The pinewood nematode, the causal agent of pine wilt disease, is vectored from wilt-killed to healthy pine trees by Monochamus beetles, though numerous beetles of various genera in the families Cerambycidae, Curculionidae and Scolytidae also colonize wilt-weakened and killed pines. We examined several factors affecting the number of nematodes carried by Monochamus alternatus and Acanthocinus griseus which emerged from pine wilt-killed trees. M.alternatus carried many nematodes, however, A.griseus carried few or no nematodes. The higher intensity of blue-stain of M.alternatus pupal chamber walls compared with A.griseus ones could be responsible for the great number of nematodes carried by M.alternatus. All chambers of M.alternatus were constructed in the sapwood, while most A.griseus chambers were built just beneath the bark. Therefore, this might make a difference in the number of nematodes carried by the two beetle species.The number of nematodes carried by M.alternatus ranged from 2 to 27,200. Very intense blue-stain on the pupal chamber walls of the beetle increased the numbers of nematodes carried by the beetle which emerged from the chambers. There were differences in the numbers of nematodes carried by a beetle among individuals of the trees from which the beetle emerged.
Miyazaki et al.(1977) reported that unsaturated fatty acids, i.e.linoleic, palmitoleic and oleic acids, were effective in aggregation of the nematodes. To examine the effects of saturated and unsaturated fatty acids on the number of nematodes carried by both the beetle species, we also analyzed these fatty acids around the chambers of these beetles by GC-MS.
Species 1: Coleoptera Cerambycidae Monochamus alternatus (Japanese pine sawyer)
Species 2: Coleoptera Cerambycidae Acanthocinus griseus (marmorate thick-legged longicorn beetle)
Keywords: Pine wood nematode, fatty acid
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