Behavioural responses of peach potato aphid, M yzus persicae S ulzer (

Entomopathogenic fungi (EPF) can suppress aphid populations through biological control, but whether EPF‐associated volatile cues influence aphid behaviour remains poorly understood. We investigated the olfactory response of apterous  Myzus persicae  to  Beauveria bassiana  and to conspecifics infected with  B. bassiana .

Aphid responses were assessed using four‐arm olfactometer assays. In the first assay, aphids were exposed to  B. bassiana ‐colonised agar, sterile agar and two blank‐air controls. In the second, aphids were exposed to odours from EPF‐infected conspecifics, healthy conspecifics, an agar control and a blank‐air control. Time spent within each odour field was converted to compositional proportions and analysed following centred log‐ratio transformation.

Aphids showed no detectable olfactory response to  B. bassiana ‐colonised agar alone. In contrast, aphids responded positively to odours associated with infected conspecifics, spending significantly more time in this odour field than in those containing healthy aphids, agar or blank air.

These findings demonstrate that the behavioural response of  M. persicae  to EPF‐associated cues is context dependent, with cues generated during host infection appearing more salient than fungal odours presented in isolation.

The results extend our understanding of pathogen‐mediated chemical communication in aphids and suggest that EPF infection may influence host–pathogen interactions and potentially pathogen transmission in ways that are not predicted by repellency‐based models alone.