Accumulating evidence in the literature suggests that oleic acid functions as a necromone across widely divergent insect taxa. The prevelance of this phenomenon has not been fully explored, and its application to pest management remains underdeveloped. Khapra beetle (KB), Trogoderma granarium, is a pest of stored grains, with larvae that can enter facultative diapause and remain cryptic in warehouses. Here, we examine how death affects oleic acid content of Trogoderma spp. cuticular extracts, and whether the compound causes a behavioral response. To assess the generalizability of patterns, many experiments were repeated with warehouse beetle (WB), Trogoderma variabile, and larger cabinet beetle (LCB), Trogoderma inclusum. Extracts of larvae that were first killed by being frozen had greater oleic acid content than those derived from live insects. Two-choice behavioral assays compared responses of solvent controls to these extracts, at both low (~ 2 µg) and high (68–131 µg) oleic acid content. The natural extracts also contained cuticular hydrocarbons and other unidentified chemicals. High oleic acid in the extracts repelled the larvae of all three species. Lower levels of oleic acid did not affect KB and LCB movement, but were attractive to WB. We also performed the assay using a large range of doses of oleic acid alone. At the lower doses, oleic acid had no effect on movement, but it became strongly repellant at higher doses, beginning at 100 µg. These results indicate that necromones may be an overlooked aspect of stored product insect biology, which if further researched could improve pest management.

中文翻译：

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冷冻的Trogoderma spp释放出的油酸。幼虫引起特定的行为厌恶

文献中越来越多的证据表明，油酸在广泛不同的昆虫类群中起坏死酮的作用。这种现象的前途尚未得到充分探索，其在病虫害防治中的应用仍未得到开发。Trogoderma granarium的Khapra甲虫（KB）是一种储存谷物的害虫，其幼虫会进入兼性滞育并在仓库中保持隐秘状态。在这里，我们研究了死亡如何影响Trogoderma spp的油酸含量。皮提取物，以及该化合物是否引起行为反应。为了评估模式的通用性，对仓库甲虫（WB），Trogoderma variabile和较大的橱柜甲虫（LCB），Trogoderma inclusum重复了许多实验。首先被冷冻杀死的幼虫提取物的油酸含量高于活昆虫。两种选择的行为分析比较了油酸含量低（〜2 µg）和油酸高（68-131 µg）时溶剂对照对这些提取物的响应。天然提取物还含有表皮碳氢化合物和其他未确认的化学物质。提取物中的高油酸可驱除所有三个物种的幼虫。较低的油酸水平不会影响KB和LCB的运动，但对WB具有吸引力。我们还使用大剂量的油酸进行了测定。在较低的剂量下，油酸对运动没有影响，但从100 µg开始，在较高的剂量下它具有强烈的驱避性。这些结果表明，坏死分子可能是储藏产品昆虫生物学中一个被忽视的方面，