Aggregation pheromone of the Qinghai spruce bark beetle, Ips nitidus eggers.
Volatiles from hindgut extracts of males of the Qinghai spruce bark beetle, Ips nitidus, from different attack phases (phase 1: unpaired males and phases 2-4: males joined with one to three females) and hindgut extracts of mated females were analyzed by gas chromatography-mass spectrometry (GC-MS)/flame ionization detection (FID) with both polar and enantioselective columns. The GC-MS/FID analyses demonstrated that unpaired males from attack phase 1 (nuptial chamber constructed) produced 2-methyl-3-buten-2-ol, approx. 74%-(-)-ipsdienol, and (-)-cis-verbenol as major hindgut components, and (-)-trans-verbenol, (-)-ipsenol, (-)-verbenone, myrtenol, and 2-phenylethanol as minor or trace components. The quantities of 2-methyl-3-buten-2-ol and especially ipsdienol decreased after mating during phases 2-4, whereas the quantities of (-)-cis- and (-)-trans-verbenol did not change. In contrast, the quantity of (-)-ipsenol seemed to increase as mating activity progressed. After mating with three females (harem size = 3; phase 4), only trace to small amounts of male-specific compounds were detected from I. nitidus male hindguts. Chemical analysis of the hindgut extracts of mated females showed only trace amounts of semiochemicals. A field-trapping bioassay in Qinghai, China showed that the four-component "full blend" containing the three major components, 2-methyl-3-buten-2-ol, (+/-)-ipsdienol, and (-)-cis-verbenol, plus a minor component, (-)-trans-verbenol, caught significantly more I. nitidus (male/female = 1:2.2) than did the unbaited control and two binary blends. The replacement of (+/-)-ipsdienol with nearly enantiomerically pure (-)-ipsdienol in the "full blend" significantly reduced trap catches, which suggests that both enantiomers are needed for attraction. On the other hand, removal of (-)-trans-verbenol from the active "full blend" had no significant effect on trap catches. Our results suggest that the three major components, 2-methyl-3-buten-2-ol, 74%-(-)-ipsdienol, and (-)-cis-verbenol (at 7:2:1), produced by unpaired fed males, are likely the aggregation pheromone components of I. nitidus, thus representing the first characterization of an aggregation pheromone system of a bark beetle native solely to China.
Zhang
Qing-He
QH
Sterling International, Inc., 3808 N. Sullivan Rd, Bldg 16p, Spokane, WA 99216-1630, USA. qing-he@rescue.com
Ma
Jian-Hai
JH
Zhao
Feng-Yu
FY
Song
Li-Wen
LW
Sun
Jiang-Hua
JH
D000080462:Acyclic Monoterpenes; D000818:Animals; D000081008:Bicyclic Monoterpenes; D005260:Female; D008297:Male; D039821:Monoterpenes / Q000032:analysis / Q000494:pharmacology; D000442:Octanols / Q000032:analysis / Q000494:pharmacology; D000439:Pentanols / Q000032:analysis / Q000494:pharmacology; D010675:Pheromones / Q000032:analysis* / Q000737:chemistry; D012726:Sexual Behavior, Animal; D014835:Volatilization; D048889:Weevils / Q000737:chemistry*
D000080462:Acyclic Monoterpenes; D000081008:Bicyclic Monoterpenes; D039821:Monoterpenes; D000442:Octanols; D000439:Pentanols; D010675:Pheromones; C009951:verbenol; C515391:ipsdienol; C027250:3-hydroxy-3-methylbutene