Abstract Promecognathus (Carabidae) includes beetles that are specialist predators whose prey are polydesmidan millipedes that produce highly toxic hydrogen cyanide and benzaldehyde as a defense, and it is unknown how Promecognathus overcomes these chemicals. We observed Promecognathus laevissimus (Dejean, 1829) and P. crassus (LeConte, 1868) in the laboratory and found that they did not use behaviors to avoid the chemical defenses of their prey, Xystocheir dissecta (Wood, 1867) (Polydesmida: Xystodesmidae). We tested benzaldehyde as a feeding deterrent and found noticeable deterrence in all carabid beetles tested except Promecognathus species and Metrius contractus (Eschscholtz, 1829). A total of 18 carabid species were exposed to cyanide vapors in an enclosed chamber for 10 min to determine their relative tolerances. Promecognathus and M. contractus were unaffected by HCN exposures 7–15 times greater than quantities that knocked down all other species. Promecognathus laevissimus and M. contractus were then exposed to high levels of HCN for 2 h, and while individuals of M. contractus succumbed, all P. laevissimus were still moving after 2 h. It is possible that Promecognathus evolved a high tolerance to cyanide as part of a suite of adaptations related to millipede predation. However, we have no plausible explanation for the high tolerance in Metrius, for which there is no evidence of millipede feeding. This is the first documented case of predatory insects that exhibit high tolerance and potential resistance to cyanide. Possibly, these beetles have a detoxification mechanism that is not cyanide specific, as their tolerance level far exceeds any dose they would encounter in their natural habitat.

中文翻译：

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Promecognathus 的千足虫捕食行为和 Promecognathus 和 Metrius（鞘翅目：Carabidae）的异常氰化物耐受性

摘要 Promecognathus (Carabidae) 包括甲虫，它们是专门的捕食者，其猎物是多聚甲胨千足虫，可产生剧毒的氰化氢和苯甲醛作为防御，但尚不清楚 Promecognathus 如何克服这些化学物质。我们在实验室观察了 Promecognathus laevissimus (Dejean, 1829) 和 P. crassus (LeConte, 1868)，发现它们并没有使用行为来避免猎物 Xystocheir dissecta (Wood, 1867) (Polydesmida: Xystodemidae) 的化学防御. 我们测试了苯甲醛作为摄食威慑剂，发现除 Promecognathus 物种和 Metrius contractus 外，所有测试的甲虫都有明显的威慑作用 (Eschscholtz, 1829)。总共 18 种carabid 物种在密闭室中暴露于氰化物蒸气10 分钟，以确定它们的相对耐受性。Promecognathus 和 M. 收缩受 HCN 暴露的影响是击倒所有其他物种的数量的 7-15 倍。Promecognathus laevissimus 和 M. contractus 然后暴露于高水平的 HCN 2 小时，虽然 M. contractus 个体死亡，但所有 P. laevissimus 在 2 小时后仍在移动。Promecognathus 可能进化出对氰化物的高度耐受性，作为与千足虫捕食相关的一系列适应的一部分。然而，我们对 Metrius 的高耐受性没有合理的解释，对此没有证据表明有千足虫进食。这是第一个记录在案的捕食性昆虫对氰化物表现出高耐受性和潜在抗性的案例。可能这些甲虫具有非氰化物特异性的解毒机制，