The effect of mating on the sex pheromone system of the yellow mealworm beetle, <em>Tenebrio molitor</em> L. (Coleoptera: Tenebrionidae)

The mating behavior of the yellow mealworm beetle (Tenebrio molitor L.) is mediated by several pheromones, including a female-produced male attractant, (R)-(+)-4-methylnonanol (4-MNol); a male-produced female attractant, (Z)-3-dodecenyl acetate; a male-produced anti-aphrodisiac; and at least one copulation pheromone. The objective of this study was to investigate the effect of mating on this complicated pheromone system. Glass rod bioassays were conducted to determine the response of virgin adult male beetles to the surface extracts of adult female beetles, prepared from virgin females, females allowed to mate once (extracted 0, 0.5, 1 or 2 h after mating), and females allowed to mate over an extended period of time (0, 1, or 21 h). Mating caused an immediate but temporary inhibition of the ability of the female extracts (FEs) to attract the males. This wore off relatively quickly, since FEs prepared 0.5–1 h after mating were as attractive as the virgin FE. Two hours after mating a second inhibition of attraction was observed, which was likely due to a drop in the titer of 4-MNol. Gas chromatographic analyses confirmed that the level of 4-MNol dropped after mating, from ∼40 ng per virgin female to below our levels of detection in mated females. A single mating event, or the 1 h extended mating, did not significantly affect the ability of the FEs to elicit copulation behavior (CB) from the males. However, FEs prepared after an extended mating (21 h) were significantly less able to attract males and to elicit CB. This is the first in depth study of the effect of a single and extended mating on sex pheromone production by a coleopteran species. In the long term, a greater understanding of the regulation of pheromone production could be useful for the manipulation of pest populations.

黄粉虫（Tenebrio molitor L.）的交配行为是由几种信息素介导的，包括一种由雌性产生的雄性引诱剂（R）-（+）-4 - 甲基壬醇（4 - MNol）；一种由雄性产生的雌性引诱剂（Z）-3 - 十二碳烯基乙酸酯；一种由雄性产生的抗催情素；以及至少一种交配信息素。本研究的目的是探究交配对这种复杂信息素系统的影响。通过玻璃棒生物测定法来确定未交配的成年雄性黄粉虫对成年雌性黄粉虫体表提取物的反应，这些雌性黄粉虫包括未交配的雌性、交配一次的雌性（在交配后0、0.5、1或2小时提取）以及长时间交配的雌性（0、1或21小时）。交配导致雌性提取物（FEs）吸引雄性的能力立即受到抑制，但这种抑制是暂时的。由于交配后0.5 - 1小时制备的雌性提取物与未交配雌性的提取物具有相同的吸引力，所以这种抑制作用消退得相对较快。交配2小时后，观察到吸引力再次受到抑制，这可能是由于4 - MNol的滴度下降所致。气相色谱分析证实，交配后4 - MNol的水平下降，从每只未交配雌性约40纳克降至交配雌性中低于我们的检测水平。单次交配事件或1小时的长时间交配并没有显著影响雌性提取物引发雄性交配行为（CB）的能力。然而，长时间交配（21小时）后制备的雌性提取物吸引雄性和引发交配行为的能力显著降低。这是首次深入研究单次和长时间交配对鞘翅目昆虫性信息素产生的影响。从长远来看，更好地理解信息素产生的调控对于害虫种群的控制可能是有用的。