Data from: Na+/K+-ATPase resistance and cardenolide sequestration: basal adaptations to host plant toxins in the milkweed bugs (Hemiptera: Lygaeidae: Lygaeinae)

Despite sequestration of toxins being a common coevolutionary response to plant defence in phytophagous insects, the macroevolution of the traits involved is largely unaddressed. Using a phylogenetic approach comprising species from four continents, we analysed the ability to sequester toxic cardenolides in the hemipteran subfamily Lygaeinae, which is widely associated with cardenolide-producing Apocynaceae. In addition, we analysed cardenolide resistance of their Na+/K+-ATPases, the molecular target of cardenolides. Our data indicate that cardenolide sequestration and cardenolide-resistant Na+/K+-ATPase are basal adaptations in the Lygaeinae. In two species that shifted to non-apocynaceous hosts, the ability to sequester was secondarily reduced, yet Na+/K+-ATPase resistance was maintained. We suggest that both traits evolved together and represent major coevolutionary adaptations responsible for the evolutionary success of lygaeine bugs. Moreover, specialization on cardenolides was not an evolutionary dead end, but enabled this insect lineage to host shift to cardenolide-producing plants from distantly related families.尽管毒素储积（toxin sequestration）是植食性昆虫应对植物防御的常见协同进化响应，但相关性状的宏观进化却在很大程度上未被深入探究。本研究采用涵盖四大洲物种的系统发育分析方法，对广泛与产强心甾内酯（cardenolides）的夹竹桃科（Apocynaceae）植物相关联的半翅目长蝽亚科（Lygaeinae）昆虫的有毒强心甾内酯储积能力开展了分析。此外，我们还针对其钠钾ATP酶（Na+/K+-ATPase）——强心甾内酯的分子作用靶标——的强心甾内酯抗性进行了检测。研究数据表明，强心甾内酯储积能力与抗强心甾内酯的钠钾ATP酶均为长蝽亚科的基础适应性性状。在两种转向非夹竹桃科寄主植物的物种中，其强心甾内酯储积能力发生了次生减弱，但钠钾ATP酶的抗性仍得以保留。我们认为这两类性状协同演化，是驱动长蝽亚科昆虫演化成功的关键协同适应性性状。此外，专门取食强心甾内酯植物的生存策略并非演化上的死胡同，反而使得该昆虫支系能够转向亲缘关系较远的产强心甾内酯植物类群作为寄主。