Abstract:

Field experiments conducted in Aershan forest area, Inner Mongolia, showed that Ipslure 1 attracted much more the clerid predator Thanasimus substriatus (1 319 individuals) than Ips subelongatus (16 individuals). On the contrary, Ipslure 2 attracted much more I. subelongatus (24 104 individuals) than its predators (776 individuals). The biological activities of the two ipslures were further evaluated using electroantennogram (EAG) recording with antennae from I. subelongatus and T. substriatus. The EAG amplitude of I. subelongatus to Ipslure 2 (2.139 mV±0.678 mV females, 2.169 mV±0.473 mV males) was much stronger than to Ipslure 1 (0.440 mV±0.232 mV females, 0.297 mV±0.142 mV males). In contrast, the response of T. substriatus to Ipslure 1 (4.618 mV±1.106 mV females, 4.534 mV±1.087 mV males) was much stronger than to Ipslure 2 (2.209 mV±0.680 mV females,1.953 mV±0.601 mV males). The EAG results were in agreement with those obtained from field experiments. Gas Chromatography-Mass Spectrometry (GC-MS) analyses showed that Ipslure 1 mainly cis-geraniol (3.06%), Ipsenol (1.98%), (S)-cis-verbenol (80.36%), 1-verbenone (1.03%) and Ipslure 2 consisted of 2-methyl-3-buten-2-ol (4.78%), Ipsenol (63.71%), Cedrene (1.46%) and isocaryophillene (22.42%). The ipsenol-dominant blend attracted a high number of I. subelongatus while the (S)-cis-verbenol-dominant blend attracted a high number of T. substriatus. The knowledge can be applied for population monitoring and biological control of I. subelongatus.

Key words: Ips subelongatus, Thanasimus substriatus, Larix gmelinii, Ipslure, GC-MS, EAG, (S)-cis-verbenol, Ipsenol