The First Record of Monochamus saltuarius (Coleoptera; Cerambycidae) as Vector of Bursaphelenchus xylophilus and Its New Potential Hosts in China

SIMPLE SUMMARY: During a survey of pine wilt disease in 2017, thousands of dead pitch pines (Pinus koraiensis) were discovered in Fengcheng, Liaoning Province, China. Samples were taken from several regions of the bole, and Bursaphelenchus xylophilus was collected from the dead pitch pine samples. Monochamus saltuarius is an indigenous insect in this area, but there is no experimental evidence that M. saltuarius can transport B. xylophilus in China. The experimental results showed that M. saltuarius was the new vector of pine wilt disease in China. In laboratory experiments, M. saltuarius fed and transmitted B. xylophilus not only on pines but also on other conifers. Taxus, Juniperus, Sabina and Podocarpus are new tree species upon which B. xylophilus can be fed and transmitted by M. saltuarius. Picea pungens, Picea asperata, Abies fabri, A. holophylla, Larix principis-rupprechtii, L. olgensis, Juniperus formosana, Sabina chinensis and Podocarpus macrophyllus are new species of coniferous trees known to be able to be infected by B. xylophilus in a laboratory setting. This study raises awareness to prevent the disease from expanding and provides a reference for the control of pine wilt disease. ABSTRACT: Pine wilt disease was first discovered in Dongtang town, Liaoning Province, China, in 2017. However, no record of Monochamus alteratus existed in Fengcheng, where M. saltuarius is an indigenous insect, and no experimental evidence has thus far indicated that M. saltuarius can transport the Bursaphelenchus xylophilus in China. In this study, we investigated whether M. saltuarius is a vector of B. xylophilus in China. On the sixth day after eclosion, beetles began to transmit nematodes into the twigs. The transmission period of nematodes is known to be able to last for 48 days after beetle emergence. In laboratory experiments, M. saltuarius fed and transmitted B. xylophilus not only on pines but also on other non-Pinus conifers. The non-Pinus conifers preferred by M. saltuarius for feeding are Picea pungens, Picea asperata, and Abies fabri. The experimental results show that M. saltuarius functions as a vector of B. xylophilus in northeast China.