Entrance and Distribution of the Pinewood Nematode Bursaphelenchus xylophilus on the Body of its Vector Monochamus galloprovincialis (Coleoptera: Cerambycidae)

Abstract

Aspects of the interaction between the pinewood nematode (PWN) Bursaphelenchus xylophilus (Steiner & Buhrer 1934) Nickle 1970 (Aphelenchida: Aphelenchidae) and its vector, the pine sawyer Monochamus galloprovincialis (Olivier 1795) were studied in Portugal, the only region where the two species coexist. It was found that, between January and July, third stage dispersal juveniles (J 3 ) were the most abundant B xylophilus life stages on pine wood in general and near insect larval galleries and pupal chambers with pupae. On the pupal chambers with callow adults, the dispersal J 4 larvae were the pre-dominant life stage. The analysis of M galloprovincialis' immature stages shows that 11 % of insect larvae (mean of 2 ± 0.7 nematodes per insect), 17% of pupae (4.4 ± 3.4) and 91% of callow adults (1089 ± 1219) (mean ± SD for all) had pinewood nematodes on them. Two and 30 days after emergence, 40 adult M galloprovincialis of both sexes were analysed for the distribution of the PWN on their bodies, with the vast majority of nematodes detected on the thoracic region, most abundantly on the meta-thorax. The body segments containing less nematodes were the antennas, legs, wings and elytra. The results are compared with other well-studied B xylophilus-Monochamus associations from North America and East Asia, and the possibility of surging new functional interactions between the PWN and the European Monochamus spp is briefly discussed.