Functional roles of aphid-associated microbes in multitrophic interactions

Aphids (Hemiptera: Aphididae) are economically important pests of crops worldwide. Although increasing
evidence suggests that aphid-associated microorganisms have potential applications in integrated pest
management (IPM), our understanding of their roles in multitrophic interactions remains limited. This
review synthesizes current knowledge on aphid-associated endosymbionts and secretion-associated
microbes, focusing on their influence on aphid physiology, behavior but also on interactions with host
plants and natural enemies. Firstly, the functional diversity of endosymbionts, which contribute to
improved nutrition, heat tolerance and resistance to pathogens, parasitoids and pesticides was highlighted.
Secondly, we examined how microbes from aphid saliva and honeydew can act as molecular cues to induce
plant defenses and modify the behaviour of aphidophagous beneficials. Special attention was given to
honeydew-associated microbial volatiles (mVOCs), which can modulate the behavior of predators and
parasitoids. Finally, emerging biocontrol strategies that leverage symbionts and mVOCs were discussed to
propose future directions for integrating microbial ecology into sustainable aphid management.