Effect of trap color, monochamol and α-pinene release rates, and α-pinene enantiomers on the capture of Monochamus alternatus Hope (Coleoptera: Cerambycidae)

Monochamus alternatus Hope (Coleoptera: Cerambycidae) is a known vector of the pine wood nematode (PWN), the causal agent of pine wilt disease. Effective control of this vector is essential to prevent the spread of PWN. Although pheromone traps have been employed to monitor the seasonal occurrence of M. alternatus, they have not yet been adopted as a practical method for field-level pest control. Therefore, to utilize pheromone traps for reducing vector populations, their trapping efficiency must be enhanced beyond the levels currently used for monitoring purposes. In this study, various pheromone trap conditions were evaluated through field trials to enhance the attraction of M. alternatus by modifying trap color, α-pinene enantiomers, and the release rates of pheromone and α-pinene. Among six tested colors, M. alternatus was most strongly attracted to black traps. In the enantiomer preference test for α-pinene, M. alternatus showed no significant difference in response among the different enantiomers. To assess the effects of pheromone and α-pinene release rates on M. alternatus capture, traps were baited with lures emitting varying release rates of monochamol (7–35 mg/day) and (−)-α-pinene (13–65 mg/day). Traps using the release rates of monochamol (35 mg/day) and (−)-α-pinene (52 mg/day) that resulted in the highest captures were 59.8 % more effective than those using the lowest release rates (monochamol: 7 mg/day; (−)-α-pinene: 13 mg/day). Notably, while there was no significant difference in male captures, traps with the optimal release rates captured 60.5 % more females. Although this study was conducted with limited replicates and relatively short trap spacing, the findings provide valuable insight into optimizing trap performance and lay the groundwork for developing more effective control strategies against M. alternatus.