Althoff Emily R, Aukema Brian H, Sullivan Brian T
Department of Entomology, University of Minnesota, St. Paul, MN, USA.
USDA Forest Service, Southern Research Station, 2500 Shreveport Hwy, Pineville, LA, USA.
J Chem Ecol. 2025 Feb 4;51(1):18. doi: 10.1007/s10886-025-01575-5.
The eastern larch beetle, Dendroctonus simplex LeConte, colonizes tamarack, Larix laricina (Du Roi) K. Koch, and has become a major tree killer in parts of its temperate North American range. To fill existing gaps in knowledge of this insect's pheromone system, we used gas chromatography-mass spectrometry to perform quantitative studies of pheromone production by unfed beetles of both sexes, founding females excised from newly established galleries in a tamarack log, and both sexes excised post-pairing. To identify olfactory stimulants and thereby possible, additional pheromone components, we performed gas chromatography-electroantennographic detection analyses with antennae of both sexes exposed to volatiles collections from the beetles. We also exposed unfed male and female beetles to juvenile hormone III (JH III) to identify pheromone components regulated through this mechanism. Both female and male beetles exhibited antennal responses to 1,5-dimethyl-6,8-dioxabicyclo[3.2.1]octane (frontalin), 3-methylcyclohex-2-en-1-ol (seudenol), and 3-methylcyclohex-2-en-1-one (MCH) in volatiles of solitary mining females. Within approximately 24 h of joining a male, female production of seudenol and MCH largely ceased while production of frontalin continued. Unfed females produced no more than minute amounts of pheromone, and application of JH III induced production of frontalin from some females but not seudenol or MCH. Unfed males and males exposed to JH III produced almost no volatiles, whereas paired males produced minute amounts of frontalin (possibly an artifact), no seudenol or MCH, and some oxygenated monoterpenes. We found that timing of production of certain pheromone components was inconsistent with their known activity.
东部落叶松小蠹（Dendroctonus simplex LeConte）以落叶松（Larix laricina (Du Roi) K. Koch）为侵害对象，在其北美温带分布区的部分地区已成为主要的树木杀手。为填补有关这种昆虫信息素系统现有知识的空白，我们使用气相色谱 - 质谱联用技术对未取食的雌雄成虫、从落叶松原木新形成的虫道中取出的初建雌虫以及配对后的雌雄成虫的信息素产生情况进行了定量研究。为识别嗅觉刺激物以及可能的其他信息素成分，我们进行了气相色谱 - 触角电位检测分析，将雌雄虫的触角暴露于来自这些甲虫的挥发物提取物中。我们还让未取食的雌雄甲虫接触保幼激素III（JH III），以识别受该机制调控的信息素成分。雌雄甲虫的触角对独居蛀干雌虫挥发物中的1,5 - 二甲基 - 6,8 - 二氧杂双环[3.2.1]辛烷（frontalin）、3 - 甲基环己 - 2 - 烯 - 1 - 醇（seudenol）和3 - 甲基环己 - 2 - 烯 - 1 - 酮（MCH）均有反应。在与雄虫交配后约24小时内，雌虫的seudenol和MCH分泌基本停止，而frontalin的分泌仍在继续。未取食的雌虫分泌的信息素量极少，施用JH III可诱导部分雌虫分泌frontalin，但不能诱导分泌seudenol或MCH。未取食的雄虫和接触JH III的雄虫几乎不产生挥发物，而配对后的雄虫产生微量的frontalin（可能是假象），不产生seudenol或MCH，以及一些氧化单萜。我们发现某些信息素成分的分泌时间与其已知活性不一致。
