Volatile profiles of three tree species in the northeastern China and associated effects on Sirex noctilio activity.
The wood-boring wasp, Sirex noctilio, is an invasive pest of numerous species of pine trees worldwide. The female S. noctilio wasps selectively lay eggs on different pine trees. The relationship between host volatile organic compounds and the wood wasps remains elusive. Here, the behaviors of the wood towards the host volatiles wasps were investigated. In Junde Forest Farm, three tree species, Pinus sylvestris var. mongolica, Larix gmelinii (Rupr.) Kuzen., and P. koraiensis Sieb. et Zucc., were girdled. Four treatments of trees, un-girdled, girdled, dying, and dead tree, were randomly selected as sample trees. Lindgren 12-funnel trap was placed on sample tree. The traps were checked once a week and the number of S. noctilio was recorded. The relationship between volatiles and S. noctilio attraction was analyzed by collecting volatiles from different tree species and treatments. trans-β-Ocimene, terpinolene, α-pinene oxide, and longifolene were present only in girdled P. sylvestris var. mongolica. Girdling the host tree can make released more volatiles, which was conducive to attracting S. noctilio. Effect of a single compound on S. noctilio is limited, but a mixture of multiple components formed a specific chemical signature to female S. noctilio. It could be useful in the monitoring and effective management of wood wasps.