Effects of insecticides on sex pheromone communication and mating behavior in Trichogramma chilonis

Trichogramma chilonis Ishii is an important natural enemy of several lepidopterous pests on crops. The effects of two common insecticides on sex pheromone communication and mating behavior in T. chilonis were evaluated in the laboratory. When only males were exposed to insecticide, beta-cypermethrin LC20 exposure induced significant decrease in sex pheromone perception by males and significant increase in males' courtship and copulation frequency; beta-cypermethrin LC1 exposure caused significant decrease in males' courtship and copulation frequency. Males exposed to spinosad LC20 exhibited significantly slower initiated courtship and significantly shorter total copulation duration, and the males exposed to spinosad LC1 exhibited significantly increased sex pheromone perception, compared with control. When both males and females were exposed to insecticide, significantly more courtship and copulation were conducted by treated pairs that survived insecticide (beta-cypermethrin or spinosad) LC20 than control pairs. Our study suggests that even the LC1 and LC20 of tested insecticides could affect the sex pheromone communication and mating behavior in T. chilonis.