Sublethal Doses of Insecticides Affect the Fecundity and Fertility of the iChrysodeixis includens/i?

摘要

The objective was to determine lethal concentrations and to evaluate the effects of sublethal doses of insecticides on Chrysodeixis includens under laboratory conditions. The standard population of C. includens was kept on artificial diet under controlled conditions (25°C ± 5°C, 60% ± 10 RU, 12:12 h). The active principles used were B. thuringiensis, Indoxacarb and Teflubenzuron. The CL25 and LC50 obtained from dose response curve (estimated from eight concentrations of each active principle) were diluted in water and applied to the back of third instar caterpillars and compared to the control (water). The insecticides used showed lethal and sublethal effects in C. includens. Bacillus thuringiensis was 6.21 and 2.79 times more toxic to soybean looper when compared to the products Indoxacarb and Teflubenzuron, respectively. Insecticides applied to the caterpillars reduced survival and affected the biomass gain with increased larvae and pupae longevity, with a significant reduction in fertility (40%) and fecundity (94.97%) in adults. In the present study it was observed that both survival and larval biomass gain have a direct effect on fecundity and fertility, respectively. Therefore the active ingredients Indoxacarb, Teflubenzuron and B. thuringiensis can be used in rotation as a tool in the C. includens.