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Monochamus alternatus is a very important vector of the pine wood nematode (Bursaphelenchus xylophilus) which is the causal agent of pine wilt disease. To reduce population density of M. alternatus, thiacloprid has been sprayed by aircrafts on pine forests. Thus, we examined the effect of aerial spraying as contact toxicity and thiacloprid residues of pine branches as ingestion toxicity on the mortality of M. alternatus in pine forests in Yangsan, Korea. In addition, the effect of aerial spraying on honey bees, Apis mellifera, was tested in the same locality. Thiacloprid was sprayed once a month from June to August in 2016. To test the effect of thiacloprid, eight M. alternatus and ten honey bees were put into each small mesh cage, which were hung on pine trees in each study plot. Thiacloprid appeared to be effective for reducing longevity of M. alternatus, while mortality and abnormal behaviors were not found for honey bees. In addition, longevity of M. alternatus beetles was declined by thiacloprid residues of pine branches compared to the control group. However, we found that dead pine trees infected by pine wood nematodes in the next year similarly occurred in our study area whether thiacloprid‐aerial spraying occurred or not. Consequently, thiacloprid sprayed by aircraft may be an effective control agent for Monochamus beetle adults without negative effect on honey bees, but aerial application to prevent expansion of pine wilt disease should be reassessed.

Oak tree death caused by symbiosis of an ambrosia beetle, Platypus koryoensis, and an ophiostomatoid filamentous fungus, Raffaelea quercus-mongolicae, has been a nationwide problem in Korea since 2004. In this study, we surveyed the yeast species associated with P. koryoensis to better understand the diversity of fungal associates of the beetle pest. In 2009, a total of 195 yeast isolates were sampled from larvae and adult beetles (female and male) of P. koryoensis in Cheonan, Goyang, and Paju; 8 species were identified by based on their morphological, biochemical and molecular analyses. Meyerozyma guilliermondii and Candida kashinagacola were found to be the two dominant species. Among the 8 species, Candida homilentoma was a newly recorded yeast species in Korea, and thus, its mycological characteristics were described. The P. koryoensis symbiont R. quercusmongolicae did not show extracelluar CM-cellulase, xylanase and avicelase activity that are responsible for degradation of wood structure; however, C. kashinagacola and M. guilliermondii did show the three extracellular enzymatic activities. Extracelluar CM-cellulase activity was also found in Ambrosiozyma sp., C. homilentoma, C. kashinagacola, and Candida sp. Extracelluar pectinase activity was detected in Ambrosiozyma sp., C. homilentoma, Candida sp., and M. guilliermondii. All the 8 yeast species displayed compatible relationships with R. quercus-mongolicae when they were co-cultivated on yeast extract-malt extract plates. Overall, our results demonstrated that P. koryoensis carries the yeast species as a symbiotic fungal associate. This is first report of yeast diversity associated with P. koryoensis.