D(+)-Camphor as the key phytochemical cue is promising for the trap monitoring in a new monophagous camphor tree borer Pagiophloeus tsushimanus (Coleoptera: Curculionidae)

Abstract

The landscape plant, Cinnamomum camphora, is a broad-spectrum anti-insect tree species due to a diversity of terpenoids, such as D(+)-Camphor. However, C. camphora is selected as the unique host tree species by a monophagous weevil pest, Pagiophloeus tsushimanus. Deciphering the key olfactory signal components regulating its host preference could facilitate the monitoring and control strategies for this insect pest, but which is poorly understood. Herein, two host volatiles, D(+)-Camphor and Ocimene, can induce GC-EAD/EAG reactions in both male and female adults antennae. Correspondingly, Y-tube olfactometer assays showed that the two compounds were attractive to both male and female adults. In the field assays, self-made trap device baited with 5 mg dose D(+)-Camphor captured significantly more P. tsushimanus adults than isopropanol solvent control, but there was no sexual bias in adults captured. The trunk gluing trap device baited with bait can capture adults, but the number is significantly less than that of the self-made trap device and adults often fall after struggling. The cross baffle trap device never traps adults. Neither Ocimene nor isopropanol solvent control could capture adults. When used in combination, Ocimene cannot enhanced the attraction of D(+)-Camphor to both female and male adults. These results indicate that D(+)-camphor is a key active compound of P. tsushimanus adults for host location. Combination of the host-volatile lure based on D(+)-camphor and the self-made trapping device is promising to monitor and control this novel pest P. tsushimanus in C. camphora plantations.