Olfactory responses of Argentine stem weevil to herbivory and endophyte-colonisation in perennial ryegrass

Abstract Argentine stem weevil adults (ASW, Listronotus bonariensis ) feed on the leaves of agricultural grasses and their larvae mine pseudostem, causing extensive damage that can result in plant death. Plants emit volatiles serve as signals to host-searching insects these odours be altered by both herbivory fungal endophyte-infection. This study investigated whether ASW utilise olfaction identify host plants, perennial ryegrass ( Lolium perenne ), if conspecific or presence Epichloë festucae var. lolii endophytes (strain wild-type AR1) influenced such responses. Results from olfactometer bioassays established were able olfactory response orient towards released further, weevils displayed a preference for plants previously damaged weevils. However, there was no evidence had ability distinguish between endophyte-infected endophyte-free using alone. Using push–pull extraction technique, thirteen volatile compounds identified blend ryegrass. Endophyte found alter quantities emitted this forage grass. suggests despite observing differences blend, do not perceive endophyte (wild-type alone must rely other cues, e.g. contact chemoreception post-ingestional malaise, detect bioactive an otherwise acceptable plant.