Effects of volatiles of non-host plants and other chemicals on oviposition of Monochamus alternatus (Coleoptera: Cerambycidae)

The response of adult females of Monochamus alternatus to volatiles of non-host plants was evaluated using a Y-tube olfactometer. Eight non-host plant species were tested, namely Broussonetia papyrifera, Cedrus deodara, Firmiana simplex, Metasequoia glyptostroboides, Platycladus orientalis, Populus xiaohei, Salix babylonica and Sophora japonica. The volatiles of all test species, except those of C. deodara, repelled the females in the olfactometer bioassays. Oviposition by adult females on the host plant, Pinus massoniana, was deterred by the volatiles of non-host plants and by some other chemicals. Volatiles of P. orientalis had the strongest oviposition-deterring activity and those of S. japonica the least. Volatiles of C. deodara had no influence on oviposition of the females. Selected chemicals, namely benzaldehyde, citronellal, essential oil of Mentha spicata, eucalyptol, nerolidol, nicotine and salicylaldehyde, strongly deterred the females from oviposition, and nicotine caused maximum decrease in egg-laying and scar-excavation.