Prolonged Exposure to Plant Volatiles Does Not Significantly Affect Pban Expression and Mating Behavior in Diamondback Moth [plutella Xylostella (Lepidoptera: Plutellidae)]

Abstract

Via plant volatiles, herbivorous insects locate hosts, find food, and release spawn for better survival and reproduction. Moreover, plant volatiles not only regulate the synthesis and release of sex pheromones in insects but also help them in the search and orientation of sources of sex pheromones. However, after prolonged exposure to plant volatiles, the changes mediating the mating behavior of diamondback moth (DBM) [Plutella xylostella (L.) (Lepidoptera: Plutellidae)] are unclear. DBMs were treated with allyl isothiocyanate, a volatile from cruciferous vegetables; however, it did not improve the mating rate and had a limited effect on mating rhythm. Moreover, the treatment inhibited mating behaviors in 3-day-old DBMs and decreased mating time in 5-day-old DBMs. After prolonged exposure to allyl isothiocyanate, the total mating time of DBM was not significantly different from that after prolonged exposure to n-hexane (control). However, the longest mating time after emergence in DBM after prolonged exposure to allyl isothiocyanate was delayed by 1 day compared with the exposure to n-hexane. Prolonged exposure to plant volatiles intensified the response behavior of DBM to sex pheromones; however, the content of Z11-16: Ald, a major component of sex pheromones, in female DBM gonads exhibited no change. Pheromone biosynthesis activating neuropeptide gene (PBAN) was downregulated in DBMs after prolonged exposure to plant volatiles. These findings suggested that prolonged exposure (6 h) to plant-derived volatiles has little effect on the mating behavior of DBM. The study provided practical guidance for applying phytochemicals in pest control by regulating insect behavior.