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ABSTRACT

DDT RESIDUES IN A MOSQUITO CONTROL PROGRAM
AT THE KELLOGG BIOLOGICAL STATION

by David R. Osborne

Following the use of DDT sprays for the purpose of con-
trolling Dutch elm disease, many people have reported large
numbers of birds either dead or dying of symptoms commonly
associated with chlorinated hydrocarbon poisoning. However,
a mosquito control program using a mixture of DDT (1,1,1-
trichloro-2,2-bis(p—chlorophenyl) ethane) and Chlordane
(l,2,4,5,6,7,8, 8-octochloro-2,3,3a,4,7,7a-hexahydro—4,6-
methanoidene), in effect since 1954 at the W. K. Kellogg Gull
Lake Biological Station, Kalamazoo County, Michigan, has been
associated with high bird populations and apparent lack of
any unusual bird mortality. This study was undertaken during
the summer of 1962 in an attempt to discover, under actual
field conditions, the reasons for the apparent lack of bird
mortality in the program at the Biological Station.

For this study samples of soils, earthworms, leaves,
fruits, and elm bark were collected and quantitatively
analyzed by the Schechter—Haller method for DDT (Schechter

t 1., 1945). The levels of DDT in eggs and tissues of

David R. Osborne

young and adult birds from the study area and similar areas
were determined, and the persistence and the availability
of DDT to birds was studied.

The results of the soil analyses indicated that most of
the DDT was lost from soil in open areas, but persisted in
low concentrations under shrubs, and increased as much as
28.5 per cent in soils at the base of elms during a 35 week
interim between samplings, presumably due to run-off from the
trunks of the trees.

Analyses of spring and summer specimens of earthworms
showed that DDT was present in their tissues in levels below
15 ug. of DDT/g. The results also showed that earthworms
often contained higher levels of DDT than did the soils from
which they were taken.

The analyses of plant and animal materials disclosed DDT
in variable amounts in the study area, thus making it widely
available to birds with different feeding habits. DDT levels
ranged from 0-1388 ug. of DDT/g. on leaves, 5.28-146.4 ug.
of DDT/g. on elm bark, and 0-10 ug. of DDT/g. on fruit. A
sample of camel crickets (Ceuthophilus maculatus) contained
2.16 ug. of DDT/g.

Studies of persistence in plant material showed that

62.2 per cent of the DDT was lost from the plant surface

David R. Osborne

after 19 days while a 77.2 per cent loss occurred after
eight months. Loss of DDT from the trunks of elms ranged
from 75.9-84.3 per cent over eight months.

DDT ranging from 2.75 to 15.2 ug. of DDT/g. was found
in unhatched eggs and young birds.

Results from the analyses of the tissues of 23 birds
including 13 from the study area showed that levels of DDT
ranged higher in the brain than in liver or breast muscle.
Analyses of brain tissues from 13 dead birds found in the
study area in 1962 showed that in most cases DDT was not
present in sufficient quantities to justify the conclusion
that DDT was the cause of death. Only three of the birds
analyzed had 50 ug. or more of DDT in the brain.

The brain tissue of eight cedar waxwings obtained from
outside the study area averaged 20.6 ug. of DDT/g.

The evidence obtained in this study, plus the fact that
no birds were found in tremors in the summer of 1962,supports
the conclusion that lack of mortality that summer was due to
the low levels of DDT present in the study area, which
resulted in sublethal accumulations of DDT in the tissues

of birds.

DDT RESIDUES IN A MOSQUITO CONTROL PROGRAM

AT THE KELLOGG BIOLOGICAL STATION

BY

L‘
David Rfi6sborne

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of ‘

MASTER OF SCIENCE
Department of Zoology

1963

AC KN OWLE DGME NT S

I wish to express my sincere appreciation to Dr. George
J. Wallace, Professor of Zoology, for his interest, direc-
tion, and guidance throughout this investigation. I am also
indebted to Dr. Erwin J. Benne, Professor of Biochemistry,
for his help and advice on the technical procedures for
analysis, and for the use of facilities in the department
of Biochemistry where the analytical work was performed.
Appreciation is also expressed to Dr. T. wayne Porter, Pro—
fessor of Zoology, for his helpful suggestions while serving
on the author's guidance committee.

Grateful thanks are also due to Dr. Arthur R. WOlcott,
Associate Professor, Soil Science, for classifying the soil
samples, and to those individuals who submitted dead birds

for analysis.

ii

LIST OF TABLES .

TABLE OF CONTENTS

LIST OF ILLUSTRATIONS . .

INTRODUCTION . .

GENERAL DESCRIPTION AND LOCATION

METHODS . . . .

Analysis for DDT . . .

PRESENTATION OF DATA . . .

DDT Residues in Soil .

DDT Residues

DDT Residues

DDT Residues

DDT Residues

in

in

in

in

Earthworms . .

Leaves,

Eggs .

Birds

Fruit,

GENERAL DISCUSSION AND CONCLUSIONS

SUMMARY . . . .

LITERATURE CITED

iii

Page

iv

11
ll
16
20
27
29
36
39

43

Table

DDT

DDT

DDT

DDT

DDT

Found

Found

Found

Found

Found

in

in

in

in

in

LIST OF TABLES

Soils

Earthworms

Leaves,

Eggs

Birds

Fruit,

iv

and Bark

Page
13

17
23
28

31

LIST OF ILLUSTRATIONS

Figure
1 Major Vegetation at the Kellogg Gull Lake

Biological Station . . . . . . . . . . . .

2 Location of Soils Collected at the Kellogg
Biological Station . . . . . . . . . . . .

3 Location of Plant and Animal Material
Collected at the Kellogg Biological Station

Page

12

21

INTRODUCTION

\
A spray progranl for mosquitt> control, using a mixture

of DDT (1,1,1—trichloro-2,2—bis(p-chlorophenyl) ethane) and
Chlordane (1,2,4,5,6,7,8,8-octochloro-2,3,3a,4,7,7a—hexa—
hydro—4,7-methanoidene), has been in progress each summer
since 1954 at the W. K. Kellogg Gull Lake Biological Station,
Kalamazoo County, Michigan. Several unpublished reports in
1959, 1960, and 1962 indicate this area had relatively high
bird populations and good though variable nesting success
(Jensen, 1959; Moldenhauer, 1960; Johnson, 1962). In con-
trast, spray programs on the Michigan State University Cam-
pus with DDT, for Dutch elm disease, also in progress since
1954, resulted in a sharp decline of robins by 1957 (Mehner
and Wallace, 1959), and high bird mortality in 1958, 1959,
and 1960 (Wallace, 1960; Wallace _t_§l,, 1961). Chemical
analyses of birds and feeding experiments indicated that the
high bird mortality was a direct result of ingestion of
lethal amounts of DDT in areas sprayed for the control of
Dutch elm disease (Bernard, 1963).

This study was undertaken to try to discover reasons for
the apparent lack of mortality from DDT, under actual field

conditions, at the Biological Station in contrast with the

relatively low population and obvious mortality on the
Michigan State University Campus. Hence, studies were made
to determine the levels of DDT present in the environment,
its persistence and availability to birds, and the amounts
accumulated by birds.

The study area had been sprayed for the past 9 summers
with several applications of DDT. In each case the spray
mixture consisted of 4 pounds of 50 per cent wetable DDT
powder and 2 pounds of 40 per cent wetable Chlordane com-
bined in 100‘gallons of water. Two applications of this
mixture, each covering a separate portion of the grounds,
were used to spray the 32—acre site on 14 June 1962 and
theoretically represented an application rate of 0.125 pounds
of DDT/acre.

Spraying was by pressure apparatus (the type commonly
used in orchard spray programs) connected to a 100 gallon
tank-trailer which was pulled by jeep. All lawns, shrubs,
and low vegetation were sprayed thoroughly. Precautions
were taken not to spray known active nest sites. Although
the program was primarily for mosquito control, trunks of
elms were sprayed to a height of 40 feet.

Chemical analyses for residues of DDT in field programs

for mosquito control are scarce. Most studies are based on

field observations only. In most instances there has been
no observed bird mortality in mosquito control areas re-
ceiving one pound or less of DDT/acre (Adams et_§1,, 1949;
Couch, 1946; Erickson, 1947). Two to three pounds of DDT/
acre, in repeated treatments, have been found to affect
insectivorous birds directly, or indirectly through their
food supply, eliminating flying insects on which they feed

(Rogers, 1948; Rudd t al,, 1956). Bird mortality is se-

vere at an application rate of five pounds of DDT/acre
(Hotchkiss §§_§l,, 1946).

George (1957) has shown that where formerly multiple
applications of 0.1 to 0.5 pounds of DDT/acre were used,
now dosages may range up to 2 pounds of DDT/acre for mos-
quito control; the increase in dosage was necessary because
of resistance to DDT developed by insects.

In the type of spray program used for mosquito control,
the application may not be uniform; that is, one spot may
receive more DDT than an adjacent one and some shrubs more
than others. Even at a low average application rate of
0.125 pounds of DDT/acre, lethal amounts of DDT may be avail—
able to birds due to the variability of application and also

to accumulations in plant and animal tissues. Kendeigh

(1947) has suggested that bird mortality might occur even

when application rates are below the acute toxicity level
for a given species. He found that due to uneven coverage,
DDT dosages obtained after spraying were 15 pounds/acre in
some areas supposedly sprayed at a rate of 1 pound of DDT/
acre.

Availablility of DDT to birds is possible in many ways,
depending upon their feeding habits. Animals or plants
may act as carriers of the poison. The fact is now well—
known that earthworms build up DDT residues and serve as a
source of contamination to robins (Barker, 1958; Bernard,
1963).

Therefore, the purpose of this study was to determine
the levels of DDT in various bird tissues, soils, plants,
fruits, and other carriers which might serve as a source of
DDT to birds.

This investigation does not include an analysis or a
determination of the effects of Chlordane used in the site.
Nor was the effect of DDT storage in fat of summer birds

studied.

GENERAL DESCRIPTION AND LOCATION
OF THE STUDY AREA

The W. K. Kellogg Biological Station of Michigan State
University is situated on the north shore of Gull Lake in
Kalamazoo County, Michigan. The main grounds cover an area
of approximately 32 acres, bounded by county roads on the
north and east sides, Gull Lake on the south, and a township
park on the west. A small additional acreage used as a
rifle range is located adjacent to and just north of the
main entrance. The main area is enclosed by a fence except
for the Gull Lake shoreline. Roads, dormitories, labora-
tories and other buildings have been constructed on the
grounds.

The landscape consists mainly of rolling hills of grass,
dotted with trees and clumps of shrubs. Native trees are

mainly elm (Ulmus americana), oak (Quercus sp,), and maple

 

(Ag§£_§p,). Shrubs are primarily of honeysuckle (Lonicera
§p,), lilac (Syrinqa £23) and hazel (Corylus sp,), found in
isolated clumps, in open expanses next to buildings, and
along fence rows. A mature apple orchard has been estab-
lished at the west end of the study area. Two wooded areas
(see figure 1), primarily of oak, are also present. A

stand of tall elms shades the west side of the tennis court.

Many exotic plants, introduced by W. K. Kellogg, are also
found on the grounds.

Figure 1 indicates the major vegetation of the study
area. Isolated trees in open grassy areas are not shown.

The symbols used are as follows:

A. shrubs

B. woods

C. stands of elms
D. orchard

E. grass

Figure 1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

mox- Vegetation at the xonoggaun Lake

Biological Station. Kalamazoo 00.. Michigan

  

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METHODS

Samples of soil, bark, plants, fruits, earthworms, eggs,
nestlings, and adult birds in the study area were collected
and analyzed for DDT. Most specimens were collected from
28 June to 8 August 1962. However, a collection of plant and
animal material was made on 7 April 1963, before any spray-
ing was done that year. At no time did any of the birds
analyzed show symptoms of tremors commonly associated with
chlorinated hydrocarbon poisoning.

Chemical determination of DDT residues was made by the
Schechter-—Haller method of analysis (Schechter g§.§;,, 1945).
Since facilities for analysis were not available at the sta-
tion all samples were placed in plastic bags, frozen, and
stored. The samples remained frozen until determinations for
DDT could be made in an on-campus laboratory of the Department
of Biochemistry. Freezing does not alter the stability of

DDT (Lichtenstein t al,, 1958).

The earthworms collected were identified by means of the
key in Ball and Curry (1956). Harlow's Trees 9§_the Eastern
United States and Canada was used for identification of trees

and shrubs. The scientific names for the birds mentioned are

from Zimmerman and Van Tyne (1959).

ANALYSIS FOR DDT

Procedure. - Briefly, the method of analysis used consisted

 

of macerating the material with anhydrous sodium sulfate and
quartz sand, removing the DDT with an organic solvent (diethyl
ether- petroleum ether mixture), nitrating the residue, and
separating the nitrated DDT from the acidified aqueous solu-
tion with ether. DDT in the ether extract was evaluated by
the procedure of Schechter _t__l, as preScribed by the ASSOCi-
ation of Official Agricultural Chemists (1955). The ether-
petroleum ether portion containing DDT was filtered, evap-
orated, and the residue taken up in Benzene. Finally, al-
coholic sodium metholate was added to an alequot of the
benzene solution to develop the characteristic blue-colored
complex. The per cent transmittancy was determined with a
Beckman B spectrophotometer at a wave length of 600 milli-
microns. DDT was then calculated from a standard curve
prepared with a 3 to l p,p' o,p' - DDT mixture and the re-

sults expressed in micrograms of DDT/gram of sample (ug. of

DDT/9.).

Interference. — The Schechter-Haller method is generally
specific and accurate. However, other insecticides may

interfere in the nitration process or with the colormetric

lO

evaluation of DDT. The principal insecticides known to in-
terfere are DNB and DNP (the nitro l, 1 bis (p—chlorophenyl)
butane and propane analogues of DDT), TDE (dichloro-2,2-bis
(Chlorophenyl) ethane), DDE (l, 1-dichloro—2,2 bis (p-chloro-
phenyl) ethylene), and Methoxychlor (l,l,l-trichloro-2,2-bis
(p-methoxyphenyl) ethane). However, none of these were used
in the control program in this area.

Since Chlordane was used in the spray formulation and
was undoubtedly present in the samples analyzed, its effect
on the chemical analysis for DDT was determined. Known
amounts of DDT and Chlordane, in various concentrations,
were mixed and analyzed by the Schechter-Haller method.
Chlordane, even in high concentrations, did not affect the
DDT values beyond the normal limits of reproducability with

this procedure.

General Considerations. - In order to correct for deviations
in technique and effects of the individual samples it was
necessary to carry a blank (uncontaminated sample) along with
each test series. Due to a lack of soil, plants, and birds
known to be free of DDT, substitute blanks were used. These
consisted of benzene solutions, chemically pure sand, "Poll
feed", and birds. The birds used were "road-kills" found out-

side the spray area at Gull Lake, and found to be free of DDT.

PRESENTATION OF DATA

DDT RESIDUES IN SOIL

Samples. - The soil samples analyzed were taken from the
areas shown in figure 2 at depths ranging from 0-6". The
depth of the samples, which were obtained by shovel, was
measured by tape. The soils analyzed consisted of 5-10
composite samples which were thoroughly mixed, placed in
plastic bags, and frozen. Prior to analysis the soils
were thawed, classified as to type, and then air-dried for
24 hours. Ten soil samples were collected on 9 July 1962,
and ten were collected on 7 April 1963. Of the first ten,
five were from open areas, two from under elms, two from
under thick shrubbery, and one from a wooded area. In the
second series two were collected from open areas, three from
under elms, and four from beneath shrubs. Muck from the

lagoon was also collected.

Results and Discussion. - Table 1 shows the amounts of DDT
found in 20 soil samples obtained from the study area. DDT
levels in the soil were low (below 7ug. of DDT/9.). Soil
samples collected in open areas on 9 July 1962 contained
from O-l.67ug. of DDT/g., those beneath elms had 1.62-1.65

ug. of DDT/9., and those under shrubs 2.78-2.79 ug. of DDT/g.

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TABLE 1

DDT FOUND IN SOILS

 

 

NO‘ obE:::ed :Oil source Digth :gT/Of

ype inches g.
8—1 7/9/62 Loam Wooded area 0-2 2.81
S-2 7/9/62 Sandy loam Open area 1—3 0.00
8-3 7/9/62 Sandy loam Under elms 0-1 1.62
8-4 7/9/62 Loam Base of elms 0-1 1.65
S-5 7/9/62 Sandy loam Open area 0—1 0.00
8-6 7/9/62 Loamy sand Open area 0-1 1.15
8-7 7/9/62 Loamy sand Open area 0-1 1.67
8-8 7/9/62 Loamy sand Open area 0—4 0.00
8-9 7/9/62 Loam Under shrubs 0—2 2.78
S—lO 7/9/62 Sandy loam Under shrubs 0-2 2.79
S-ll 4/7/63 Loamy sand Under shrubs 0-1 6.25
S-12 4/7/63 Loam Under shrubs 1-2 1.16
S-13 4/7/63 Loam Under shrubs 4-6 0.00
S-l4 4/7/63' Loamy sand Base of elms 0-1 5.57
8—15 4/7/63 Loam Base of elms 4-6 1.09
S-16 4/7/63 Sandy loam Base of elms 0-1 2.12
8-17 4/7/63 Muck Lagoon 0-3 0.00
S-18 4/7/63 Loamy sand' Open area 0-1 0.00
8—19 4/7/63 Sandy loam Open area 0-1 0.00
s-2o 4/7/63 Gravelly' Under shrubs 1—2 1.15

loamy

sand

 

 

l4

Soils collected on 7 April 1963, nearly a year after spray-
ing,were negative in open areas, contained 1.09-5.57 ug. of
DDT/g. under elms, and O-6.25 ug. of DDT/g. under shrubs.

The results showed that soils in areas receiving the
heaviest spraying (shrubs and elms) had greater quantities
of DDT than soils receiving chiefly drift (open areas).

S-ll contained 6.25 ug. of DDT/g., the highest concen-
tration found in soils, while S-l4, from the base of an elm
was next highest with 5.57 ug. of DDT/g. Both were surface
soils collected at a depth of 0-1". 8-12 contained 1.16 ug.
of DDT/g. and 8-13 was negative. S-12 and S-l3 were obtained
in the same area as S-ll but at different depths, 1-2" and
4-6", respectively. This indicates that most of the DDT
residue was present in the first inch of soil, even 38 weeks
after spraying. Normally soil samples used for analysis con-
sist of core samples to a depth of 6". Ginsburg has shown
that DDT does not penetrate vertically downward beyond a
depth of 6" (Ginsburg _E_§l,, 1954). Since samples in this {
study from 4—6" depths contained very small amounts of DDT, t
it is evident that DDT was retained primarily in the first
inch.

Numerous studies have been made to determine the persist-

ence of DDT in the soil. Foster (1951) has shown that DDT

15

residues in the soil were not affected by soil types or

rain over a period of four years. However, under certain

t al,, 1958).

conditions of high temperature (Lichtenstein
and humidity (Barlow et al., 1956), some DDT decomposition
does occur. Microbial organisms also cause a breakdown of
DDT; 50 per cent wetable DDT powder in low concentrations is
affected the most (Jones, 1952, 1956). Sunlight may decom-
pose DDT, with the rate of decomposition greatest for the
lowest dosage (Ginsburg, 1952, 1953).

S-l9 and 8-18, taken in the same areas as 8-6 and 8-7
respectively, showed a complete loss of DDT 38 weeks after
spraying. Since the entire 32-acre site was sprayed only
once the year this investigation was being conducted, the
effect of repeated applications could not be studied. Re-
peated applications of DDT have been shown to increase the
concentration of DDT in soil (Chisholm, 1955). In this study,
soil at the base of elms was found to increase in DDT over a
period of 35 weeks. Comparison of amounts of DDT found in
8-16 and 8-4, from the base of the same elm, showed this
increase to be 28.5 per cent. Presumably, the increase was
due to run-off from the trunk or decomposition of elm leaves
containing DDT after the leaves fell to the ground. Barker

(1958) has shown that the quantity of DDT in soil does not

16

decrease over winter, but actually increases in some cases
with the fall of sprayed leaves. This may also be the ex-
planation for the higher amounts of DDT found in soil under
shrubs and bushes, where fallen leaves were not removed as

they were in open areas.

DDT RESIDUES IN EARTHWORMS

Samples. - Ten earthworm samples, representing three dif-
ferent species, were collected and analyzed for DDT. Each
sample consisted of 5-10 individuals of Helodrilus with the
exception of W—9, which was a single specimen of Lumbricus

terrestris. During the period of the investigation earth-

 

worms were difficult to find, although robins had little
trouble finding them early in the morning. Most attempts
to find worms during and after rains resulted in failure.

Of the 10 samples analyzed, seven were collected on 20
June 1962 and three on 7 April 1963. Most of the samples,
specimens of the small garden worm (Helodrilus §p,), were
found in a wooded area in moist loamy soil beneath fallen
leaves. Red worms (Helodrilus foetidus) were abundant in a
decaying pile of leaves left from the sanitation and clean-
up program conducted yearly on the grounds. Sites from

which earthworm samples were taken are plotted in figure 3.

17

TABLE 2

DDT FOUND IN EARTHWORMS

 

 

a:
No. obE:::ed Species Source gg&/;f
W-l 6/20/62 Helodrilus s2, Island 8.33
W-2 6/20/62 Helodrilus s2, Wooded area 0.00
W-3 6/20/62 Helodrilus s9, Wooded area 2.75
W-4 6/20/62 Helodrilus s2, Wooded area 12.50
W-5 6/20/62 Helodrilus gp, Wooded area 2.98
W-6 6/20/62 Helodrilus s2, Wooded area 14.00
W-7 6/24/62 Helodrilus sp, Base of elms 6.25
W-8 4/ 7/63 Helodrilus s2, Under shrubs 3.18
W—9 4/ 7/63 Lumbricus terrestris Under shrubs 0.00
W-lO 4/ 7/63 Helodrilus foetidus Leaf litter 3.27

 

 

 

 

 

 

 

 

 

 

 

 

18

Results. - Table 2 presents the results of the analyses of
10 earthworm samples collected at the Kellogg Biological
Station. No attempt was made to determine the levels of DDT
in the intestinal organs. The greatest amount was 14ug. of
DDT/g. in tissue found in W-6 in a wooded area. Samples

W-2 and W—9 from the same area, collected at the same time,
were negative. Samples W-l, W-4, W-5, and W-6, also from
the same wooded area and collected on the same day, had
higher levels of DDT than the soil in which they were found
(compare values to S-l, table 1).

This supports the findings of Barker (1958). Barker
found that earthworms can accumulate DDT and concentrate it
i11 their body tissues by obtaining the residues from sprayed
soil or leaf litter from sprayed trees. Similarly, sample
W-7, obtained near the base of an elm, contained higher lev-
els of DDT than the soil from which it was obtained (see
S—4, table 1).

The results also show that DDT was present in earthworm
tissues not only in summer but also in spring specimens 38
weeks after spraying. Hence, DDT was either retained by the
worms in some measure over winter, or it was reaccumulated

in the spring from contaminated leaf litter or soil.

19

Discussion. — No correlation was made between the three dif-

 

ferent species of earthworms collected and the levels of DDT
they accumulated. It seems unlikely that the quantities of
DDT found in the earthworms analyzed approach the lethal lev—
els necessary tx: cause immediate mortality in robins. The
lethal level of DDT in the brain for adult robins is greater
than 50 ug. of DDT/g. (Bernard, 1963). Earthworms analyzed
from the Michigan State University campus, an area of high
robin mortality, ranged up to 88 ug. of DDT/g. (Bernard,

Ph. D. thesis, 1962). Boykins (pers. comm.) also found
greater than 50 ug. of DDT/g. in campus earthworms analyzed
in 1963. The average concentration found in robins at the
station was 8.6 ug. of DDT/g. in brain tissue (see p. 30).
However, robins consuming numerous earthworms containing
sublethal levels of DDT may actually be concentrating it in
their tissues over long periods of time. This has not been
investigated, but analyses of brains of eight robins fed
DDT-injected earthworms (by J. J. Hickey at the University
of Wisconsin) at a dosage of 110 mg. of DDT/Kg. of body
weight, disclosed the tremoring birds died with greater
than 50 ug. of DDT/g. in the brain (Bernard, 1963). Thus,
earthworms analyzed in this investigation appear to have had

DDT levels sublethal to robins feeding on them. The lethal

20

amount for robins, in earthworms, must be somewhere between
14 and 110 ug. of DDT/g.

Applications of 100 pounds of DDT/acre are ineffective
for the control of the exotic earthworm,(Pherentima spfi

(Fleming t al., 1945), and some earthworms survive at ap-

 

t §_1_. , 1946) .

plications of 214 pounds of DDT/acre (Richards
The lack of abundance of earthworms and the difficulty in
finding them was probably a result of a combination of en-
vironmental factors: low temperature, lack of rain, and
dry soil, rather than of earthworm mortality caused by the

toxicity of DDT.

DDT RESIDUES IN LEAVES, FRUIT, AND ELM BARK

Samples. - A total of 26 samples, primarily leaves, fruit,
and elm bark,were collected and analyzed for DDT residues.
The samples, for the most part, were randomly selected at
three foot heights in areas which had received the heaviest
spraying. In many instances the dried, milky-white residue
of DDT could be seen on the plant surface. The DDT levels

in leaves and fruit of crab apple (Malus coronaria), honey-

 

suckle (Lonicera sp,), and choke cherry (Prunus virginiana)

 

were determined. Leaf samples of juneberry (Amelanchier

canadensis), lilac (Syringa vulgaris), and honey locust

 

Figure

21

 

 

 

 

 

location of Plant and Animal Materiel Collected at the
Kellogg Biological Station, Kelmsoo County, Inchigen

 

 

  

 

 

I
00 w ‘00

Sec-d2. ‘u= 200’

 

22

(Geditsia triacanthos), were collected as were fruits from

mulberry (Morus rubra), sweet cherry (Prunus avium), and

 

ornamental bittersweet (Celastrus obiculata).
Six samples of elm bark from the trunks of elms (Ulmus

americana) were analyzed as well as a sample of leaf mulch,

 

and a composite sample containing 12 camel crickets (Ceu-
thophilus maculatus). Sites of the samples are shown in

figure 3 and listed in table 3.

Results. - The levels of DDT found in leaves, fruit, and
bark were variable, as can be seen in table 3. The highest
concentration of DDT was from a sample of juneberry leaves
collected soon after spraying. The leaves contained the
astonishing level of 1388 pg. of DDT/g. High concentrations
were also found on lilac leaves. A sample collected 20 June
1962, yield 254 ug. of DDT/g., while another sample collected
9 July 1962,from the same bush, had 94.5 ug. of DDT/9., in-
dicating a 62.2 per cent decrease of DDT over a period of 19
days.

Low levels of DDT (4.11 ug. of DDT/g.) were found on
crab apple leaves collected on 8 August 1962. Dried crab
apples found on the ground in another area on 7 April 1963

were negative. Leaves from a honeysuckle obtained 8 August

DDT FOUND IN LEAVES,

23

TABLE 3

FRUIT, AND BARK

 

 

 

No Date Kind of Source ug. of
° obtained plant material DDT/g.
S-l 6/20/62 Mulberry, fruit On ground 4.41
S-2 6/20/62 Mulberry, fruit 1' off ground 3.97
S-3 6/20/62 Mulberry, fruit 2' off ground 1.62
S-4 6/20/62 Mulberry, fruit 3' off ground 1.12
S—5 6/20/62 Mulberry, fruit 5' off ground 0.00
S-6 6/20/62 Mulberry, fruit 8' off ground 0.00
S-7 6/24/62 Juneberry, leaves 2' off ground 1388.00
S-8 6/20/62 Lilac, leaves 3' off ground 254.00
S-9 7/ 9/62 Lilac, leaves 3' off ground 94.50
S-lO 8/ 8/62 Crab apple, leaves 3' off ground 4.11
S-ll 4/ 7/63 Crab apple, fruit Dried, on
ground 0.00
S-12 8/ 8/62 Honeysuckle, leaves 3' off ground 21.10
S-1 4/ 7/63 Honeysuckle, leaves Dried, on
ground 4.80
S-14 8/ 8/62 Honeysuckle, fruit 3' off ground 10.20
S-15 8/ 8/62 Choke cherry, leaves 3' off ground 9.46
S-16 8/ 8/62 Choke cherry, fruit 3' off ground 5.50
S-l7 8/ 8/62 Honeylocust, leaves 3' off ground 52.50
S-18 6/20/62 Sweet cherry, fruit 3' off ground 1.00
S-19 4/ 7/63 Ornamental bitter-
sweet, fruit Dried, on vine 0.00
S—20 8/ 8/62 Elm bark 3' off ground 21.80
S-21 8/ 8/62 Elm bark 3' off ground 111.40
S-22 8/ 8/62 Elm bark 3' off ground 146.40
S-23 4/ 7/63 Elm bark 3' off ground 16.90
S~24 4/ 7/63 Elm bark 3' off ground 5.25
S-25 4/ 7/63 Elm bark 3' off ground 17.50

 

 

24

1962 had 21.1 ug. of DDT/g. A sample of leaf mulch collected
eight months later beneath the same bush had 4.08 ug. of DDT/
g., a 77.2 per cent loss from the original source. Loss of
DDT from the plant surface was not 100 per cent as shown by
the level obtained in the leaf mulch. Prior to its decom-
position, the DDT present in the dried leaves was very prob-
ably incorporated in the soil or became incorporated in soil
organisms such as earthworms.

Generally, the fruits contained lower levels of DDT than
leaves from the same species. Leaves of a choke cherry had
9.46 ug. of DDT/g. while the berries contained 5.5 ug. of
DDT/g. In samples from a honeysuckle the leaves contained
21.1 and the berries 10.2 ug. of DDT/g.

Robins had been observed eating cherries near the or-
chard. A sample of partially eaten cherries disclosed only
1 ug. of DDT/g. Similarly, a sample of fruit of bittersweet,
which cedar waxwings were feeding on,was analyzed and found
negative.

The extreme differences in the amounts of DDT found on
leaves and fruits obtained at the same height probably was
due to the lack of uniformity of the spray application as
well as continued growth of the fruit. Lower levels in the

fruit and a decrease in the amount of DDT found on leaves

25

over a period of eight months could be attributed to weath-
ering, and plant and fruit growth. Taschenberg (1960) has
shown that weathering and plant growth are factors which af-
fect DDT deposits on grapes. Weather causes a loss in the
initial deposit, while growth affects the final level of DDT
found when expressed on a weight-weight basis. The level of
DDT obtained by analysis of a mature fruit would be less
than the level obtained from an immature fruit due to the
increase in size and weight resulting from plant growth,
even though the initial deposits of DDT on the fruit may have
been the same.

Six samples of ripe mulberries, obtained on 20 June 1962
from the same tree at various heights, showed that the con-
centration of DDT was inversely proportional to the height of
the berries from the ground. Those berries collected on the
ground contained the highest levels of DDT - 4.41 ug. of
DDT/g. - while those at five and eight feet were negative.

DDT levels in elm bark were relatively high. Of three
samples collected on 8 August 1962, at three foot heights, one
had 21.8, another 111.4, and another 146.4 ug. of DDT/g.

DDT levels were lower in three samples collected on 7 April
1963; these were 5.25, 16.9, and 17.5 ug. of DDT/g., indi-

cating a general decrease of DDT residue on elm bark over a

26

period of eight months. Comparison between samples S-24 and
S-20 (table 3), obtained from the same tree,shows a 75.9 per
cent decrease, while comparison between S-25 and S-2l, also
from the same tree, indicates a 84.3 per cent decrease.

A sample of camel crickets, not listed in table 3, con-
tained 2.16ug. of DDT/g. in their tissues, indicating the
possibility of insecticidal resistance in this species since

they were collected alive.

Discussion. - DDT was available to many birds as shown by
the residues present in the samples tested. Bark foragers
(woodpeckers, chickadees, nuthatches, and creepers) may have'
obtained high and possibly lethal levels of DDT from insects
in bark crevices. Foliage gleaners (orioles, vireos, and
warblers) could receive low to very high concentrations of
DDT by gleaning leaves for insect prey. Birds feeding on
fruits and berries (cardinals, grosbeaks, waxwings) could
obtain low and probably sublethal levels of DDT. Dried

leaf mulch contained DDT available to wrens and other ground
feeders. Also, insect-feeding birds may have obtained the
poison by feeding on DDT-resistant insects which contained

the toxin in their tissues.

27

The effect of translocation of DDT from the soil to var-
ious parts of the plants was not determined. Most investi-
gations of this sort have been with field crops where the
effects on plants are dependent upon soil type and concentra-
tion of DDT (Lindgreen §p_al,, 1954; Lichtenstein, 1958).
There is no evidence that DDT is translocated in woody plants.
Hence, it was assumed that the results obtained above were
due to the amount of DDT residue present on the plant sur-

face after spray application.

DDT RESIDUES IN EGGS

Samples. - Five unhatched eggs - three robin, one barn swal-
low, and one brown thrasher - were analyzed for DDT. Both

the robin and the barn swallow eggs were laid after the
spraying of 14 June 1962. Prior to analysis the egg shells
were removed to eliminate the possibility that DDT was present

only on the egg surface.

Results and Discussion. - The DDT residue in these eggs is
shown in table 4.

The three robin eggs found 21 June 1962 were from a nest
which was abandoned by the parents. They contained 10.8,

11.3, and 15.2 ug. of DDT/g.

The barn swallow egg.

28

from a nest containing five eggs

found 20 June 1962, was the only egg which did not hatch.

It contained 2.70 ug. of DDT/g.

A brown thrasher egg was found on 6 July 1962, in an
abandoned nest. This egg had 7.85 ug. of DDT/g.
all of the eggs analyzed contained DDT. The

robin eggs contained the highest levels.

in eggs could have been passed on by the parent, and may

have contributed to the failure of the eggs to hatch.

TABLE 4

DDT FOUND IN EGGS

The DDT present

 

 

 

 

 

 

 

N°° obE:::ed SpeCieS SET/3f
E-l 6/20/62 Barn swallow (Hirundo rustica) 2.70
E-2 6/21/62 Robin (Turdus migratorius) 15.20
E-3 6/21/62 Robin (Turdus migratorius) 10.80
E—4 6/21/62 Robin (Turdus migratorius) 11.30
E-5 7/ 6/62 Brown thrasher (Toxostoma rufum) 7.85

 

In the summer previous to this study, Moldenhauer found
15 non-hatching catbird eggs out of 52. Mitchell (1946)
has shown that direct spraying of nests and eggs with high

concentrations of DDT will not affect egg hatch, but

29

exposure of adult pheasants and quail to DDT immediately
prior to the breeding season results in lower egg fertility
and high chick mortality (Dewitt, 1955; Cross §p_a1,, 1962).
Unfortunately, the minimum levels of DDT required to affect
the various stages of development and reproduction have not
been determined.

Of special interest was the finding of DDT in the
barn swallow egg. Published records of insect-eating birds
which feed on the wing having accumulated DDT were not to be
found. Two swifts, a martin, and a nighthawk analyzed by
Bernard (1962) were negative. It seems probable that the
DDT in the barn swallow egg was passed on by the parents

which had fed on DDT—resistant insects.

DDT RESIDUES IN BIRDS

Samples. - Twenty-three birds, representing 11 different
species, were examined for DDT. Of these, 13 were obtained
from the study area, six from the Michigan State University
campus at East Lansing, two from Potterville, and two from
Dearborn. Of the 13 birds obtained from the study area,
eight were found dead, while five were caught in a mist net.
None of the birds captured alive exhibited tremors commonly

associated with hydrocarbon poisoning.

30

In most cases, the brain, breast muscle, and liver of
each bird were analyzed separately. In the nestling barn
swallow, where the individual tissues were too small to

analyze separately, the whole carcass was used.

Results and Discussion. — The results of these analyses
are shown in table 5.

The results show that only three of the birds found
dead had 50 ug. or more of DDT/g. in the brain. All of
the six robins (Turdus migratorius) analyzed (four from
the study area and two from Potterville) had low concen-
trations of DDT in their tissues. The highest level was
in a robin trapped by mist net. The brain contained 22
ug. of DDT/g., higher than in brains of some robins found
dead. The average concentration of DDT found in the brains
of robins was 8.6 ug. of DDT/g. In 1960 three robins from
the study area, trapped by mist net, and analyzed by Ber-
nard (1963) contained low levels of DDT on the brain.

Eight cedar waxwings (Bombycilla cedrorum) averaged

 

20.6 ug. of DDT/g. in the brain. Wallace (1961) suggested
that waxwings accumulate high levels of DDT in the spring
when budding on sprayed elms, but obtain little or no DDT

in fall or winter when their diet consists primarily of fruit.

31

 

 

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33

However, in this study the level of DDT in the brain of a
winter specimen surpassed the level found in the brain of
a spring bird (see table 5).

Other station birds with low levels of DDT in their
tissues were single specimens of the following: yellow-
shafted flicker (Colaptes auratus), catbird (Dumetella
carolinensis) banded in 1960 and trapped by mist net 16
July 1962, house sparrow (Passer domesticus), rose-
breasted grosbeak (Pheucticus ludovicianus), and starling
(Sturnus vulqaris).

The highest levels of DDT in bird tissues were found
in two insect-eating species. An eastern wood pewee
(Contopus virens), banded in 1960 and found dead 16 July
1962, had 134 ug. of DDT/g. in the liver, while a white-
breasted nuthatch (Sitta carolinensis) also found dead had
137 ug. of DDT/g. in the brain. The wood pewee must have
obtained its DDT by feeding on DDT-resistant insects. The
white-breasted nuthatch could have accumulated DDT by for-
aging in the bark crevices of sprayed elms.

The carcass of a nestling barn swallow (Hirundo rustica),
another insect feeder, had low amounts of DDT. It was not
possible to prove that this bird died of effects of DDT

poisoning, but DeWitt (1959) and Mitchell (1953) have shown

34

that young birds are less resistant to DDT than adults

and have a lower chance of fledging when they are exposed
to DDT. The nestling bird, too young to feed itself, may
have had DDT passed on to it by the parent, either through
the egg, or by the adults feeding it DDT-contaminated
insects.

Bernard (1963) has indicated that the minimum lethal
amounts of DDT for tremoring robins and house sparrows are
50 and 65 ug. of DDT/g. in brain, respectively. The liver
served as an organ of storage of DDT, and often had higher
levels of DDT than the brain. However, the results in
this investigation indicated that the brain contained
higher amounts of DDT than liver or breast muscle. This
may have been due to the fact that in birds receiving small
quantities of DDT in their diets,the liver was not forced
to function as a storage organ until a certain level was
reached on the brain. Another reason may have been that
elimination of DDT was greater and faster in the liver than
in the brain when low amounts were ingested. Bernard (1963)
found that birds on a diet of 300 mg. of DDT/Kg. of food
followed by a diet free of DDT, were able to eliminate the

poison from the brain, breast muscle, and liver.

35

Although a few birds contained high levels of DDT in
the brain, most did not. Since the levels of DDT in the
brain were low, and no birds examined were known to have
exhibited tremors, the conclusion is that the dead birds
in this investigation had sublethal levels and did not
die as a result of DDT poisoning. Return of a catbird
and a wood pewee, banded on the research area in 1960,
indicates that they had not accumulated enough DDT prior
to 1961 to cause death during migration. However, banded
returns at the station have been very low, suggesting pos-

sible migration losses from DDT.

GENERAL DISCUSSION AND CONCLUSIONS

Results of soil and earthworm analyses showed that low
levels of DDT were present at the Kellogg Biological Station
in 1962. In some cases earthworms contained greater con-
centrations of DDT than the soils from which they were taken.
DDT persisted in some soil samples, increased in amounts in
soils at bases of elms, and was completely lost in soils
from open areas 38 weeks after spraying.

DDT was found in widely variable amounts, ranging from
0-1388 ug./g. on leaves, 5.25-146.40 ug./g. on elm bark,
and 0—10.2 ug./g. on fruit. The analyses of plant and animal
material indicated that DDT, though present in variable
amounts, was freely accessible to leaf-gleaning, ground-
feeding, bark-foraging, seed-eating, fruit-eating, and
insect—feeding birds.

The results of plant analyses also showed that greatest
loss of DDT from the plant surface occurred during the first
month after spraying. Losses of DDT from trunks of elms
ranged from 75.9 to 84.35 per cent. Low concentrations of
DDT persisted in dried leaf mulch.

DDT found in unhatched eggs and young birds never having

been exposed to DDT indicated the probability that DDT was

36

37

passed directly from the female to the eggs and young.

All but one of 23 birds analyzed had DDT in their tis-
sues. All birds (13) from the study area contained DDT.
Analyses of individual tissues, such as brain, breast mus-
cle, and liver, showed that variations in concentrations
of DDT existed in these tissues from different specimens.
These variations may have been due to the rate of accumu-
lation or the ability to avoid ingesting lethal amounts
in their food.

Generally, the brain contained higher levels of DDT
than liver or breast muscle. Of 19 birds found dead only
three had 50 pg. or more of DDT/g. in the brain. Some
birds live—trapped by mist net contained higher levels of
DDT in their tissues than birds of the same species found
dead. None of the live birds showed the symptoms commonly
associated with hydrocarbon poisoning; tremoring,of course,
could not be ascertained in birds found dead.

Because of the absence of birds in tremors, and the
low concentrations of DDT present in the tissues of dead
birds, it seems evident that most of the birds analyzed
in this study did not die as a direct result of the ingested
toxicant. Only the nuthatch and pewee had lethal or near

lethal levels in the brain, 137 ug. and 43,7 ug. of DDT/g.

38

respectively. High bird populations in the study area were
attributed to the fact that the birds were not exposed to
lethal levels of DDT. However, this investigation has also
shown that repeated applications of 0.125 pounds of DDT/acre
resulted in variable amounts of DDT in plant and animal tis-
sues, and that even at this low dosage, high concentrations

were available to leaf—gleaning and bark-foraging birds.

S UMMARY

A DDT spray program in effect since 1954 at the W. K.
Kellogg Gull Lake Biological Station, Kalamazoo County,
Michigan, has been accompanied by high bird populations
and apparent lack of any unusual bird mortality.

This investigation was undertaken during the summer of
1962 in an attempt to discover, under actual field con-
ditions,the reasons for the apparent lack of mortality.
The methods used included analyses of samples of plant
and animal material to determine their content of DDT,
its persistence, and its availability to birds. Levels
of DDT in eggs, young, and adult birds were determined.
Analysis for DDT was by the Schechter—Haller method.
The effect of Chlordane upon analytical values for DDT
was determined. Results showed that Chlordane, even
in high concentrations, did not affect the determina-
tion of DDT beyond the normal limits of reproducability
with the procedure.

Results of soil analyses showed that DDT levels were
below 7 ug. of DDT/g. Soils at the base of elm trees
and from under shrubs had higher levels of DDT than did

soils from open areas.

39

10.

11.

4O

DDT levels were greater in soils obtained at 0-1"
depths than at 4-6".

Thirty—nine weeks after spraying, DDT was completely
lost from soils in open areas, but persisted in soils
under shrubs. Alsq soils at the base of some elms
contained more DDT (28.5 per cent more) 38 weeks after
spraying than found in samples obtained soon after
spraying.

Analyses of earthworms showed that DDT in levels below
15 ug. of DDT/g. was present in their tissues during
spring and summer. Results also showed that earth-
worms often contained higher levels of DDT than did the
soils from which they were taken.

The amounts of DDT found on leaves, fruit and elm bark
varied greatly. Leaves contained levels of DDT ranging
from 0-1388 ug.; elm bark, 5.25-146.4 ug.; and fruit,
0—10.2 ug. of DDT/g.

Fruits contained lower levels of DDT than did leaves
from the same plant. The concentration of DDT in fruits
analyzed varied inversely with the height of the fruit
from the ground.

Live camel crickets contained 2.16 ug. of DDT/g. in
their tissues indicating the possiblity of some DDT

resistance in this species.

12.

13.

14.

15.

16.

17.

41

DDT decreased 62.2 per cent from the surface of leaves
of plants tested over a period of 19 days; 77.2 per
cent loss occurred after eight months. Losses of DDT
from trunks of elms ranged from 75.9 per cent to 84.3
per cent over eight months. DDT persisted in dried
leaf mulch in low concentrations.

Analyses of unhatched bird eggs showed concentrations
of DDT which ranged from 2.75 to 15.2 ug. of DDT/g.

Of 23 birds, representing 11 different species that
were analyzed, all except one had DDT. None of the
birds exhibited tremors. Generally the brain contained
higher levels of DDT than did liver or breast muscle.
Only three of the 17 dead birds analyzed had 50 or
more ug. of DDT/g. in the brain. The average concen-
tration of DDT found in brains of six robins was 8.6
ug. of DDT/g.

The average concentration of DDT found in brains of
eight cedar waxwings obtained from outside the study
area was 20.6 ug. of DDT/g. In one instance the level
of DDT in the brain of a bird that died in winter sur-
passed the level found in a dead spring bird.

A catbird and eastern wood pewee, banded in 1960 and

retrapped by mist net in 1962, had levels below 44 ug.

18.

19.

20.

42

of DDT/g. in the brain.

The carcass of a nestling barn swallow contained low
amounts of DDT.

The results support the conclusion that birds exposed
to the varied and widely available concentrations of
DDT in the study area accumulated variable levels of
DDT in their tissues through their normal feeding
habits.

Finally, this investigation showed that the dead birds
analyzed in this study did not die as a direct result
of ingestion of the toxicant, and that apparent lack
of bird mortality due to spray treatments in the study
area was attributable to the sublethal levels of DDT

accumulated in their tissues.

LITERATURE CITED

Adams, L., M. B. Hanavan, N. W. Hosley, and D. W. Johnston.
1949. The Effects on Fish, Birds, and Mammals of DDT
used in the control of Forest Insects in Idaho and Wy—
oming. Jour. Wildl. qut. 13; 245-254.

Association of Official Agricultural Chemists. 1955. Off.
Meth. of Anal.‘ 8th edition :406—415.

Ball, R. C. and L. L. Curry. 1956. Culture and Agricul-
tural Importance of Earthworms. Mich. State Univ. Ag.
Exp. Sta-Coop. Ext. Svc. Circ. Bull. 222. 5 pp.

Barker, R. J. 1958. Notes on some Ecological Effects of
DDT Sprayed on Elms. Jour. Wildl. Mgt, 22; 259-274.

 

Barlow, F. and A. B. Hadaway. 1956. Effect of Changes in
Humidity on the Toxicity and Distribution of Insecti-
cides Sorbed by Some Dried Soils. Nature (London).
118; 1299-1300.

Bernard, R. F. 1962. Ph.D. Thesis — Field and Laboratory
Studies on the Effects of DDT on Birds. Michigan State
University. 88 pp.

. 1963. Studies on the Effects of DDT on Birds.
Mus. Publ. Mich. State Univ. Biol. Series. Vol. 2:
No. 3. 31 pp.

Chisholm, D., A. W. MacPhee and C. R. MacEachern. 1955.
Effects Of Repeated Applications of Pesticides to Soil.
Canad. Jour. Sci. 35: 433—4390

Couch, L. K. 1946. Effects of DDT on Wildlife in a Missis-
sippi River Bottom Woodland. Trans 11th N. Amer. Wildl.
Conf. 323-329.

Cross, D. L., H. L. King, and D. L. Haynes. 1962. The
Effects of DDT in the Diet of the Japanese Quail.
Quarterly Bull. Mich. Agr. Exp. Sta. M. S. U., E.
Lansing. 445 688-696.

De Witt, J. B. 1955. Effects of Chlorinated Hydrocarbons

and Insecticides Upon Quail and Pheasants. Jour. Agr.
Food Chem. 3: 672-676.

43

44

, and J. L. George. 1959. Effects of Chlorinated
Hydrocarbons on Egg Production, Fertility, and Hatch-
ability of Eggs in Pheasants. U. S. Dept. of Int. Fish
and Wildl. Svc., Bureau of Sport Fisheries and Wildlife.
Circ. 85: 32 pp.

Erickson, A. B. 1947. Effects of DDT Mosquito Larviciding
on Wildlife. Pt II. Effects of Routine Airplane Lar-
viciding on Bird and Mammal Populations. Public Health
Reports. pg; 1254—1262.

 

Fleming, J. and D. Hadley. 1945. Effects of DDT for the
Control of the Exotic Earthworm Pherentima pp, Jour.
Econ. Ent. 38; 411.

 

 

Foster, A. C. 1951. Some Plant Responses to Certain In-
secticides in the Soil. U. S. Dept. Agri. Circ. 862.

41 pp.

George, J. L. 1957. The Pesticide Problem. A Brief Re-
view of Present Knowledge and Suggestions for Action.
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