Field trap test for bioassay of synthetic (1S,4R)-4-isopropyl-1-methyl-2-cyclohexen-1-ol as an aggregation pheromone of Platypus quercivorus (Coleoptera: Platipodidae)

Abstract

An ambrosia beetle, Platypus quercivorus, is a vector of Japanese oak wilt, which causes massive mortality of oak trees in Japan. Previous studies have identified (1S,4R)-4-isopropyl-1-methyl-2-cyclohexen-1-ol ((−)-IMCH) as the major component of the aggregation pheromone of P. quercivorus. We tested the ability of synthetic (−)-IMCH to attract P. quercivorus adults. The synthetic compound attracted 14.4 times as many P. quercivorus, of both sexes, as control traps. Control and (−)-IMCH-baited traps both captured 3.32 times as many males as females, probably because of the nature of Lindgren funnel traps and of male-biased emergence sex ratio early in the season of adult flights. (−)-IMCH was proved to be a major component of the aggregation pheromone of P. quercivorus.

Keywords:

• Ambrosia beetle
• Field bioassay
• Japanese oak wilt
• Quercivorol
• Sex ratio

Acknowledgments

This study was supported by a Grant-in-aid from the Ministry of Education, Culture, Sports, Science, and Technology (MEXT) (17405028) to NK, and by a grant from the twenty-first century COE Program by MEXT (1440101) to Kazuichi Hayakawa. We are deeply grateful to the staff of the Ishikawa Forestry Research Station for assisting in the field tests. We also thank Susumu Goto and Hayato Iijima for their helpful suggestions on statistical analysis.