A female aphrodisiac and male mating inhibitor: dual functions of the male-specific sex pheromone in the beet webworm, Loxostege sticticalis L.

Abstract

BACKGROUND Male insect sex pheromones play a critical role in reproductive behavior by synchronizing female receptivity and deterring rivals, thereby increasing reproductive success. As a major worldwide migratory pest, the beet webworm, Loxostege sticticalis L., has been the subject of sex pheromone research - though previous efforts have focused exclusively on female-produced signals. The male-specific sex pheromone and its functions remain largely uncharacterized. This study therefore aimed to identify the male-specific pheromones in this species and elucidate their behavioral effects on conspecifics. RESULTS Gas chromatography-mass spectrometry (GC-MS) analysis of crude extracts from abdominal tips of female and male moths identified a total of 15 compounds. Thirteen compounds were detected in both sexes, whereas (E)-ocimene and (Z)-11-hexadecen-1-yl acetate (Z11-16:Ac) were male-specific, with (E)-ocimene produced at an eight-fold higher level than Z11-16:Ac. Both compounds elicited significant electrophysiological responses in antennae of both sexes. In behavioral assays, the two components used separately or as a binary blend increased calling behavior in 3- and 4-day-old females, but not in older females. In males, the binary mixture reduced courtship persistence and mating success in younger males (3-5 days old); this effect diminished in 6-day-old males. CONCLUSION The dual function of these male pheromones - enhancing female receptivity while suppressing conspecific male competition - represents an adaptive strategy that facilitates rapid population establishment after migration. These findings provide critical insights into chemical communication in the beet webworm and establish a mechanistic foundation for developing novel pest management strategies targeting reproductive behavior. © 2025 Society of Chemical Industry.