Influence of temperature on effectiveness of lead arsenate against larvae of the Japanese beetle in the soil

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Material Information

Title:
Influence of temperature on effectiveness of lead arsenate against larvae of the Japanese beetle in the soil
Physical Description:
11, 12 p. : ill. ; 27 cm.
Language:
English
Creator:
Fleming, Walter E ( Walter Ernest ), 1899-
Maines, Warren W., 1911-
United States -- Bureau of Entomology and Plant Quarantine
Publisher:
U.S. Dept. of Agriculture, Agricultural Research Administration, Bureau of Entomology and Plant Quarantine
Place of Publication:
Washington, D.C.
Publication Date:

Subjects

Subjects / Keywords:
Japanese beetle -- Larvae -- Control   ( lcsh )
Soil pesticides   ( lcsh )
Lead arsenate   ( lcsh )
Soils -- Effect of temperature on   ( lcsh )
Genre:
bibliography   ( marcgt )
federal government publication   ( marcgt )
non-fiction   ( marcgt )

Notes

Bibliography:
Includes bibliographical references (p. 11).
General Note:
Caption title.
General Note:
"E-622."
General Note:
"July 1944."
Statement of Responsibility:
by Walter E. Fleming and Warren W. Maines.

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 030289010
oclc - 779844236
System ID:
AA00025102:00001

Full Text

LIBRARY
STATE PLANT BOARD

July 19U 3- 622

United States Department of A1 'ioulture
Agricultural Research Administration
Bureau of Entomology and Plant Quarantine



INDMENGB OF TETIPRATMH ON EFFECTIVESS3 OF LEAD
ARSMATZ AGAINST LARVAE OF THE JAPANE3
BYETLZ IN THE SOIL

By Walter E. Fleming, Entomologist, and Warren W. 4aines,
Scientific Aide, Division of Fruit Insect Investigations


INTRODUCTION

Since 1922, when it was discovered that the introduction of
lead arsenate into soil would kill larvae of the Japanese beetle,
Popillia Japonioa Newan (29. A),/ applications of this material
have been used successfully in controlling larvae of this and allied
species. The larvae ingest the arsenical as they burrow through the
poisoned soil or while feeding on rootlets growing in tha soil.

The insecticidal action of lead arsenate in the soil is complex,
being modified by interacting physical, chemical, and biological
factors. The physical condition of the soil, the presence or absence
of various constituents in the soil, the temperature, the moisture,
and the type of vegetation have an effect on the distribution and the
fixation of the chemical and on the activity of the insect. To be
effective, the poison must be distributed in an active form in the
layer of soil in which the larvae are burrowing or feeding. Any
factor which modifies the availability or distribution of the poison
or changes the activity or depth of the larvae in the soil has a
bearing on the success of the treatment.

It has been recognized for several years that the temperature
of the soil was an important factor, but until recently the relation
between temperature and insecticidal action had not been definitely
established. Experiments conducted since 1941 have established this
relationship with the newly hatched and third-instar larvae.


t Underscored figures in parentheses refer to Literature Cited, p.11.







-2-


EFFECTIVNSS OF LEAD ARSEATE AT DIFFERENT T MEMRATURES

In their natural habitat in the field the larvae are subjected to
daily and seasonal variations in the temperature of the soil. Under
such conditions it is difficult to establish definitely the exact rela-
tionship between the temperature and the poisoning. Experiments on
the effect of temperature were therefore conducted in the laboratory
as well as in the field.

In the laboratory experiments at constant temperatures, the lead
arsenate was thoroughly mixed with sifted sassafras sandy loam at the
rates of 20.8 and 41.6 grams per cubic foot, which was equivalent to
incorporating, respectively, 500 and 1,000 pounds of the chemical with
the upper 3 inches of an acre of soil. The soil and the chemical were
mixed by passing them several times through a gyratory riddle. The
treated soil was placed in trays and brought to optimum moisture, and
grass seed was sown. The trays used for newly hatched larvae were
12 inches square and 2 inches deep; those used for third instars were
18 inches square and 3-3/4 inches deep. Each experimental unit con-
sisted of two or more trays of unpoisoned soil and two or more trays
of each arsenical treatment.

Experimental units were placed in chambers and maintained, with a
variation of 1 degree, at 50, 60, 70, and 80 F. during the course
of the investigation. A few days after an experimental unit had been
put into the chamber, 200 newly hatched larvae or 200 to 400 field-
collected third instars were introduced into each tray of untreated and
treated soil. The newly hatched larvae were 2 days old when introduced
into the soil; the age of the third instars at the beginning of the
experiments was unknown, but it was evident that there was some varia-
tion in the degree of development of the individuals. Experiments
certainly could have been conducted more precisely with individuals of
a known age, but it was not possible to obtain a sufficient number of
third instars of known age for this work.

At intervals which varied with the temperature, the larvae were
removed from the soil and a record was made of the number of dead and
living individuals in each tray. The living larvae were then returned
to the soil and each tray was reseeded and watered. The experiments
were repeated several times with different batches of larvae, a total
of 4,800 newly hatched larvae and 7,800 third instars being used in
this phase of the investigation.







-3-


The mortality of larvae in soil containing lead arsenate, s
the result of poisoning and, to some extent, other actors su as
bacterial disease, nematodes, and injury. As the mortality in t-rh
untreated soil rarely exceeded 20 percent even in erperimnts df
long duration, it was evident that death from causes other than
poisoning was not an important factor in this investigation. The
percentage of larvae poisoned by each treatment was determined by
the formula

Number alive in Number alive in
Percent poisoned S untreated soil treated soil 1 -0
Number alive in untreated soil

Scatter diagrams showing the relationship betwe. th : ;..r -.Ii,
of newly hatched and third-instar larvae end the number of .&aye t-'
insects had been in the treated soil were prepared for the 500- and
1,000-pound treatments at each temperature. Then, following the
method outlined by Ezekiel (1), free-hand curves (figs. 1 and 2)
were fitted to the average points.

The difference between each experimentally determined mortality
and the mortality estimated from the average curve was determined.
From these deviations the average standard deviation was found to be
3.3 percent and 3.7 percent for the 500- and the 1,000-pound treat-
ments, respectively, against the newly hatched larvae and 13.9 and
12.5 percent, respectively, for these treatments against the third
instars. The individual experimental results were not entered on
these graphs because of their large number. The average standard
deviations, indicated as standard errors on the graphs, will give
the reader a clue as to how these values were scattered about the
average curves.

It was evident that the effectiveness of the arsenical treat-
ments against both ages of larvae was modified profoundly by the
temperature. With the newly hatched larvae the 500-pound treatment
required about 13 days at 50 F. to kill half of the larvae, 8 days
at 60 F., and 6 days at 70 F. The 1,000-pound treatment accom-
plished this in 11 days at 500 F., 6 days at 60 F., and 4 days at
70 F. The third Instars were considerably more resistant to
poisoning. To kill half the third instars with the 500-pound treat-
ment required more than 160 days at 50 F., 57 days at 60 F., 35
days at 70 F., and 25 days at 80 F.; with the 1,000-pound treatment,
45 days were required at 50 F., 23 days at 60 F., 15 days at 70 F.,
and 11 days at 80 F.







-4-


_tA K 1 jocrCIY OF POISONING AT DIFFXRMT TifRp'e

.... .to be a defiilte relatioAship be wx.'i i-*
.- .s jlty of poisoning with a given tret&.,' -" l a t
A, .- io6ipica of the time :*,ired to obtaia a .'-i.. ts level of
AO- Isif i r a '.?iieiat f y *:;4f 'e ralative vAiCt-';Ujy of poisoning,
fC data deraavav
F tha ave6reA curves givan in figures 1 and 2, the number of days
_. ;-s to 0 Ip -ta axy required percentage of the larvae could be deter-
uid 'A the ei- & e of values in multiples of 10 were obtair.ed
&"d for each Ilel of polsoniuig the i'eiprooals were plotted 6A-iuft i1.0
,i!.t-ooj..-.^ *a < .;.. t^Ki te-Iiiu'rt-o A' stx-aight-line rqlattoikill; 6B a-Nfc-a '<*" .1,1it
btt3 Lwo .a ir .tiv, el o oity v, poiasoniag and the tmpo.-.iS.T The
wiopes i.JAlines were deterained by the method of least aquad eao
It was f ,u tha th& curves for the newly hatched larvae intersected
I. X L. I ,.tse &.Daging froil 38 to 42 F. &ad the ur-ves for the
h ,'.-... .,=-ca 350 and 4107. 'ua& aiveO'a poiut of iitersaotlon in
bALh -b3 Wi .'1it ly 400. As theee variation ioy- be attributed
t,:, 6.- i'd 'i ..Obraiaing the slopbo of these lines, it was aeooided to
.,,..,di.- thr 431e.pa aliihtly so that ohey would intersect the axis at 4O0.
'fi'L tkibo l _ei3iMni, the relhtie velocity of poisoiag of the -larvae
>A-j i :-, ,.:', t.udwt diagramati&ally in figures 3 and 4.

i-!:otijs clr both thu firtt and third inatars
,._, ^....-. .....t e nwith Lti iuCAetiI in the tomparcturs. On tue
., ...I .-.i ?o ',, velocity of poaoninlg was double that at 50, at
,/'. it &II 'A I el at 80 it *ae qiadruipled. The rate of poisoning
of b& I.$j .tho first Instare vdud about four timesi that of the fully


.**1 ~itA-iOLID 1 *ik^nA'lOS OF POl`' l.^MIM

.. --,-i.,,.-praiture at whiL.h la-vae, are oufficlantly active to
.1,ad ari.,utie is an impoxtaut factor in that it limits the period
.ib .|bLidicid action in the fall and in the spring. The threshold
.- .,<--. U4 siu", Nhich the larvae begin to ingest perceptible amounts
Sf I]. -- ,$ t bta determined experimentally. Ludwig (5) considered
,F., Fo as l-.L, the threshold of development of the larvae, and Fox (2)
St-tied .bat 5rv-ae were inactive below this temperature. However,
i-jut, it wa tsitble to poison an appreciable number of newly hatched
,id thir,-iiber latzae at a constant temperature of 500 F., it was
nviiaeit that the threshold of feeding and possibly of movement is below
L ti a ip -.. ,.I

It y o L6e _.uosible to dut.ei zine experimentally the temperature
.1. ,,, ,.,..n; will be perceptible, but it is possible from the
S...)u giveu in figure 3 and 4 to obtain an empirical estimate
of iI *:...:.'tu' The fact that the curves intersected the X axia
at .^.i.. -j'fitely 40 F. suggests that this is about the temperature above
I v.t... are poisoned by lead arsenate in the soil. This temperature
a., -.p teitatively as the threshold of poisoning of larvae
o-f Vile ,.{jV :'., lU,-etle by lead a-aieDste.







-5-


POISONING AND HERMAL SUMMATION

With the close relationship prevailing between the mortality
end temperature, it seemed that the same relationship should exist
between the mortality and the summation of the day-degree unite
above the threshold of poisoning. With 40 F. as the threshold, it
was found with the 500- and the 1,000-pound treatments at constant
temperatures that the products of the number of days and the number
of degrees above the threshold were practically constant values for
each level of poisoning. It was evident that the poisoning was
closely correlated with the summation of the day-degree units above
400.

The mortalities of newly hatched and third-linstar larvae
obtained with the 500- and the 1,000-pound t-oeatments at constant
temperatures were plotted against the summations of the day-degree
units above the threshold. The scatter dlagrams showing this rela-
tionship are presented in figures 5 and 6. The average curves and
their standard deviations were derived in the same manner as those
shown in figures 1 and 2. In this ease the average standard devi-
ation is expressed as broken lines above and below each curve. It
was found that within the range of normal experimental error these
curves were an adequate expression of this relationship.

It was not possible to conduct experiments with newly hatched
larvae in the field, but such experiments were conducted with third
instars. In October 1941 a group of 270 trays of established turf
growing on unpoisoned soil and on soil containing 500 and 1,000
pounds of lead arsenate per acre were infested with 5,400 third
Instars. These trays, which were 18 inches square and about 4 inches
deep, were exposed on the ground to the weather during the course
of the experiment. A record was made daily of the temperature of
the soil at a depth of 1 inch. At intervals of 2, 4, 8, 12, 16, 20,
24, 28, and 30 weeks following the introduction of the larvae, 10
trays of each treatment and 10 trays of unpoisoned soil were removed
to the laboratory and examined to determine the percent of the
larvae poisoned at each time interval.

The mortalities obtained with the 500- and the 1,000-pol'd
treatments during the fall, winter, and spring under variable conditions
in the field at Moorestown, N. J., were plotted against the summations
of the thermal united. The scatter diagrams of this relationship are
shown in figure 6 by open circles. It was evident that these meager
data wre not sufficient to establish the shape of any curves, but
it was found in both cases that two-thirds of the values were within
the limits of the standard errors of the constant-temperature curves.
This suggests that a curve derived from data obtained in the field
would be within the limits of error of a curve derived under controlled
conditions. Since there was no evidence of a difference between these
eurves derived under constant and variable temperatures, it may be
ssumed properly that the curves derived under controlled conditions
would be an adequate expression of the relationship with variable
tiperatures in the field.










-,z a st 1y of the data it may be assumed that the level of
1'iurtai.. obtlinOed with a trea'tiient was dependent upon the number of
_- ..ee units aucc-Tu'la'ited, whether under controlled conditions ia
the lab.1atory or under variable conditions in the field.

JOINT TOTIONAL RELATION OF POISONING OF LARVAE TO CONCFMTRATION
OF LEAD AR '.T.ATT AND ACCUMULATED THRMALJ UNITS

T-iM poi.oning of larvae i s the 9oil is a joint function of the
of tive laa- arsenate in the soil and the accumulated thermal
unLits. It was desired to aeteriiale the extent to which the degree of
poisoning varied with the joint effect of these factors.

As data were available with the newly hatched larvae on only the
500- and the 1,000-pound treatments, it was not possible to establish
this relation for all concentrations of lead arsenate up to 1,000 pounds
per acre. Tuie joint functional relation with the 500- and the 1,000-
pouiid t.nLciieuts was determined according to the procedure outlined
by Ezekiel (1). The average percentages of the newly hatched larvae
poisoned by these treatments with accumulated day-degree units ranging
from 50 to 600 are presented graphically in figure 7.

With the third instarse data based on over 20,000 individuals were
available on lead arsenate treatments ranging by hundreds from 100 to
1,C000 pou,,ds per acre. The joint functional relation was determined with
these trea+-ents, and the average mortalities obtained with accumulated
thermal units ranging from 100 to 1,600 are given in figure 8.

It is evident from figure 7 that a mortality approaching 100 per-
cent of the newly hatched larvae was obtained with the 500-pound treat-
ment and 450 thermal units, and with the 1,000-pound treatment and 300
thenrmal units. In these experiments more than 600 thermal units seemed
to be required before the average first instar in untreated soil was
ready to change into a second instar. Ludwig (6, p. 437, 438) found
the average first instar stadium was 16.7 days at 25 C. and 29.6 days
at 20 C. From these data it was estimated that 618 to 829 thermal
units would be required for the completion of the first stadium. It Is
evident, therefore, that a larva emerging from an egg in soil containing
500 to 1,000 pounds of lead arsenate per acre should die before its
first molt.

With the third instars, as shown in figure 8, high mortality did
not occur at any temperature with concentrations of lead arsenate of less
thun 500 pounds per acre, nor with any of the quantities of lead arsenate
used, if the accumulated thermal units were less than 600. A mortality
of more than 90 percent was obtained with the 700-pound treatment and
1,600 thermal units, with the 800-pound treatment and 1,400 thermal units,
with the 900-pound treatment and 1,200 thermal units, and with the 1,000-
pound treatment and 1,100 thermal units. In these experiments some of
the third instars ceased feeding and began to pass into the prepupal
stage when the accumulated thermal units reached 1,600; many of them were
in the prepupal stage when the accumulated thermal units amounted to 2,000*









This suggests approximately 2,000 day-degree units are required for
the average third instar to complete that instar and pass into the
prepupal stage. Ludwig (6, p. 437, 438) found 101.5 days were re-
quired at 25 C. and 105 days at 20 C. to complete the third Instar
and prepupal stages. From these data it was estimated that 2,940 to
3,755 thermal units would be required.

It would be expected that many of the third instars in treated
soil would transform into pupae and emerge as adults when the con-
centration of lead arsenate in the soil is insufficient to cause a
high mortality with 2,000 thermal units, or when the treatment is
applied after many of the larvae have passed through a considerable
part of their third-instar development.

IXPBOTD 3EF7OTIVICSS OF TREATMIS IN THB EAST

Most of the treatments with lead arsenate for the control of the
Japanese beetle in the soil have been carried on in New Jersey, east-
ern Pennsylvania, southern New York, end Connecticut--areas in whioh
the climatic conditions are comparable. No experiments have been
conducted in northern or southern areas where the climatic conditions
are different from those of this region, but wherever the condition
of the soil is favorable a prediction may be made of the possible
effectiveness of a treatment from the temperature records of the
locality and the data obtained in this investigation. These estimates
for points remote from those where the studies were made are empirical
at present because of the meagerness of the biological and insecticidal
data.

Within th- .. longest infested the first instar is the dominant
larval fo- .dlasummer; the second instar is dominant in late sumer,
And the .Ai-a instars are the most abundant in the fall, winter, and
spring. The third Instars complete their growth and pass into the
prlpupal and pupal stages in the late spring and summer. In the
extreme southern areas where it is possible that there may be two
gsnoeatlons annually and in the extreme northern areas where it is
possible that 2 years may be necessary for the insect to complete its
cycle, all instars may occur In the soil during most of the year, with
no one dominant at any period. It is not possible to consider this
complexity of the larval population in this study. It was assumed
in making the estimates-of the effectiveness of the treatments that
the larval population was not so complex and variable but that in the
central and northern areas first and second instars occurred during
the summer and third instars during the fall, winter, and spring.
In the extreme southern area it was assumed that first and second
Lustars occurred in the summer and winter and third inL' .a in the
spring and fall.

The Initial dosage of lead arsenate is most effective when
applied so that the chemical is in the soil at the time the eggs are
hatching, because newly hatched larvae are the most susceptible to
poisoning, and the temperature of the soil during the summer is the
most conducive to successful treatment. When applied in the fall







-8-


or spring, the effectiveness of the treatment is reduced by the lower
temperature and the greater maturity of the larvae. When the tempera-
ture Ie conducive to successful treatment, there is a good possibility
of killing a larva that ingests the poison shortly after completing its
second molt, but there is practically no possibility of killing a fully
growi third instar that is about to cease feeding and pass into the
preppal stage. It was assumed, for the purpose of this study, that
all the larvae completed their second molt on October 1, so approxi-
mately 2,000 thermal units would be needed from this date before they
would pass into the prepupal stage. In the central and northern areas
these larvae would be partly grown by March 1 and reach maturity somae-
time after the middle of May, but in the extreme southern area it would
be expeoiced that these larvae would reach maturity during the late fall
or early winter. In the latter area where two broods a year may be
anticipated, it was assumed that the second brood would complete its
second molt on March 1.

Data on the temperature of the soil are very limited, but there ie
an abundance of information on the temperature of the air at various
localities throughout the Eastern States.* At Moorestown, N. 1., it has
been found that when the ground is not covered with snow there is little
difference between the average temperature of the air and that of the
soil at a depth of 1 inch. In view of the very high correlation between
these temperatures, it appeared that a close approximation of the sum-
mation of the soil temperatures for the various localities nould be
obtained by a summation of the air temperatures.

Based on the 4ata given in the Yearbook of Agriculture for 1941
(7), the eastern pert of the United States was divided into zones of
equal temperature for the warmest and the coldest periods of the year,
namely, July and January. These zones are shown in figures 9 and 10.
For the warm period, suumations were made of the thermal units at
several localities in each zone for the periods between August 16 and
October 1, September 1 and October 1, and September 16 and October 1.
These summations were corrected for the deviation of the average tem-
perature of the localities in July from the mean temperature ui the zone
:. r that month. For the cold period, summations were made in t-he same
Mwjoicr for each zone during the period from October 1 to May 20 and
from March 1 to May 20.

It was assumed that treatments of 500 and 1,000 pounds of lead
arsenate per acre had been applied by July 1 at several localities in
each of the five summer-temperature zones to destroy the newly hatched
larvae. From the summations of the thermal units in these zones, esti-
mates were made of the expected mortality of larvae on October 1 from
batches of eggs hatched on August 16, September 1, and September 16.
These expected mortalities are given in figure U1.

It was assumed, further, that the control agents in some localities
were unable to apply the treatment on July 1, but some of them applied
treatments on October 1 and others on March 1, with dosages ranging from
200 to 1,000 pounds per acre. From the summations of the thermal units







-9-


in the nine winter zones, estimates were made of the expected
mortality of the third instars by May 20 from these treatments.
The expected mortalities are given iL figure 12.

In those lo-.alities where treatments were applied before the
eggs hatched, it would be expected that all larvae hatching on or
before August 16 thrcugr)ut the eastern part of the United States
would be killed by applications of 500 pounds of lead arsenate per
acre. Of the batch hatching on September 1 it would be expected
that all the larvae would be poiaconed by the 500-pound treatment
in summer zones 3, 4, and 5 and with the 1,000-pound treatments
also in summer zones 1 and 2. All the larvae that hatched on
September 16 in zone 5 would be expected to be killed by the 500-
pound treatment and by the 1,000-pound treatment in zones 4 and 5.
The mortality caused by the latter treatment would be expected to
approach 100 percent in suiner zones 2 arnd 3 by October 1, but
complete mortality would not be expected by this date. In zone 1
a mortality of 68 percent would be expected with the 500-pound
treatment and 83 percent with the 1,000-pound treatment. However,
the probabilities are that those newly hatched larvae still alive
in treated soil on October 1 would ingest a lethal dose of the
poison before completing their growth.

In those localities where treatment was delayed until October 1,
it would be expected that practically complete elimination of the
third instars would be obtained with the 500-pound treatment in
winter zones 5, 6, 7, 8, and 9, with the 800-pound treatment in
zone 4, and with the 1,000-pound treatment also in zone 3. It would
be expected that the 1,000-pound treatment would poison 84 percent
of the third instars in the soil in zone 2 and 58 percent of them
in zone 1.

In those localities where treatment was delayed until March 1,
practically complete elimination of the third instars would be
expected with the 500-pound treatment in winter zone 9, with the
800-pound treatment in zones 7, 8, and 9, and with the 1,000-pound
treatment also in zone 6. With the 1,000-pound treatment a reduc-
tion of at least 75 percent could be expected in zone 4, a 50 per-
cent reduction in zone 3, and something less than 50 percent in
zone 2.

Thus from a consideration of the temperatures in the eastern
part of the country, between the Greet Lakes and the Gulf of Mexico
and from the Atlantic coast to the Plains, it is anticipated that
if the treatment is adjusted to compensate for the differences in
soils and if the application is timed so that the poison is distrib-
uted in the soil at the time the eggs are hatching, practically
complete elimination of the larval population can be obtained with
the 500-pound treatment of lead arsenate. When the treatment is
not timed for the newly hatched larvae but applied when the larvae
have developed to the last Instar, variable results must be expected
on the current population throughout this region.








- 10 -


SUMMARY

Since 1941 an investigation has been conducted to establish the
influence of the temperature of the soil on the effectiveness of lead
arsenate against the larvae of the Japanese beetle. In the maze of
interacting factors influencing the insecticidal effect, the tempera-
ture was found to be one of the most important.

The velocity of poisoning of the first and third instars increased
progressively with the increment in the temperature. At 60 F. the
velocity was double that at 50, it was tripled at 70, and quadrupled
at 80. The rate of poisoning of the newly hatched larva was about
four times that of the fully grown third instar.

A temperature of 40 F. appeared to be the empirical threshold
above which poisoning of the larvae by lead arsenate became perceptible.

The poisoning of the larvae was correlated with the summation of
the day-degree thermal units above this threshold. This relationship
prevailed with constant temperatures in the laboratory and to a consid-
erable degree with variable temperatures in the field.

The joint functional relation of the poisoning of the larvae to
the concentration of lead arsenate in the soil and the accumulated
thermal units was determined. Newly hatched larvae in soil containing
500 pounds of lead arsenate per acre would be expected to be poisoned
before the first molt. Third instars can be expected to cease feeding
and pass into the prepupal stage when the accumulated thermal units
from the last molt reach 2,000. The effectiveness of the poison
against this instar is dependent upon the amount of lead arsenate
applied and the number of thermal units accumulated after the distri-
bution of the chemical in the soil.

Consideration was given to the temperatures in the eastern part
of the United States, between the Great Lakes and the Gulf of Mexico
and from the Atlantic coast to the Plains. It is anticipated that
when the treatment is adjusted to compensate for the differences in
soil, and the application is timed so that the poison is distributed
in the soil at the time the eggs are hatching, practically complete
elimination of the larval population can be obtained with 500 pounds
of lead arsenate per acre. When the treatment is not timed for the
newly hatched larvae but applied when the larvae have developed to
the last instar, variable results can be expected on the current
population throughout this region.







- 11 -


LITERATURE CITED


(1) Ezekiel, M.
1930. Methods of correlation analysis. 427 pp., illus.
New York.

(2) Fox, H.
1935. Some misconceptions regarding the effects of the
cold of February 1934 on the larvae of the Japanese beetle,
Popillia Japonioa Nwman. Jour. Boon. Rat. 28: 154-159.

(3) Leach, B. R.
1926. Experiments with certain arsenates aa &oil ib a.6tiCeJmg.
Jour. Agr. Rea. 33: 1-8.

(4) ----- leming, W. B., and JTohnson, J. P.
1924. Soil insecticide investigations at the Japanese
beetle laboratory during 1923. Jour. Ioon. Ent. 17: 361-365.

(5) Ludwig, D.
1928. Development of oold hardiness in the larvae of the
Japanese beetle (Popillia Japonioa Nomn.). Zoology 9: 303-306,
illus.

(6) ---------
1932. The effect of temperature on the growth curves of
the Japanese beetle (Popillia Japonica Neman). Physiol.
Zool. 5: 431-"7, illum.

(7) Rossby, C. G.
1941. The scientific basis of modern meteorology. U. S. Dept.
Agr. Yearbook (Climate and Man) 1941: 599-655, illus.




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I


ure 1.- Effectiveness of the 500- and the 1,000-pound treatments
ith lead arsenate against newly hatched larvae of the Japanese
eetle at constant temperatures of 60, 600, and 70 F.


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PERCENrT POISONED
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Figure 2.- Effectiveness of the 500- and the 1,000-pound treatments
with lead arsenate against third instars of the Japanese beetle at
constant temperatures of 50, 60, 70, and 80 F.











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o 6 500 a 60
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50" 40 50" 60" 7C2

TEMPERATURE
Figure 3.- Relative velocity of poisoning
of newly hatched larvae of the Japanese
beetle with the 1,000-pounds-per-acre
treatment with lead arsenate at temper-
atures of 60o, 600, and 700 F., and the
empirical threshold temperature of poi-
soning. (Somewhat diagrammatic.)







140


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500 40" 500 60" 70 80"
TEMPERATURE
@
Figure 4.- Relative velocity of poisoning of
third instars of the Japanese beetle with
the 1,000-pounds-per-acre treatment with lead
arsenate at temperatures of 50, 60, 70,
and 80 F., and the empirical threshold of
poisoning. (Somewhat diagrammatic.)






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80 *, .o- "

//
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60 500 POUNDS OF LEAD ARSENATE
60 /'/ /. AT CONSTANT TEMPERATURES -
0/ /0 OF 550 600 AND 70" -
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60 a 1,000cu POUNDS OF LEAD ARSENATE -l
///1 AT CONSTANT TEMPERATURE
S/I OF 50 60* AND 70'F. _
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40 .1II


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0 100 /00 600 400 500 600
DAY-DEGREE UNIT ABOVE 40"EF

Figure 5.-,.- Relation between the poisoning of the newly hatched
larvae of the Japanese beetle with the 500- and the l,O00-pound-
per-acre treatments with lead arsenate at constant temperatures
and accwltod thermal units above the empirical threshold.









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1000 1200 1400


ABOVE


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Figure 6.- Relation betweenn the poisoning of third instars of the
Japanese beetle with the lead arsenate treatment and accumulated
thermal units .ove the empirical threshold of 40 F. The blaok
dots are the ,'' a f-om constant-tempe:iture experiments carried
on at 50, 600, 700 and 800 F. in the laboratory, the solid line
is the curve 6cAermlned by the data, and the broken lines the
limits of expert .men:.al error. The open circles represent the
data obtained -om jummations of variable temperatures in the
field at Moorf. ,own, N.J. Two-third of these circles lie within
the limits of experimental error as determined for the constant-
temperature data. A, Data for the 500-pound-per-acre treatment;
B, for the l,pCO-poamd-per-acre treatment.


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Figure 7.-- Te Joint functional relation
between the percentage of the newly
hatched larvae of the Japanese beetle
poisoned, the quantity of lead arsenate
in the SQIl, and the accumulated thermal
units above the empirical threshold.
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Figure 7^ .- Te oit untina rlaio
betee the percentage^ ^r? oftePel
poisoned, the quatit of lead arsenate


inetheesinn the percenage of thernewly

units above the empirical threshold.
























































Figure 8.- The joint functional relation
between the percentage of third instars of
the Japanese beetle poisoned, the quantity
of lead arsenate in the soil, and the
accumulated thermal units above the empir-
ical threshold.








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.... sAV E k A 6 E.

6L, 4 4 ZONE IN JULY
,- |I BELOW 65F
Z, 65 -.1700F
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Figure 9.- Zones of equal temperaLures in
the eastern part of the United States
during the warm months of the year.















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ZONE


3
5
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AVERAGE
TEMPERATURE
IN JANUARY
BELOW 15F
15- ZOF
ZO'- Z"5T
25"--50F
30- 55"F
35"-4dF
406- 45"F
45"- 55"F
55"- 7dF


Figure 10.-Zones of equal temperatures in the
eastern pert of the United States during the
cold months of the year.


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UNIVERSITY OF FLORIDA
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