Australian funnel-web spiders are infamous for causing human fatalities, which are induced by venom peptides known as δ-hexatoxins (δ-HXTXs). Humans and other primates did not feature in the prey or predator spectrum during evolution of these spiders, and consequently the primate lethality of δ-HXTXs remains enigmatic. Funnel-web envenomations are mostly inflicted by male spiders that wander from their burrow in search of females during the mating season, which suggests a role for δ-HXTXs in self-defense since male spiders rarely feed during this period. Although 35 species of Australian funnel-web spiders have been described, only nine δ-HXTXs from four species have been characterized, resulting in a lack of understanding of the ecological roles and molecular evolution of δ-HXTXs. Here, by profiling venom-gland transcriptomes of 10 funnel-web species, we report 22 δ-HXTXs. Phylogenetic and evolutionary assessments reveal a remarkable sequence conservation of δ-HXTXs despite their deep evolutionary origin within funnel-web spiders, consistent with a defensive role. We demonstrate that δ-HXTX-Ar1a, the lethal toxin from the Sydney funnel-web spider Atrax robustus, induces pain in mice by inhibiting inactivation of voltage-gated sodium (Na_V) channels involved in nociceptive signaling. δ-HXTX-Ar1a also inhibited inactivation of cockroach Na_V channels and was insecticidal to sheep blowflies. Considering their algogenic effects in mice, potent insecticidal effects, and high levels of sequence conservation, we propose that the δ-HXTXs were repurposed from an initial insecticidal predatory function to a role in defending against nonhuman vertebrate predators by male spiders, with their lethal effects on humans being an unfortunate evolutionary coincidence.

澳大利亚的漏斗蜘蛛因引起人的致命性而臭名昭著，致命性是由被称为δ-六毒素（δ-HXTXs）的毒肽诱导的。在这些蜘蛛的进化过程中，人类和其他灵长类动物没有出现在猎物或捕食者谱图中，因此δ-HXTXs的灵长类动物致死力仍然难以捉摸。漏斗网的破坏主要是由雄性蜘蛛造成的，它们在交配季节从洞穴中徘徊以寻找雌性，这表明δ-HXTX在自卫中的作用，因为在此期间雄性蜘蛛很少觅食。尽管已描述了35种澳大利亚漏斗蜘蛛，但仅对四种物种中的9种δ-HXTX进行了表征，导致对δ-HXTX的生态作用和分子进化缺乏了解。这里，通过分析10个漏斗网物种的毒腺转录组，我们报告了22个δ-HXTXs。系统发育和进化评估显示，尽管δ-HXTX在漏斗网状蜘蛛内有很深的进化起源，但它具有保守的防御作用。我们证明了δ-HXTX-Ar1a，来自悉尼漏斗网蜘蛛的致命毒素健壮的Atrax通过抑制参与伤害性信号传导的电压门控钠（Na _V）通道的失活而诱导小鼠疼痛。δ-HXTX-Ar1a还抑制了蟑螂Na _V通道的失活，并杀害了蝇blow。考虑到它们对小鼠的促生作用，有效的杀虫作用以及高水平的序列保守性，我们建议将δ-HXTXs从最初的杀虫性捕食功能改用于雄性蜘蛛对非人类脊椎动物捕食者的防御作用及其致命作用人类是不幸的进化巧合。