Interaction of intrinsic and extrinsic chemical cues in the behaviour of Bursaphelenchus xylophilus (Aphelenchida: Aphelenchoididae) in relation to its beetle vectors

Abstract

AbstractBursaphelenchus xylophilus, its host trees and beetle vectors represent an unusual ecological system. The fourth stage, dispersal juvenile (JIV) of B. xylophilus is a specialised life stage that must alter its response to a variety of chemical cues over time to properly enter and exit its beetle vector. Neutral storage (NS) lipid content is proposed as a modifier of nematode response to beetleand tree-produced volatiles. The chemotactic response of JIV to a variety of chemicals was tested and the lipid contents of JIV attracted to particular chemicals were quantified. Nematodes with the lowest NS lipid content were attracted to β-myrcene, a pine volatile, while nematodes with the highest NS lipid content were attracted to toluene, a beetle cuticular hydrocarbon. A rolling fulcrum model of the integration of intrinsic (NS lipid) and extrinsic (volatiles) cues is proposed to explain the behavioural ontogeny of JIV in relation to the beetle vector.