اثرات کشنده و زیرکشنده حشره‌کش‌های تیودیکارب، پیریدالیل و کرومافنوزاید روی فراسنجه های زیستی کرم میوه‌خوار گوجه‌فرنگی helicoverpa armigera (lepidoptera: noctuidae)

در این پژوهش، اثرات کشنده و زیرکشنده حشره‌کش‌های تیودیکارب، پیریدالیل و کرومافنوزاید روی کرم میوه‌خوار گوجه-فرنگی helicoverpa armigera (hübner) با روش غذای مصنوعی آمیخته با محلول سمی و در شرایط آزمایشگاهی بررسی شد. بنابر نتایج زیست‌سنجی روی لاروهای سن دوم کرم میوه گوجه‌فرنگی، مقادیر lc50 برآورد شده برای حشره‌کش‌های مذکور، به ترتیب 209.6، 48.09، 2.74 میلی‌گرم ماده موثر بر لیتر بود. نتایج اثرات زیرکشنده نشان داد که غلظت‌های lc30 حشره‌کش‌ها، فراسنجه‌های زیستی و جدول زندگی کرم میوه‌خوار گوجه‌فرنگی را تحت تاثیر قرار دادند. بیشترین مدت زمان نشوونما مراحل مختلف نارس در تیمارهای پیریدالیل (35.85 روز)و کرومافنوزاید (36.39 روز) مشاهده شد. در تیمارهای پیریدالیل و کرومافنوزاید کمترین طول عمر حشرات ماده (10.77 و10.33 روز) و کمترین باروری کل ( 294.9 و 236.08 تخم بر ماده) مشاهده شد. همچنین کمترین نرخ‌های ذاتی (r) و متناهی (λ) افزایش جمعیت در تیمارهای پیریدالیل (0.102 و 1.107 بر روز) و کرومافنوزاید (0.09 و 1.09 بر روز) و بیشترین آنها در شاهد (0.183 و 1.201 بر روز) مشاهده شد. نتایج نشان داد که حشره‌کش‌های پیریدالیل و کرومافنوزاید اثر کشندگی و زیرکشندگی قابل توجهی برای کرم میوه‌خوار گوجه‌فرنگی دارند و می‌توانند در مدیریت تلفیقی کرم میوه خوار در مزرعه گوجه‌فرنگی استفاده شوند.

lethal and sublethal effects of thiodicarb, pyridalyl and chromafenozide on the life table parameters of the tomato fruitworm, helicoverpa armigera (lepidoptera: noctuidae)

background and objectivesthe tomato fruitworm helicoverpa armigera (hubner) is a highly versatile pest found worldwide. due to its high mobility, short growth period, and high reproduction rate, it has become a highly damaging agricultural pest in various regions. one effective and long-lasting strategy for managing pests, like the tomato fruitworm, is to utilize a combination of chemical insecticides and other control methods in an integrated pest management program. insecticides have direct effects on mortality rates and indirect effects by altering the physiological or behavioral characteristics of the target pest. in a sustainable agriculture strategy, it is crucial to assess the direct and indirect effects of insecticides on the biological parameters of the target pest. this study aimed to investigate the lethal and sublethal concentrations of thiodicarb, pyridalyl, and chromafenozide on the life table parameters of the tomato fruitworm.materials and methodsthe bioassay of insecticides on the second instar larvae of the tomato fruitworm was conducted by adding the insecticides to the artificial diet. in control, distilled water was used instead. to study the sublethal effects of thiodicarb, pyridalyl, and chromafenozide insecticides, 200 tomato fruitworm larvae of second-instar were selected from the laboratory population from a growth chamber and then transferred to containers. after three days, 70 alive larvae were randomly selected and transferred to individual rearing containers containing an insecticide-free diet in each treatment. all demographic parameters were measured individually in each treatment. the data related to the mortality of the tomato fruitworm larvae was analyzed by the probit method in a bioassay. for each insecticide, the dose response line and the lc50 slope were estimated at a 95% confidence level. one-way analysis of variance was used to evaluate the sublethal effects of the tested insecticides on the duration of immature stages and the developmental rate. a comparison of means was done with tukey’s test at a 5% probability level. the sublethal effects of the insecticides on the demographic parameters of pests were analyzed using the age-stage-specific bisexual life table theory. resultsaccording to the bioassay tests on the tomato fruitworm larvae, the estimated lc50 values for thiodicarb, pyridalyl, and chromafenozide, were 209.62, 48.09, and 2.74 mg a. i. /l, respectively. the results of the sublethal effects showed that lc30 values of insecticides could alter the pest’s biological and life table parameters. the lowest length of embryonic, larval, pre-pupal, pupal, immature, pre-, and post-oviposition periods was recorded in the control treatment. on the other hand, the longest time of these parameters was observed in the chromafenozide and pyridalyl treatments. the highest lifespan of males and females and the maximum fertility of pests were observed in control. however, the lowest of these parameters were observed in the chromafenozide and pyridalyl treatments. none of the insecticides had a significant effect on the sex ratio of the tomato fruitworm (1:1). the highest value of net fecundity rate (r0), intrinsic rate of increase (r), finite rate of increase (λ) were observed in the control treatment and the lowest values of these parameters were observed in the chromafenozide and pyridalyl treatments. the lowest average value of total generation period (t) and doubling time (dt) was observed in the control treatment, and the highest value of these parameters was observed in the chromafenozide and pyridalyl treatments.discussionafter conducting tests to evaluate the lethal and sublethal effects of insecticides on the biological parameters of tomato fruitworms, it was found that pyridalyl and chromafenozide had shown more effects than that of thiodicarb. it can be concluded that pyridalyl and chromafenozide insecticides are more effective on the tomato fruitworms than thiodicarb. therefore, it is recommended to use pyridalyl or chromafenozide insecticides along with the other control methods in an integrated pest management (ipm) approach for the tomato fruitworms.