Variations in Sex Pheromone of the Australian Population of Fall Armyworm: Influence of Age and Mating Status

The rapid establishment of Fall Armyworm (FAW), Spodoptera frugiperda in Australia necessitates effective and sustainable management strategies. Pheromones offer a promising strategy for mitigating FAW damage through monitoring, mass trapping, and mating disruption. Understanding the pheromone composition of local FAW populations, as well as the variation in pheromone composition and production influenced by the mating status and age of FAW females, provides valuable insights into the factors contributing to pheromone production variability. This study investigated chemical composition of pheromone compounds of FAW population in Australia, temporal pattern of release, and the effect of mating status and age of FAW female on compounds release and production. Pheromone glands were collected by solvent extraction, whereas headspace volatiles were collected by solid phase microextraction (SPME) method. The sample contained four compounds (Z)-7-dodecenyl acetate (Z7C12Ac), (Z)-9-dodecenyl acetate (Z9C12Ac), (Z)-9-tetradecenyl acetate (Z9C14Ac) and (Z)-11-hexadecenyl acetate (Z11C16Ac), with Z9C14Ac present in a significantly higher amount. The maximum quantity of compounds from headspace volatiles was released between 4 to 6 h into the scotophase, while the compounds obtained from gland extraction varied across different phases of the scotophase. Younger FAW female released and produced higher amounts of compounds compared to the older individuals. Mated females have significantly higher compounds titre in their pheromone glands compared to the virgins, despite the latter releasing more volatile compounds. These findings highlight the impact of physiological factors on FAW pheromone compounds, offering valuable insights for developing sustainable strategies to manage FAW population in Australia.