Aphid honeydew microbiota and impact on chemical ecology at multitrophic levels

Aphid honeydew, a sugar-rich secretion, hosts microbial communities that may influence natural aphid predators and parasitoids, contributing to pest control. These communities play a significant role in shaping multitrophic interactions; however, the bacterial diversity and succession patterns in honeydew across different aphid species and life stages remain understudied. This research investigates the bacterial composition using next-generation sequencing (NGS) and volatile organic compound (VOC) profiles through SPME-GC-MS analysis of honeydew from Aphis fabae and Acyrthosiphon pisum over four aging stages (fresh, 24-hour, 48-hour, and 72-hour). Behavioral assays in a wind tunnel with the hoverfly Episyrphus balteatus, a key aphid predator, revealed distinct preferences for honeydew type and age. Fresh A. fabae honeydew harbored a richer and more diverse microbial community than A. pisum honeydew, with notable shifts in VOC profiles as the honeydew aged. Behavioral assays also showed that 48-hour-aged A. pisum honeydew and fresh A. fabae honeydew elicited strong oviposition responses from E. balteatus. These findings highlight the ecological role of microbial succession in honeydew and reveal microbial targets that could modulate predator and parasitoid behavior. This work provides new insights into the chemical ecology of aphid-natural enemy interactions, offering potential pathways for innovative and sustainable pest management strategies.