Periodical and Age-Related Variation in Sexual Communication of the Legume Pod Borer,Maruca vitrata(Lepidoptera: Crambidae)

Abstract

Periodical and age-related variation in female calling, sex pheromone titres, and male responsiveness were studied in the legume pod borer, Maruca vitrata. The results showed that females initiated calling on the first night after eclosion and called mainly on the third to fifth hour during scotophase. The percentage of calling increased from 1- to 3-day-old females and decreased from 3- to 5-day-old females. The quantification of the hexane extracts of pheromone glands by gas chromatography (GC) revealed that the titre of (E,E)-10,12-hexadecadienal (E10E12-16Ald), in pheromone glands was well synchronized with female calling at different ages. The titre of the primary sex pheromone component peaked at the fourth hour into the scotophase. The sensitivity of male antenna to primary sex pheromone E10E12-16Ald (10 ng/µl) varied considerably with age, but no time-dependent difference in electroantennographic responses was found. The temporal pattern of male M. vitrata responding to sex pheromone gland extracts in the wind tunnel demonstrated that males became sexually mature on the third night, which also paralleled the calling activity of females. This study indicated that there existed distinct periodical variations in female calling, titre of the primary sex pheromone component, and male responsiveness in Maruca vitrata during scotophase. These three parameters were well synchronous and age-dependent.