CHEMOTACTIC RESPONSE OF PROPAGATIVE AND DISPERSAL FORMS OF THE PINEWOOD NEMATODE BURSAPHELENCHUS-XYLOPHILUS TO BEETLE AND PINE DERIVED COMPOUNDS

A specialized life stage of the nematode Bursaphelenchus xylophilus, t he JIV dispersal juvenile, is vectored by cerambycid beetles in the ge nus Monochamus. The propagative form of the nematode develops and repr oduces in susceptible pine trees. The chemotactic response of JIVs and the mediation of JIV exit from beetle vectors are poorly understood. Experiments were conducted examining chemical attraction by nematodes across representatives of fatty acid, monoterpene and hydrocarbon grou ps. Chemical attraction between propagative and dispersal forms of the nematode was compared. The influence of chemical attraction on JIV ex it from beetles was also examined. Propagative B. xylophilus were attr acted to the fatty acids, linoleic acid and 1-monoolein, while JIVs we re attracted to beta-myrcene and toluene. The presence of neither fatt y acids, monoterpenes nor hydrocarbons affected numbers of JIVs exitin g beetles. It is suggested that other factors, possibly endogenous in nature, are also involved in JIV exit behavior. (C) Orstom/Elsevier, P aris.