. *, ***) Indicates significance at the 5 and 0.1% levels, respectively. 21 Table 3.--Percentage of trees attacked by eucosma in each variety in all plantations and years. Variety Percent of trees attacked at of Scotch I Weighted . Allegan Rose Lake Kellogg Plne 1968 1970 1969 1970 1970 average Scandinavian and Siberian Varieties lapponica 2 49 25 79 5 24 mongolica -- 18 0 32 15 16 altaica ll 88 30 75 18 48 septentrionalis 15 94 25 80 22 50 rigensis 25 98 38 81 33 59 uralensis 14 98 24 73 15 48 Central European Varieties polonica 27 96 29 79 58 61 borussica 32 98 38 73 33 59 hercynica 37 95 42 82 47 63 haguenensis 40 94 37 76 38 59 'East Anglia' -- -- 32 75 38 46 pannonica 36 100 54 89 46 69 illyrica 25 100 46 86 63 67 West and South European Varieties 'North Italy' -- -— 58 92 54 69 scotica -- -- 36 100 43 52 iberica 52 98 61 94 59 75 aquitana 45 99 49 94 50 68 rhodopaea 52 99 49 95 56 72 armena 42 99 60 95 49 68 Plantation mean 32 93 40 83 39 59 22 Table 4.--Ana1yses of variance for percentage of trees attacked by eucosma at each of three plantations in different years. Seedlot Plantation within and year . Block Variety variety Error Degrees of Freedom Allegan (1968) 6 15 53 393 Allegan (1970) 9 16 53 605 Rose Lake (1969) 6 19 56 431 Rose Lake (1970) 6 19 56 419 Kellogg (1970) 5 19 86 508 Mean Squares Allegan (1968) 6.2750a 9.7500 1.4989 1.2143 Allegan (1970) .3911 10.6043 .3384 .2479 Rose Lake (1969) 34.7183 7.2179 1.2291 .9477 Rose Lake (1970) 8.5450 4.0463 1.1084 .6986 Kellogg (1970) 2.7220 12.0742 1.1331 1.1257 F - Values Allegan (1968) 5.17*** 6.50*** 1.23 - - Allegan (1970) 1.58 31.34*** 1.36 - - Rose Lake (1969) 36.63*** 5.87*** 1.30 - - Rose Lake (1970) 12.23*** 3.65*** 1.59** - - Kellogg (1970) 2.42* 10.66*** 1.01 - - a) Analyses were computed using numbers of trees attacked per plot. *, **, ***) Indicates significance at the 5, l, and 0.1% levels, respectively. 23 resistance to eucosma attack, also. In any particular var- iety, northern seedlots performed the same, on the average, as southern seedlots. However, considering the means of all varieties, there was a noticeable north to south trend in number of attacks per tree (Table 1). Northern varieties were attacked least and southern varieties were attacked most. This is in agreement with the results of studies on other genetically variable traits in Scotch pine. Most characters which vary do so in a north to south manner (Wright and Bull, 1963). There was one striking departure from the latitudinal trend. This occurred at Allegan. The northern Asian var- iety uralensis had significantly more attacks per tree than some of the central European varieties. This was also true to a lesser extent for the northern European varieties septentrionalis and rigensis. Table 1 shows which varieties differed from one another in average number of attacks per tree. At Rose Lake all northern and central European varieties were not signifi- cantly different. The western European variety sootica was most highly attacked and tended to group with the southern European varieties. Of the southern varieties, rhodopaea, with the fewest attacks in this group, was most unlike the others. At Kellogg all varieties except for three were not significantly different. This was because of the overall low degree of infestation. Variety lapponica had significantly 24 fewer attacks per tree than varieties rhodopaea and iberica, but the latter were not significantly different from one another. Among the varieties which performed most consistently, mongolica and lapponica warrant special comment. At all plantations (Tables 1 and 3) these varieties were least attacked. This was probably because they are by far the shortest of all the varieties and offer only small targets for attack. This was especially true at Allegan, where occasional individuals in these varieties were less than one foot tall at age 11. 25 CONSISTENCY IN THE RESULTS In Tables 1 and 3 I list the number of attacks per tree and the percentage of trees attacked in each var- iety for all plantations and years. These tables show good consistency in the results from different plantations and years. Nevertheless, there were a few apparent var— iety x plantation interactions. Some can be explained as probable artifacts. For example, in Table 1 the unusually high (relative to other plantations) number of attacks on variety uralensis at Allegan is largely due to two exceptional plots. The other 18 plots in that var- iety were much less attacked. Several inconsistencies, however, cannot be explained in this manner. In Table 1, variety scotica had rela- tively many more attacks per tree at Rose Lake than at Kellogg; and variety iberica had relatively fewer attacks per tree at Allegan than at Rose Lake and Kellogg. In Table 3, variety polonica had a relatively larger percent- age of trees attacked at Kellogg than at Allegan (1968) and Rose Lake (1969); and variety illyrica had a rela- tively smaller percentage of trees attacked at Allegan (1968) than at Rose Lake (1969), and a relatively larger percentage of trees attacked at Kellogg than at Rose Lake (1969). The data offer no clues to the reasons for these apparent interactions. However, interaction of insect 26 resistance with site is not unusual. According to Painter (1951) edaphic factors can influence insect resistance in a plant. Thus, differences in the responses of varieties to an edaphic factor can indirectly affect their relative insect resistance. Two plantations were statistically analyzed for consistency in the results from different years (Table 5). Seedlot x year interaction was highly significant at Allegan (1968 and 1970), but not significant at Rose Lake (1969 and 1970). Inspection of Table 3 reveals the source of the inconsistency in results between years at Allegan. The interaction may be considered an artifact due to differences in insect population levels in dif- pferent years rather than differences in the relative resistance of some varieties. Many varieties which were significantly different in 1968 were virtually the same in 1970, causing the interaction term in Table 5 to be significant. The fact that differences among varieties in per- centage of trees attacked decreased under high levels of insect population does not necessarily mean there are no genetic differences in resistance. Insect resistance in plants usually exhibits continuous variation. It is rarely an absolute, all or none, character. Under high population levels the chances become proportionately smaller of a tree escaping attack entirely. 27 Table 5.--Ana1yses of variance for percentage of trees attacked by eucosma combined over two years at each of two plantations. principally due to varietal differences. Seedlot variation is Plantation Seedlot Pooled and year Year Seedlot x year error Degrees of Freedom Allegan (1968 l 69 69 998 and 1970) Rose Lake (1969 l 75 75 850 and 1970) Mean Squares Allegan (1968 1779.48a 4.2499 1.8662 .6458 and 1970) Rose Lake (1969 783.43 3.6385 .9604 .8232 and 1970) F - Values Allegan (1968 953.63*** 2.16** 2.89*** - - and 1970) Rose Lake (1969 816.07*** 3.79*** 1.17 - - and 1970) a) Analyses were computed using numbers of trees attacked per plot. **, ***) Indicates significance at the l and 0.1% levels, respectively. 28 Although high population levels can increase the abso- lute number of attacks per tree, the relative number of attacks per tree should not be affected if differences are due to genetic resistance. So it is that Allegan (1970) showed few differences in percentage of trees attacked (Table 3) but many in number of attacks per tree (Table 1). For example, haguenensis and septentrionalis both had 94% of their trees attacked at Allegan in 1970, but the former averaged 2.8 attacks per tree and the latter aver- aged 4.0 attacks per tree, a difference which is signifi- cant. The conclusion that there are genetic differences in resistance to eucosma is not weakened by the lack of differences in percentage of trees attacked at Allegan (1970). It is interesting to note that although the attack level was high at Allegan in 1970, there were a few indi— vidual trees that escaped attack entirely, even in the varieties which had many attacks per tree. This was emphasized in the field where I occasionally observed a single unattacked tree in an otherwise highly-attacked 4-tree plot. Almost all trees were attacked in years of heavy infestation. Therefore, to look at differences among varieties in percentage of trees attacked, I used only the data from years of moderate infestation: Allegan (1968), Rose Lake (1969), and Kellogg (1970). Table 6 29 Table 6.--Varietal differences in percentage of trees attacked by eucosma averaged for three planta- tions in years of moderate infestationh with 1971 relative height averaged for four planta- tionsz. Varieties not sharing the same letter are significantly different at the 5% level. Variety of Trees attacked Significance Relative height Scotch pine (% of total) of differences (% of mean)3 Scandinavian and Siberian Varieties lapponiea 7 a 55 mongolica 9 ab 93 altaiea 18 abc 76 septentrionalis 21 bcde 82 rigensis 31 cdef 96 uralensis 19 abcd 92 Central European Varieties polonica 37 fgh 112 borussica 34 defg 112 heroynica 42 fghij 119 haguenensis 38 fgh 124 'East Anglia' 36 efgh 111 pannonica 47 fghijk 114 illyrica 44 fghijk 110 West and South European Varieties 'North Italy' 56 jk 101 scotica 41 fghi 99 iberica 58 k 86 aquitana 49 ghijk 106 rhodopaea 53 ijk 104 armena 51 hijk 94 1) Allegan (1968), Rose Lake (1969), and Kellogg (1970). 2) Kellogg and three similar plantations in Cass, Newaygo, and Crawford counties in southern Michigan. 3) Mean height of the four plantations was 12.1 feet. 30 shows specifically which varieties differed significantly from one another at these combined plantations using the G-statistic of Sokal and Rohlf (1969). This made it possible to look at consistency in results between number of attacks per tree and percentage of trees attacked. In general the results presented in Table 6 agree well with those presented in Table 1. To be more certain of this consistency, I regressed mean number of attacks per plot (a function of mean number of attacks per tree) for those seedlots common to all plantations on the percentages of trees attacked in those seedlots at Allegan (1968), Rose Lake (1969), and Kellogg (1970): Source d£_ Mean Squares F Regression 1 584.11 47.72*** Residual 56 12.24 Total 57 ***) Indicates significance at the 0.1% level. The significance of the regression shows that the two mea- surements agreed well in their results (r = .68). In Figure 1, I have plotted mean number of attacks per tree and percentage of trees attacked for each variety. Most varieties fall close to the regression, with the exceptions that varieties polonica and haguenensis had 31 Figure l.--Relation between percentage of trees attacked by eucosma and number of attacks per plot. (Averaged over three plantations using only seedlots common to those plantations.) 32 cm .4 mmeHm Aucoonmmv poxomuud 40049 cm o4 om om O4 onGOQQmH.+ 4644444 + mwmooomowms ++onGoHom + wfiwamamuo mofimmsuon + wowamouoz maamoowuucouamm+. ++ manomeMI. moficoocma .+ 40444444 mamuasvm + + mommoposu mofiuonfi + + GGQEN Number of Attacks per Tree (average) 33 more trees attacked than varieties uraZensis and septen- trionalis, but the former varieties sustained fewer attacks per tree than the latter. However, only haguen- ensis was significantly (a = 1%) off the regression line and this may have occurred by chance. However, if these incongruities are real and not due to error, then they may mean that the two measurements reflect different resistance mechanisms in those varieties, or that interactions in the insect-host relationship are occurring in those varieties. For example, if the pre- sence of one insect influenced the presence of others, the two counts would be affected differently. Nevertheless, there is not sufficient reason at present to conclude that the two measurements are not equivalent at low and moderate levels of attack. Table 6 shows even more clearly than Table l a lat- itudinal trend in amount of attack. Northern varieties had the fewest trees attacked, southern varieties the most. It is noteworthy that the western European variety scotica is more similar to the central European varieties in percentage of trees attacked but to the southern Euro- pean varieties in number of attacks per tree. This var— iety is usually grouped with the southern European vari- eties in other traits: growth rate, color, needle length, and resistance to European pine sawfly (Wright et al., 1966). 34 The general consistency in results between the two measurements reinforces the conclusion that there are gen- etic differences in resistance to eucosma in Scotch pine. The next problem to be considered is what causes resis- tance . POSSIBLE MECHANISMS OF RESISTANCE GENERAL MECHANISMS Painter (1951) listed three major mechanisms of resis- tance. They are as follow. (1) Nonpreference is the tendency of a plant to be unattractive or repulsive to an insect. Plants are non- preferred if they do not present stimuli to which the insect has a positive response, or if they do present stimuli to which the insect has a negative response. These stimuli may be visual, tactile, or by taste or smell. Lack of a color attractant normally present would be an example of nonpreference resistance. (2) Antibiosis is the adverse effect of a plant on the biology of an insect. This resistance mechanism in plants is usually chemical. For example, a monoterpene may be present which is toxic to insects of a certain species. Some plants may be preferred for oviposition by the adults and yet have antibiotic effects on the larvae. (3) Tolerance is the ability of the plant to recover after an insect attack, or the ability to incur attack with- out detrimental effects. If an attacked plant were able to quickly form wound tissue, its resistance would be 35 36 classed as tolerance. The present evidence is insufficient to definitely eliminate any of these three general mechanisms from con- sideration. However, it seems improbable that the young Scotch pine twigs can exhibit tolerance to invasion by the large eucosma larvae. Some adverse effects on the tree undoubtedly result from any successful attack. Therefore, the two most likely manners in which resistance to eucosma may operate are (l) nonpreference by the adult for ovi- position and (2) antibiotic effects on the larvae. Resis- tance could be due to one or both of these general mecha- nisms. 37 DISTINCTIVE FEATURES OF RESISTANT AND SUSCEPTIBLE VARIETIES There was a general latitudinal trend in resistance -- southern varieties were attacked much more than northern ones. Therefore, I examined other traits which varied with latitude in a search for a possible mechanism of resistance. The among-variety differences in amount of attack were much greater than the within-variety differences, so I devoted most of my attention to varietal means. Height Height or growth rate is sometimes suggested as being a factor in insect resistance. For example, Wright et a1. (1967) found that susceptibility to European pine sawfly generally increased with increasing height of Scotch pine, and King (1971) reported that incidence of attack by eucosma on jack pine generally decreased with increasing height. Height measurements made in 1971 were available for the Kellogg and three other southern Michigan plantations. They are summarized in Table 6. It is apparent from this table that eucosma attack was not related to height. For example, varieties rigensis and armena were virtually the same height but had significantly different amounts of attack. The heavily attacked southern varieties were only of medium height and the fastest-growing variety, haguenen- sis, suffered only moderate attack (Tables 1 and 6). 38 Color The character which varies most consistently with latitude and eucosma resistance is winter foliage color. The southern-most varieties remain blue-green throughout the year. But in the autumn, trees from progressively more northern localities retain less green in the needles and develop a conspicuous yellow foliage color. In the spring, the color change reverses and the trees become green. This happens when there are three successive days above 600 F (White and Wright, 1967). In Michigan, this usually occurs in April. Eucosma oviposit in late April or early May. In the winter of 1970-71, I measured color at the Allegan plantation, using color grades of 0 = yellow to 9 = green, as used previously by Wright et a1. (1966). The results I obtained were very similar to those and other previous measurements. My color data were compared with the percentages of trees attacked at the same plantation in 1968 (Figure 2). There was a strong correlation between amount of attack and winter color. The varieties which remained greenest during the winter were attacked most heav- ily. I calculated the regression of number of trees attacked per plot on color, using seedlot means. The results are as follow: 39 Figure 2.--Relation between percentage of trees attacked by eucosma and winter foliage color. (Measured at Allegan in 1968 and 1970, respectively.) Trees Attacked (percent) 40 60 rhodopaea + + iberica 50 aquitana + + armena 0 4 baguenensis ++ herpynica pannonica borussica+- 30 polonica + (+rigensis + illyrica 20 septentrionalis + 'turalensis + 10 altaica 1apponica.+ O 0 2 3 4 5 6 7 8 9 Color Grade (0=yellow, 9=blue-green) FIGURE 2. 41 .Source df Mean Squares E Regression 1 10,879.9 91.74*** Residual 67 118.6 Total 68 ***) Indicates significance at the 0.1% level. This regression accounted for 58% of the variation in attack (r = .76; number of trees attacked per plot = -10.1 + '{6.9}{colorigrade}). If color is a factor in resistance, it may operate on female eucosma moths as they select trees for oviposition. Painter (1951) quoted a study by Weiss on the response of 50 Species of insects in several orders to different wave- lengths of light. Weiss found that ultraviolet and blue- blue-green light were most attractive to the insects and that red and yellow light were least attractive. Thus, it is possible that eucosma can differentiate foliage color and be attracted most to the trees which are greenest at the time of oviposition. Mineral Nutrients Steinbeck's (1965) foliar mineral nutrient accumula- tion data were re-examined. None of the 12 elements studied by him were correlated with resistance to eucosma. 42 Monoterpenes Amount of eucosma attack was also compared to Tobolski's (1968) data on percent composition of 11 corti- cal monoterpenes. A relationship of some of these with resistance would be reasonable since eucosma bores through the cortex on its way to the pith. Terpenes have been sug- gested as factors in insect resistance by previous invest- igators (Smith, 1965; Gilbert and Norris, 1968). However, upon comparing the varietal means for his data with those for my data there appeared no trends between resistance and any of the 11 monoterpenes, with two obscure exceptions. Among the southern and western varieties, scotica had the smallest percentage of attacked trees, the least a-pinene, and the most 3-carene; and iberica had the greatest percentage of attacked trees, the most a-pinene, and the least 3-carene. However, this relationship did not hold for all the varieties. 43 COMPARISON WITH RESISTANCE PATTERNS TO OTHER INSECTS Wright et a1. (1966) and Wright and Wilson (1971) found five other insects (European pine sawfly, white pine weevil, jack pine budworm, pine webworm, and pine root collar weevil) whose attack differed significantly among varieties of Scotch pine (Table 7). These studies were performed on the same seedlots and some of the same plan- tations as the present study. Comparison of Tables 1 and 6 with Table 7 indicates no common trends in resistance. Scotch pine resistance to eucosma is apparently unrelated to its resistance to these other five insects. 44 Table 7.--Varieta1 differences in susceptibility to attack by five insect pests, as reported by Wright et a1. (1966) and Wright and Wilson (1971). J_.._.__4.A AMLA AA- A. Percent of trees attacked by Variety Pine of Scotch European White Jack root pine pine pine pine Pine collar sawfly weevil budworm webworm.weevil Scandinavian and Siberian Varieties Zapponica 0.2 12 39 - - 14 mongolica 1.1 20 52 0.0 53 altaica .9 45 21 - - 30 septentrionalis 2.4 57 43 .0 37 rigensis 6.1 76 46 1.2 45 uralensis 3.2 86 34 .0 40 Central European Varieties polonica 19.1 77 80 .0 67 borussica 20.6 41 55 .0 68 hercynica 19.5 80 54 1.9 43 haguenensis 25.7 65 42 1.1 70 'East Anglia' 26.5 -- -- - - 39 pannonica 20.1 97 25 10.0 52 iZZyrica 18.7 68 54 10.0 10 West and South European Varieties 'North Italy' 11.6 -- -- 3.8 10 scotica 6.5 -- -- 7.5 18 iberica 10.6 15 22 7.0 17 aquitana 9.6 72 23 2.0 12 rhodopaea 9.3 72 38 10.0 18 armena 6.7 46 35 10.0 12 Significance, variety ** ** ** ** ** Significance, within ns * * ns ns variety *, **) Indicates significance at the 5 and 1% levels, respectively. PRACTICAL APPLICATION Differences among varieties were much greater than differences within varieties. So the most gain in resis- tance can be made by selecting among the varieties. Var- iety uraZensis, which is intermediate in growth rate, averaged fairly low in amount of attack. Variety haguen- ensis, the fastest-growing variety, was intermediate in percentage of trees attacked and below average in number of attacks per tree. However, neither of these varieties are preferred for Christmas tree planting. The southern and western varieties are most commonly planted for this pur- pose. These varieties were least resistant to eucosma. Of the varieties suitable for Christmas-tree use, variety aquitana had by a small margin the fewest attacks per tree. It also has good color, short needles, modest growth rate, high resistance to pine root collar weevil, and moderate resistance to European pine sawfly. Differences among seedlots within varieties were significant at two plantations, but no particular seedlots were exceptional in resistance at both. The within—variety variation seemed to be at random geographically. Growers who wish to procure quality seed of a particular variety 45 46 can only expect seed of average quality for that variety, regardless of what part of the range it comes from. I was not able to determine the cause of resistance, but it is not necessary to know this for breeding purposes. Color was highly correlated with resistance, but probably not enough to warrant selection on the basis of color, especially if there is a moderate level of insect attack with which to distinguish resistant trees. SUMMARY Larvae of the Eucosma gZorioZa moth kill young twigs on Scotch pine, causing unsightly damage. To determine if some varieties of this tree are genetically resistant to eucosma, attack was measured on 110 seedlots of Scotch pine belonging to 19 varieties. The trees were planted at three locations in southern Michigan: Allegan County (70 seedlots), Shiawassee County (76 seedlots), and Kalamazoo County (106 seedlots). Each plantation was measured in either one or two different years. Most results were consistent from plantation to plantation and year to year. There were highly significant differences in attack among seedlots in all plantations and years, indicating that there are genetic differences in resistance. Most of the variation was due to differences among varieties. At the most heavily-attacked plantation, the short northern varieties had from 1 to 4 attacks per tree, the tall cen- tral EurOpean varieties had from 2 to 6 attacks per tree, and the medium-height southern and western varieties had from 6 to 10 attacks per tree. Some variation was due to differences among seedlots 47 48 within varieties, but no seedlots were significantly better or worse than their varietal means at every plantation. Of the characters studied in searching for a possible mechanism of resistance, winter foliage color was most highly correlated with resistance. Yellow varieties were least-attacked and green varieties were most-attacked. Height, mineral nutrients, and resistance patterns to other insects were not related with susceptibility to attack. There was a very limited correlation between two cortical monoterpenes and resistance to eucosma. The varieties which are most preferred for Christmas tree planting are also most susceptible to eucosma, but variety aquitana was the least-attacked member of this group. LIST OF REFERENCES 49 LIST OF REFERENCES Austin, L., J. S. Yuill, and K. G. Brecheen. 1945. Use of shoot characters in selecting ponderosa pines resistant to resin midge. Ecol. 26: 288- 296. Batzer, H. 0. 1962. White-pine weevil damage differs significantly by seed source on two northern Minnesota jack pine plantations. U. S. Forest Serv., Lake States Forest Expt. Sta. Tech. Note 618. 2 pp. Bennett, W. H. 1954. The effect of needle structure on the susceptibility of hosts to the pine needle miner Exoteleia pinifoZieZZa (Chamb.)(Lepidoptera: Gelechiidae). Canadian Ent. 86: 49-54. Butcher, J. W. and A. C. Hodson. 1949. Biological and ecological studies on some Lepidopterous bud and shoot insects of jack pine (Lepidoptera-Olethreutidae). Canadian Ent. 81: 161-173. Cochran, W. G. and G. M. Cox. 1957. Experimental designs, 2nd edition. John Wiley and Sons, Inc. 611 pp. DeBoo, R. F. 1967. Investigations of the importance, biology, and control of Eucosma gloriola Heinrich (Lepidoptera: Olethreutidae) and other shoot and tip moths of conifers in New York. Dissert. Abstr. 283 (1): 220-221. Drooz, A. T. 1960. White—pine shoot borer (Eucosma glori- oZa Heinrich). Econ. Ent. 53: 248-251. Gerhold, H. D., E. J. Schreiner, R. E. McDermott, J. A. Winieski (eds.). 1966. Breeding pest-resistant trees. Pergamon Press, Ltd. 505 pp. Gilbert, B. L. and D. M. Norris. 1968. A chemical basis for bark beetle (Scolytus) distinction between host and non-host trees. Insect Physiol. 14: 1063-1068. 50 Graham, S. A. and L. G. Baumhofer. 1930. Susceptibility of young pines to tip-moth injury. J. For. 28: 54-65. Hall, R. C. 1942. Control of the locust borer. U.S.D.A. Circ. 626: 19 pp. Harris, P. 1960. Production of pine resin and its effect on survival of Bhyacionia buoliana (Schiff.) (Lepidoptera: Olethreutidae). Canadian J. Zool. 38: 121-131. Haynes, D. L. and J. W. Butcher. 1962. Studies on host preference and its influence on European pine shoot moth success and development. Canadian Ent. 94: 690-706. Heinrich, C. 1931. A new pine moth from Connecticut. Ent. Soc. Wash. Proc. 33: 196-197. Holst, M. 1963. Breeding resistance in pines to Rhyaci- onia moths. World Consult. Forest Genet. Tree Improve. Proc. (Stockholm) 2: 17 pp. King, J. P. 1971. Pest susceptibility variation in Lake States jack pine seed sources. U.S.D.A. Forest Serv. Res. Pap. NC-53: 10 pp. Libby, W. J. 1958. The backcross hybrid Jeffrey x (Jeffrey X Coulter) pine. J. For. 56: 840-842. MacAloney, H. J. and J. W. Johnston. 1933. White-pine weevil attack on Scotch pine. J. For. 31: 26. Miller, J. M. 1950. Resistance of pine hybrids to the pine reproduction weevil. U. S. Forest Serv., Calif. Forest and Range Exper. Sta. Res. Note 68: 17 pp. Miller, W. E. and H. J. Heikkenen. 1959. The relative sus- ceptibility of eight pine species to European pine shoot moth attack in Michigan. J. For. 57: 912-914. Neugebauer, W. 1954. (The control of Rhyacionia bquiana.) Forest. Abstr. 15: 471. Newman, J. H. 1968. First records of the white pine shoot borer, Eucosma gZorioZa (Lepidoptera: Olethreutidae) in Michigan. Mich. Ent. 1: 267-270. 51 Painter, R. H. 1951. Insect resistance in crop plants. Macmillan and Co. 520 pp. Ruby, J. L. 1964. The correspondence between genetic, morphological, and climatic variation patterns in Scotch pine. Mich. State Univ., Ph.D. Thesis. Rudolf, P. O. and R. F. Patton. 1966. Genetic improve- ment of forest trees for disease and insect resis- tance in the Lake States, pp. 63-68. In Gerhold et al. (eds.), Breeding pest-resistant trees. Pergamon Press, Ltd. 505 pp. Schantz—Hansen, T. and R. A. Jensen. 1952. The effect of source of seed on growth of jack pine. J. For. 50: 539-544. Schonborn, A. von. 1966. The breeding of insect-resistant forest trees in central and northwestern Europe, pp. 25-27. In Gerhold et al. (eds.), Breeding pest-resistant trees. Pergamon Press, Ltd. 505 pp. Schreiner, E. J. 1949. Poplars can be bred to order. U.S.D.A., Yearbook of Agriculture, 1949: 153-157. Shenefelt, R. D. and D. M. Benjamin. 1955. Insects of Wisconsin forests. Univ. Wisc. Exten. Circ. 500: 110 pp. Skuhravy, V. and R. Hochmut. 1970. (Density of infesta- tions of Thecodiplosis brachyntera on Pinus syl- vestris of varying provenance.) Forest. Abstr. 31: 359-360. Smith, R. 1965. Effect of monoterpene vapors on the western pine beetle. J. Econ. Ent. 58: 509-510. Sokal, R. R. and F. J. Rohlf. 1969. Biometry. W. H. Freeman and Co. 776 pp. Steinbeck, K. 1965. Foliar mineral accumulation be sev- eral Scotch pine (Pinus sylvestris L.) provenances. Mich. State Univ., Ph.D. Thesis. Tobolski, J. J. 1968. Variations in monoterpenes in Scotch pine (Pinus sylvestris L.). Mich. State Univ., Ph.D. Thesis. 52 Vofite, A. D. 1946. (Pissodes piniphilus in the 'De Hoge Veluwe' National Park.) Forest. Abstr. 8: 442-443. White, D. P. and J. W. Wright. 1967. Pigment changes in Scotch pine (Pinus sylvestris L.) induced by con- trolled environment. Mich. Acad. Sci., Arts, and Letters Papers 52: 55-62. Wright, J. W. and I. W. Bull. 1963. Geographic variation in Scotch pine. Results of a 3-year Michigan study. Silvae Genetica 12: 1-25. Wright, J. W., S. S. Pauley, R. B. Polk, J. J. Jokela, and R. A. Read. 1966. Performance of Scotch pine var- ieties in the North Central region. Silvae Gene- tica 15: 101-140. Wright, J. W. and L. F. Wilson. 1971. Dramatic differences in resistance of Scotch pine varieties to the pine root collar weevil. In press. Wright, J. W., L. F. Wilson, and W. K. Randall. 1967. Differences among Scotch pine varieties in suscept- ibility to European pine sawfly. For. Sci. 13: 175-181. APPENDIX 53 Table A1.--Varieta1 differences in percentage of trees attacked by eucosma at Allegan and Rose Lake in 1970, a year of heavy infestation at those plantations. The data were analyzed by the "chi-square" test of proportions. Varieties not sharing the same letter are significantly different at the 5% level. .— _4‘__ A... 4 _ - M...— Variety Trees attacked Significance of Scotch (% of total) of differences pine Allegan Rose Lake Allegan Rose Lake Scandinavian and Siberian Varieties Zapponica 49 79 b b mongolica 18 32 a a altaica 88 75 c b septentrionalis 94 80 c b rigensis 98 81 c b uraZensis 98 73 c b Central European Varieties poZonica 96 79 c b borussica 98 73 c b hercynica 95 82 c b haguenensis 94 76 c b 'East.Anglia' -- 75 c b pannonica 100 89 c b iZZyrica ; 100 86 c b West and South EurOpean Varieties 'North Italy' -- 92 c b scotica -- 100 c b iberica 98 94 c b aquitana 99 94 c b rhodopaea 99 95 c b armena 99 95 c b 54 Table A2.--Number of attacks by eucosma in each seedlot at all plantations in 1970, and average color grade of each seedlot at Allegan in 1970. Plantation name and number Variety, MSFG and number of trees per seedlot (plots x 4) seedlot number, Alle- Rose Kell- Alle- and country gan Lake ogg All gan of originl 11-61 12-61 2-61 plantations 11—61 40 28 247 92 Per tree Per tree Average Color Number of Attacks Grade2 Zapponica 229 FIN 30 -- 1 -- --- 2.3 546 SWE 54 39 1 94 1.0 3.5 547 SWE -- -- 2 -- -—- --- 548 SWE -- -- O -- --- --- 549 SWE -- -- 2 -- --- --- mongolica 234 SIB -- -- 11 -- --- --- 254 SIB 13 13 0 26 0.3 1.5 aZtaica 227 SIB 122 -- 7 -- --- 3.1 255 SIB 131 56 10 197 2.1 2.5 256 SIB 76 55 2 133 1.4 2.0 septentrionalis 201 NOR 230 169 8 407 4.4 5,3 222 SWE 155 101 7 263 2.9 4.2 228 FIN —- -— 2 -- --- --- 230 FIN 154 93 12 259 2.8 3.2 232 FIN‘ -- -- 5 -- --- --- 233 FIN -- —- 6 -- --- --- 273 NOR 139 110 5 254 2.8 5.0 274 NOR 172 79 4 255 2.8 4.0 521 SWE 135 105 18 258 2.8 4.7 522 SWE 194 86 4 284 3.1 4.0 523 SWE 115 53 5 173 1.9 3.9 524 SWE 149 63 12 224 2.4 4.2 543 SWE 180 47 8 235 2.6 4.6 544 SWE 154 73 9 241 2.6 4.2 545 SWE 129 72 7 208 2.3 3.9 Table A2 (cont'd.). rigensis 223 224 541 542 550 uraZensis 257 258 259 260 polonica 211 317 borussica 202 210 hercynica 203 204 207 208 209 248 305 306 307 308 309 310 311 312 313 314 315 319 525 526 527 528 529 LAT LAT SWE SWE SWE URA URA URA URA POL POL GER GER GER GER GER GER GER GER CZE CZE CZE CZE CZE CZE CZE CZE CZE CZE CZE AUS GER GER GER GER GER 168 173 167 149 175 152 227 134 106 155 100 155 116 79 87 84 79 61 56 65 48 113 40 115 74 123 73 108 115 116 170 13 19 11 23 28 18 12 13 17 25 14 16 13 16 23 16 19 19 13 11 16 28 20 13 20 NNWUJ o o o o 03qu NOONkN 0J0) I Olei-‘DINN mxlxlmmmmq o o o o o o o o \lHomqkomH 56 Table A2 (cont'd.). Plantation name and number Variety, MSFG and number of trees per seedlot (plots x 4) seedlot number, Alle- Rose *Kell- Alle- and country gan Lake ogg A11 gan of origin1 11-61 12-61 2-61 lantations 11-61 40 28 24 52 Per tree Per tree Average Color Number of Attacks Grade2 haguenensis 206 GER 122 51 10 183 2.0 7.5 250 GER -- 68 17 -- --- --- 251 GER 93 87 17 197 2.1 8.1 252 GER 113 99 20 232 2.5 7.4 253 GER 112 91 11 214 2.3 7.5 236 FRA -- -- 16 -— --- --- 237 FRA -- -- 9 -- --- --- 241 FRA 132 80 12 224 2.4 7.9 318 BEL 108 44 10 162 1.8 7.6 530 BEL 97 54 17 168 1.8 7.6 'East Anglia' 269 ENG -- 86 11 -- --- --- 270 ENG -- -- 14 -- --- --- pannonica 552 HUN -- 230 -- -- --- --- 553 HUN 200 76 18 294 3.2 6.7 illyrica 242 YUG 179 131 24 334 3.6 6.8 'North Italy' 554 ITA -- 270 -- -~ --- --- 555 ITA -- -- 27 -- --- --- 556 ITA -- 258 20 -- --- --- 557 ITA -- 232 26 -- --- —-- scotica 265 SCO -- -- 17 -- --- --- 266 SCO -- -- 12 -- --- --- 267 SCO -- 283 13 -- --- --- 268 SCO -- -- 17 _— ___ -_- 57 Table A2 (cont'd.). iberica 218 SPA 203 198 30 431 4.7 8.8 219 SPA 172 199 28 399 4.3 8.7 245 SPA 141 325 14 480 5.2 8.6 246 SPA 200 318 52 570 6.2 7.5 247 SPA 165 261 32 458 5.0 8.3 aquitana 212 FRA -- -- 14 -- --- --- 238 FRA 219 261 15 495 5.4 8.4 239 FRA 191 275 17 483 5.3 8.4 240 FRA -- -- 40 -- --— --- 316 FRA -- -- 26 -- --- --- 320 FRA -— 219 24 -— --- --- 249 AUS -- 183 -- -- --- --- 235 FRA 151 96 20 267 2.9 7.6 rhodopiea 243 GRE 248 174 32 454 4.9 6.6 244 GRE 195 178 16 389 4.2 7.1 271 GRE 156 -- 39 -— --- 7.2 272 GRE -- 118 13 -— --- --- 551 GRE 344 -- 38 -- --- 6.5 armena 213 TUR 282 251 13 546 5.9 7.4 214 TUR -- -- 19 -- --- --- 220 TUR 171 179 33 383 4.2 7.8 221 TUR 271 198 21 490 5.3 7.2 261 GEO -- 248 22 -- --- --- 262 GEO -- -- 29 -- --- --- 263 GEO -— —- 22 -- --- --- 264 GEO -- -- l9 —- --- --- other3 205 AUS -- -- 27 -- --- --- 225 N.Y. 147 107 23 277 3.0 8.1 Overall average 153.3 126.0 15.8 286.0 3.1 6.4 1) AUStria, BELgium, CZEchoslovakia, ENGland, FINland, FRAnce, GEOrgian SSR, GERmany, GREece, HUNgary, ITAly, LATvian SSR, NORway, POLand, SCOtland, SIBeria, SPAin, SWEden, YUGoslavia, URAl Mountains. 2) Trees were graded for color on the basis of 0 = yellow to 9 = blue-green. 3) These two seedlots were not considered in the results because of their questionable origin. 58 Table A3.--Number of trees attacked by eucosma in each seedlot at all plantations and in all years. . Plantation name and number, year of count, Variety, MSFG and number of trees per seedlot (plots x 4) seedlot number, Alle- Rose Kell- Alle- Rose and country gan Lake ogg gan Lake of origin1 11-61 12-61 2-61 11-61 12-61 I968 I969 1979' 1970 1970 28 28 24 40 28 Number of Attacked Trees Zapponica 229 FIN 1 -- 1 17 -- 546 SWE 0 7 1 22 22 547 SWE -- -- 2 -- -- 548 SWE -- -- 0 -- -- 549 SWE -- -- 2 -- -- mongolica 234 SIB -- -- 7 -- '- 254 SIB -- 0 0 7 9 altaica 227 SIB 4 -- 5 40 -- 255 SIB 5 8 6 35 22 256 SIB 0 9 2 31 20 septentrionalis 201 NOR 11 16 4 40 28 222 SWE 6 7 6 40 23 228 FIN -- -- 2 -- -- 230 FIN 1 3 10 38 23 232 FIN —— -- 5 -- -- 233 FIN -- -- 5 " “ 273 NOR 3 11 4 34 24 274 NOR 3 6 2 38 23 521 SWE 8 9 11 37 26 522 SWE 1 8 2 40 21 523 SWE 0 2 3 37 18 524 SWE 3 8 7 37 20 543 SWE 4 6 7 38 14 544 SWE 8 6 6 37 25 545 SWE 2 3 4 34 23 Table A3 (cont'd.). 59 rigensis 223 LAT 224 LAT 541 SWE 542 SWE 550 SWE uralensis 257 URA 258 URA 259 URA 260 URA polonica 211 POL 317 POL borussica 202 GER 210 GER hercynica 203 GER 204 GER 207 GER 208 GER 209 GER 248 GER 305 CZE 306 CZE 307 CZE 308 CZE 309 CZE 310 CZE 311 CZE 312 CZE 313 CZE 314 CZE 315 CZE 319 AUS 525 GER 526 GER 527 GER 528 GER 529 GER oomwroox \D\l 10 12 0000 39 39 38 40 39 39 39 38 39 40 38 24 22 23 22 21 22 20 19 25 19 22 19 60 Table A3 (cont'd.). Plantation name and number, year of count, Variety, MSFG and number of trees per seedlot (plots x 4) seedlot number, Alle- Rose Kell— Alle- Rose and country gan Lake ogg gan Lake of origin1 11-61 12-61 2-61 11-61 12-61 1968 1969 1970 1970 1970 28 28 24 40 28 Number of Attacked Trees haguenensis 206 GER 12 10 6 39 15 250 GER -- 13 ll -- 26 251 GER 15 9 13 35 24 252 GER 15 15 13 39 24 253 GER 10 11 10 38 23 236 FRA -- -- 11 -- -- 237 FRA -- —— 8 -- -- 241 FRA 10 6 6 37 24 318 BEL 6 9 7 36 19 . 530 BEL 10 10 6 39 15 'East Anglia' 269 ENG -- 9 8 -~ 21 270 ENG -- -— 10 -- -- pannonica 552 HUN ' -- 17 -- -- 26 553 HUN 10 13 11 40 24 iZZyrica 242 YUG 7 13 15 40 24 'North Italy' 554 ITA -- 17 -- -- 25 555 ITA -- -- 14 -- -- 556 ITA -- 16 12 -- 27 557 ITA -- 16 13 -- 25 scotica 265 SCO -- -- lO -- -- 266 SCO -- -- 8 -- -- 267 SCO -- 10 11 -- 28 268 sec -- —- 12 -- -- 61 Table A3 (cont'd.). iberica 218 SPA 12 12 12 4O 26 219 SPA 21 16 14 40 27 245 SPA 9 18 11 39 26 246 SPA 16 20 17 39 27 247 SPA 15 20 17 38 26 aquitana 212 FRA -- -- 11 -- -- 238 FRA 13 14 ll 40 26 239 FRA 11 13 10 39 25 240 FRA -- -- 16 -- -- 316 FRA -- -- 10 -- -- 320 FRA -- 19 15 -- 27 249 AUS -- l4 -- -- 26 235 FRA 14 9 11 40 27 rhodopaea 243 GRE 15 14 14 40 26 244 GRE 14 17 11 40 28 271 GRE 9 -- 16 40 -- 272 GRE -- 10 8 —- 26 551 GRE 20 -- 18 38 -- armena 213 TUR 14 18 9 39 27 214 TUR -- -- 9 -- -- 220 TUR 7 17 16 40 27 221 TUR 14 14 ll 40 25 261 GEO -- 18 13 -- 27 262 GEO -- -- ll -- -- 263 GEO -- -- 13 -- -- 264 GEO -- -- 12 -- -- other2 3 205 AUS -- -- 15 -- -- 225 N.Y. 13 15 14 4O 26 Overall average 8.9 11.2 9.4 37.4 23.2 1)AUStria, BELgium, CZEchoslovakia, ENGland, FINland, FRAnce, GEOrgian SSR, GERmany, GREece, HUNgary, ITAly, LATvian SSR, NORway, POLand, SCOtland, SIBeria, SPAin, SWEden, YUGoslavia, URAl Mountains. 2)These two seedlots were not considered in the results because of their questionable origin. 93 03175 4033 31 I I I l I I I I II I l' l | I all I 'III III I I l I II I I I'll. I l I '1']. ll ll I l 41