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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. |