Objective To investigate and study the species of long-horned beetles carrying Bursaphelenchus xylophilus in the occurrence area of B. xylophilus in Liaoning, China, and to further clarify the species of vector insects of B. xylophilus and the carrying amount of B. xylophilus of the main vector insects in the occurrence area, in order to provide reference for the research of prevention and control technology of B. xylophilus in Liaoning epidemic area.

Method From the first ten days of May to the late September in 2018 and 2019, the species of long-horned beetles were investigated at the epidemic areas of B. xylophilus in Fushun, Dalian, Dandong and Benxi of Liaoning Province. The adults were collected by traps and their morphological characters were identified and the amount was counted in laboratory. In April, 2020, the amount of Monochamus saltuarius carrying B. xylophilus were investigated in the Dahuofang Forest Farm of Fushun. The M. saltuarius emerging from the infected wood wrapped by iron net were cutting into pieces and soaked into Beman funnel. Then the nematodes were isolated and be identified through both morphological and genetic characters.

Result 9 species of long-horned beetles infesting pine trees were trapped in the pine wilt epidemic area in Liaoning Province, namely: M. saltuarius, M. alternatus, Arhopalus rusticus, Asemum striatum, Rhagium inquisitor, Acanthocinus griseus, Moechotypa diphysis, Acanthocinus aedilis, and Dorysthenes sternalis. Among them, there were 4 species of long-horned beetles, such as Monochamus saltuarius, Monochamus alternatus, Arhopalus rusticus, and Asemum striatum carrying B. xylophilus. A total of 160 Monochamus alternatus adults emerged from infested wood were tested. The average number of B. xylophilus tested was 513.69 per beetle, and the maximum of B. xylophilus isolated from one beetle was10060.

Conclusion According to the amount of long-horned beetles trapped in the forest and the amount of B. xylophilus isolated from the beetles, it is concluded that Monochamus saltuarius is the main long-horned beetle species in Liaoning epidemic area of pine wilt disease, and Monochamus saltuarius is probably the main insect vectored B. xylophilus. However, the population of Arhopalus rusticus is larger than the other long-horned beetles in Dalian epidemic area, but whether it is a kind of vector of B. xylophilus has yet to be determined. At present, the main vector of B. xylophilus in Dalian is Monochamus alternatus.