Traugott M, Bell J R, Raso L, Sint D, Symondson W O C
Cardiff School of Biosciences, Biomedical Sciences Building, Cardiff University, Museum Avenue, Cardiff CF10 3AX, UK.
Bull Entomol Res. 2012 Apr;102(2):239-47. doi: 10.1017/S0007485311000551. Epub 2011 Oct 10.
Generalist predators and parasitoids are considered to be important regulators of aphids. The former not only feed on these pests, but might also consume parasitoids at all stages of development. This direct or coincidental interference affects the natural control of aphids, the scale of which is largely unknown, and it has rarely been examined under natural conditions. Here, molecular diagnostics were used to track trophic interactions in an aphid-parasitoid-generalist predator community during the build-up of a cereal aphid population. We found that generalist predators, principally carabid and staphylinid beetles as well as linyphiid spiders, had strong trophic links to both parasitoids and aphids. Remarkably, more than 50% of the parasitoid DNA detected in predators stems from direct predation on adult parasitoids. The data also suggest that coincidental intraguild predation is common too. Generalist predators, hence, disrupt parasitoid aphid control, although the levels at which the predators feed on pests and parasitoids seem to vary significantly between predator taxa. Our results suggest that taxon-specific trophic interactions between natural enemies need to be considered to obtain a more complete understanding of the route to effective conservation biological control.
多食性捕食者和寄生蜂被认为是蚜虫的重要调控者。前者不仅以这些害虫为食，还可能在寄生蜂发育的各个阶段将其捕食。这种直接或偶然的干扰影响了对蚜虫的自然控制，其影响程度在很大程度上未知，而且在自然条件下很少被研究。在这里，我们利用分子诊断技术追踪了在谷物蚜虫种群增长期间，蚜虫 - 寄生蜂 - 多食性捕食者群落中的营养相互作用。我们发现，多食性捕食者，主要是步甲科和隐翅虫科甲虫以及微蛛科蜘蛛，与寄生蜂和蚜虫都有很强的营养联系。值得注意的是，在捕食者体内检测到的超过50%的寄生蜂DNA来自对成年寄生蜂的直接捕食。数据还表明，偶然的集团内捕食也很常见。因此，多食性捕食者会破坏寄生蜂对蚜虫的控制，尽管捕食者取食害虫和寄生蜂的程度在不同捕食者类群之间似乎有很大差异。我们的结果表明，为了更全面地理解有效保护生物防治的途径，需要考虑天敌之间特定类群的营养相互作用。
