Abstract:

Effects of volatiles and their change of Larix gmeliniion the hostplant selection of a larch defoliator (Dendrolimus superans) were studied. The larch seedlings were treated by being cut, and the defoliator larva was feeding with 25% or 50% needles before bioassay experiments. The results showed that the mated female moths preferred to oviposite on healthy seedlings of Larix gmelinii, which accounted for 86.1%～89.5% of total eggs. Among different injuries, they preferred to oviposite on lightly injured plants, and the oviposition quantities were more on mechanically injured plants than on insect feeding plants. It was found that 92.4% eggs were laid on the ground and nets, and only 7.6% were deposited on plants after the female antennae were cut. The larvae tended to healthy plants rather than injured plants, which was consistent with the results of adult oviposition choice. β ocimene, myrcene and 3carene in the volatiles had repellent effects to femal adults, while camphene and phytol of 0.01, 0.1, 0.2, 0.5 μL·μL^－1 showed repellent effects to the males Besides, βpinene and S αpinene were attractive to both male and female adults in low concentrations, however showed repellent effect in high concentrations. Olfactory responses indicated that larvae were attracted by Rαpinene, phellandren, camphene and 3 carene, and repelled by myrcene.

Key words: Dendrolimus superans, plant volatiles, lure, repellent, hostplant selection, Larix gmelinii