State Key Laboratory of Biocontrol, School of Life Sciences/School of Ecology, Sun Yat-sen University, Guangzhou, 510275, China.
BMC Genomics. 2020 Jan 14;21(1):44. doi: 10.1186/s12864-020-6452-0.
Ladybird beetles (Coleoptera, Coccinellidae) are highly diverse in their feeding habits. Most of them are specialist feeders, while some can have a broad spectrum of prey. As a representative group of generalists, the tribe Coccinellini includes many aphidophagous species, but members of this tribe also feed on other hemipterous insects including coccids, psyllids and whiteflies. As a result, several species are effective biological control agents or invasive species with serious non-target effects. Despite their economic importance, relatively little is known about how they adapt to new prey.
In this study, comparisons of the life history traits and transcriptomes of ladybirds fed initial (aphids) and alternative prey (mealybugs) were performed in three Coccinellini species. The use of alternative prey greatly decreased performance, implied by the significantly prolonged development time and decreased survival rate and adult weight. Prey shifts resulted in a set of differentially expressed genes encoding chemosensory proteins and digestive and detoxifying enzymes.
Our results suggest that these generalists do not perform well when they use alternative prey as the sole nutrition source. Although their capacity for predation might have created an opportunity to use varied prey, they must adapt to physiological obstacles including chemosensing, digestion and detoxification in response to a prey shift. These findings challenge the effect of Coccinellini predators on the biological control of non-aphid pests and suggest the possibility of non-target attacks by so-called specialists.
瓢虫（鞘翅目，瓢虫科）在取食习性上具有高度多样性。它们中的大多数是专食性的，而有些则可以有广泛的猎物谱。作为广义捕食者的代表群体，瓢虫族（Coccinellini）包括许多食蚜性物种，但该族的成员也以其他半翅目昆虫为食，包括介壳虫、木虱和粉虱。因此，一些物种是有效的生物防治剂或具有严重非靶标效应的入侵物种。尽管它们具有经济重要性，但对于它们如何适应新的猎物却知之甚少。
在这项研究中，对三种瓢虫（Coccinellini）的生命史特征和转录组进行了比较，这些瓢虫最初（蚜虫）和替代猎物（粉虱）的食物。替代猎物的使用大大降低了表现，表现在发育时间显著延长、存活率和成虫体重降低。猎物的转移导致了一组差异表达的基因，这些基因编码化学感受蛋白和消化和解毒酶。
我们的结果表明，这些广义捕食者在以替代猎物作为唯一营养源时表现不佳。尽管它们的捕食能力为利用不同的猎物创造了机会，但它们必须适应包括化学感觉、消化和解毒在内的生理障碍，以应对猎物的转移。这些发现挑战了瓢虫类捕食者对非蚜虫害虫生物防治的影响，并表明所谓的专家可能会对非靶标产生攻击。
