Fungal infection affects sexual signalling and mate choice in the sugarcane borer

Fungi associated with insects can influence host physiology and behaviour in ways that enhance their own persistence, survival and overall dispersal. Using a combination of behavioural, chemical and electrophysiological assays, we demonstrate that infection of the sugarcane borer ( Diatraea saccharalis ) by the plant‐pathogenic fungus Fusarium verticillioides affects insect sexual signalling and mating preferences. In wind tunnel assays, males were consistently oriented towards sex pheromone‐related odours emitted by infected calling female moths over those from non‐infected calling females. This behavioural change was not explained by differences in the rhythm of female calling behaviour, which remained consistent regardless of fungal infection. However, chemical analyses revealed that gland extract from infected females showed a small increase in the amount of Z 9‐16:Ald, a minor component of D. saccharalis sex pheromone. Also, infected females preferentially accepted infected males as mating partners, whereas non‐infected females showed no mating preference. Taken together, these results show that the infection by a plant‐pathogenic fungus alters sexual signalling and mating behaviour in the sugarcane borer, expanding our understanding of the ecological factors that influence insect sexual communication.