Factors regulating exit of Bursaphelenchus xylophilus (Nematoda: Aphelenchoididae) fourth stage dispersal juveniles from their beetle vector Monochamus carolinensis (Coleoptera: Cerambycidae).

摘要

The pinewood nematode, Bursaphelenchus xylophilus (Steiner and Buhrer) Nickle, causes pine wilt. A specialized life stage, the {dollar}{bsol}rm J{bsol}sb{lcub}IV{rcub}{dollar} dispersal juvenile, is vectored by cerambycid beetles in the genus Monochamus. The mediation of J{dollar}{bsol}rm{bsol}sb{lcub}IV{rcub}{dollar} exit from beetle vectors is poorly understood. Attraction experiments suggest lipids attract reproductive nematodes, but J{dollar}{bsol}rm{bsol}sb{lcub}IV{rcub}{dollar} dispersal nematodes do not exhibit a preference for lipids, terpenoids or hydrocarbons. Nematode lipid content is implicated in J{dollar}{bsol}rm{bsol}sb{lcub}IV{rcub}{dollar} exit from its beetle vector. Significant differences in lipid content exist between J{dollar}{bsol}rm{bsol}sb{lcub}IV{rcub}{dollar}'s attracted to pine volatiles and fatty acids (termed low lipid nematodes) and J{dollar}{bsol}rm{bsol}sb{lcub}IV{rcub}{dollar}'s attracted to a beetle-associated hydrocarbon (termed high lipid nematodes). A hypothesis is proposed suggesting J{dollar}{bsol}rm{bsol}sb{lcub}IV{rcub}{dollar} response to exogenous chemical cues is mediated by endogenous lipid storage levels, and that this interaction properly times nematode entrance into and exit from its beetle vector.