Comparison of transmission of Bursaphelenchus mucronatus via two different pathways from Monochamus saltuarius to host trees

What is it about?

A tiny nematode, Bursaphelenchus mucronatus, lives on fungi in dead conifers and is transmitted by longhorn beetles of Monochamus species. Feeding and oviposition wounds made by beetles are primary transmission pathways to healthy and recently dead trees, respectively. Monochamus saltuarius female adults carrying the nematode were reared singly, allowing to mate with nematode-free males. The survival time, lifetime fecundity and other reproductive traits decreased with increasing number of nematodes carried by a newly-emerged adult (initial nematode load). The number of nematodes transmitted via oviposition wounds increased with the initial nematode load and the number of oviposition wounds. The number of nematodes transmitted via feeding wounds decreased with increasing number of oviposition wounds. Most temporal patterns of nematode departure and transmission via oviposition or feeding wounds from individual beetles had a peak in the medium and heavy initial nematode loads. The nematode departure curve was significantly similar in shape to each of nematode transmission curves via oviposition and feeding wounds for individual beetles. The proportion of nematodes transmitted via oviposition wounds was significantly greater than that via feeding wounds, which helps the nematode persist in forests because of its extinction in healthy trees.

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