الفهرس 
Material and methodsOnly 14 pages are availabe for public view
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Abstract
The pink bollworm, Pectinophora 80BByplella (Saunders)
are subtropical insect species, which feed on annual plants.
Those species are multi-voltine with diapause likely to
occur at any season of the year apparently independently
on the weather.. Modern methods of insect control require
a detailed knowledge of insects seasonality since accurate
forecast of season activity are necessary tor population
managemen t.
The aim ot the present work is to study the effect
of some tactors on the initiation and termination of
dispause stage of the pink bollwora larvae.
Samples of larvae were collected at weekly intervals
throughout the cotton season from flowers, green and dry
bolls from Kalyobia Governorate. Samples from each stage
of plant growth were reared in the laborato~ at a conso
tent temperature of 27 c. 4!a lnstar larvae were sexed
and the sex ratio was estimated. Normal and undersized
pale coloured larvae, referred to as abnormal larvae
were collected and sexed.
I.a. Sex ratio during the season of 1985 :
Results showed that at the beginning of the season
in June the sexual ratio was in favour of males () f!: 1 .)
in samples collected from infested flowers.
The reverSe was true in August where the ratio was
(1 rI’: 1.8 f). In Nov”’ber IllldDecember the ratio became
again in ravour or malee (1.6 0’: 1 f) and (2.5 ~: 1 ’)
respectively.
r ,b. Normal. and abnormal larvae :
Abnormal larvae appeared throughout the August-November
period, and it Was prOPortionally higher among malee. Thoe
larvae invariably railed to enter into diapause stage, e
accordingly they were completely abSent in December where
all the larvae collected were in dlapause.
II. Inrluence or temperature on diapause in the 41a instar larvae :
The erfect oro three conetant temperatures were etudied,
i.e. 15, 20 end 27 C on larval weights, time end percentage
of PUpation, malformation inpupaa end adulta, percentaga
of diapauee were estimated after 30 days end si% months.
There Wae a general loss of lsrval weight at all temperaturee
inveatigated snd in both ee%ee, males were more
afrected thllllr”’alee end the 1IIegn1 tUde or loee wae
inversoely proportional to temperature being negligible at 27 C.
proportional to temperature end at 27oC tha larval
The duration of the larval period waa inveraely
duration period did not reach the threshold of dispause, o
while the degreeS of 15 and 20 C were conducive to
diapause.
Pupation incressed with the rise of temperature to
o
resch a maximum of 100 ~ at 27 c. At lower temperature
more females pupated than males. o
Malformations in pupae occurred at 15 snd 20 C but
not at 27oc. The percentage of malformation was inversely
proportional to temperature and males were more affected
than females.
Low temperatures extended the duration of ths pupal
period and weight wes reduced by low temperatures the
effect was more noticeable with males.
The percentege of eclusion of adults was low at the
o temperatures of 15 and 20 C, never reaching 50 %. this
proportion was always lower among males compared with
femaleS. This percentage was 100 ~ in both sexes at
o
27 c.
Diapausing larvae : By lowering the temperature more
diap8U
se
occurred with a larger proportion among males.
statistically the effect of temperature and the inter~
action of s8% and temperature were significant.
o
At the temperatures of 15 and 20 C. 50 ~ of larvae
went into extended diap8Use for six months with higher
percentage of males than females. Temperature, sex and
their interaction were found to be statistically signio
ficant. At 27 C, no extended diapause occurred.
At the end of six months the effect ot the three
constant temperatures on total mortalities throughout
the experiment was calculated. Percentages at mortalities
rose at low temperatures with higher percentage
o mortalities in males. At 27 0, no mortalities occurred.
The effects of temperature and sex on mortalities were
found to be statistically significant.
III. Effect of sublethal doses of insecticides on diapause :
The above experiment was repeated using 4th instar
larvae dosed with ca. 10 % dosages of one of three
insecticides; fenvalerate, cypermethrln and chlorpyritos.
Log-dose mortality line indicated that the descending
order of toxicity of the three insecticides was
fenvalerate, cypermethrin and ehlorpyrifos. Statistical
analysis showed the differences between the susceptibilities
at males and temales to be not significant.
~ substantial loss at weight occurred one week after
treatment among treated larvae at the three constant
temperatures investigated. the loss was higher among
females than males. Treatment with insecticides did
not prevent diapause at low temperatures, but there was
a reduction of dispausing larvae, the reduction was more
noticeable among males and the most effective insectieides
was :t’envalerate.
The lowest percentage of pupation at the two dispause
inducing temperature occurred in male and female larvae
exposed to cypermethrin, while fenvalerate and chlorpyrifos
were comparable in males, in females pupal formation
figures were slightly higher in chlorpyrifos.
An increase in the percentage of malformations in
pupae Occurred in survivals ot insecticides treatments,
the phenomenon was discussed alongsIde reports in the
lIterature on morphogenetic effects of pesticides.
Insecticidal treatment prolonged pupal duration at
the three constant temperatures used with a more pronounced
effect on males, and as would be expected pupal
weights were adversely affected by insecticidal treatment,
the least reduction in weight was brought about by
chlorpyrifos.
An additional reduction in adult ecluatOD was brought
about by insecticides, the reductions were larger in
females than in males. Malformations of ada!ts were
increased among survivals ot insecticidal treatments.
Treatment with insecticides reduced the percentage
of diapausing larYae, the reduction varied with aeX end
insecticide. Analysis of varience of this par~eter
showed that the effect of temperature end insecticides
were significant but the effect of seX waS not.
EXpOsure to insectiCides reduced the percentages of
larYae entering extended diepeuse (6 monthS) at the temperatures
of 15 end 20oc. The reduction was more pronounced
in male then in female larvae. Ststistical enalysiS supported
these observations.
Total mortalities after 6 months were computed, it
was evident that insecticidal treatment increased this
percentsge significantly at the three constent temperaturea
used end with the three insecticides investigated.
IV. Influence of some allelochemicS on the biology of the
newly hatching larYae of Eo. gossYl!1ella (Saund.) I
The newly hatching larvae were reared on diets cont- o
sining gossypol and coumarin at 21 C suffered mortalities
throughout the larval stage. Ilortalities were concentrationa
dependent, probit analysiS showed that coumarin was
about 4.56 time more toxic than gossypol at LC50 level.
The two compo~ds cansed a slowing down of the rate of
development of larvae the figpreS were statistica
l1
1
significant.
Weight of larvae and pupae were reduced, the reductions
were proportional to concentration, in coumarin,
male larvae were affected more than temales, those
deductions were verified statistically. There was a
reduction in the percentage pupation in the two compounds
and the reduction was proportional to concentration.
There were substantial increases in malformed pupae,
the etfect was more pronounced with coumarin.
The two compounds caused elongation ot the pupal
duration, coumarin caused more elongation than gossypol
for this period.
There were appreciable percentages ot failure to
produce adults from pupae in the two compounds, percentages
were higher in coumarin. Among tormed adults there
were persistant, dose dependent percentages of malformed
adults, gossypol was more effective.
The two compounds slow down the rate of development,
but the figures obtained did not prove the compounds to
be dlapause induces.
Adults from larvae reared on the two compounds laid
significantly less numbers of eggs. The frequency of
mating was adversely affected by the two compounds and
hatchability among the eggs laid was reduced, there wss
a slight decrease in the proportion of mated females in
Seventeen amino acids were identified and quantified
in the body hydrolysates of larvae in the above conditions.
There was 3-4 folds increase in glutamic acid in diapausing,
abnormal and coumarin treated larvae in comparison
with aetive larvae.
Similar patterns were found for valine, isoleucine
and leueine, the three being reported 8S essential amino
acids to insects and similar in structure, routes or
synthesis and catabolism.
There was some defieiency of tyrosine in abnormal
and coumarin treated larvae. An increase in ammonia was
noticed in active males.
The overall picture suggested that a lesst part ot
the increase in weight of diapeusing larvae may be due
to an increased protein content.