Sublethal effects of chlordimeform on chemical communication and other reproductive behaviors in the female cabbage looper moth (Lepidoptera: Noctuidae)

Insecticides can affect the complex coordination of activities associated with reproduction through their sublethal impact on the nervous system. Our objective was to document the effects of a sublethal dose (1% mortality) of chlordimeform on reproductive events in the female cabbage looper moth, Trichoplusia ni. A significantly higher percentage of females treated with chlordimeform initiated calling at some time during the scotophase. Chlordimeform stimulated pheromone emission early in the scotophase. However, late in the scotophase pheromone emission was significantly lower in chlordimeform‐treated females when compared with control females. Overall, a lower amount of pheromone was detected in glands of chlordimeform‐treated females. This effect was significant only during the second half of the scotophase. We suggest that chlordimeform stimulates pheromone transport to the gland surface and calling behavior resulting in depletion of pheromone reserves over the course of the scotophase. Chlordimeform also decreased the mating success of males. Oviposition and egg hatch were also affected by chlordimeform. Mated females treated with chlordimeform laid significantly fewer eggs than acetone‐treated females. In addition, hatchability of eggs laid by mated female T. ni treated with chlordimeform was significantly lower than for eggs laid by control females.