PDF(Pubmed)
Abstract：
Chironomid (Diptera: Chironomidae) larvae play a key role in aquatic food webs as prey for predators like amphibian and dragonfly larvae. This trophic link may be disrupted by anthropogenic stressors such as Bacillus thuringiensis var. israelensis (Bti), a biocide widely used in mosquito control. In a companion study, we recorded a 41% reduction of non-target larval chironomids abundance in outdoor floodplain pond mesocosms (FPMs) treated with Bti. Therefore, we examined the diet of two top predators in the FPMs, larvae of the palmate newt (Salamandridae: Lissotriton helveticus) and dragonfly (Aeshnidae: predominantly Anax imperator), using bulk stable isotope analyses of carbon and nitrogen. Additionally, we determined neutral lipid fatty acids in newt larvae to assess diet-related effects on their physiological condition. We did not find any effects of Bti on the diet proportions of newt larvae and no significant effects on the fatty acid content. We observed a trend in Aeshnidae larvae from Bti-FPMs consuming a higher proportion of large prey (Aeshnidae, newt, damselfly larvae; ~42%), and similar parts of smaller prey (chironomid, mayfly, Libellulidae, and zooplankton), compared to controls. Our findings may suggest bottom-up effects of Bti on aquatic predators but should be further evaluated, for instance, by using compound-specific stable isotope analyses of fatty acids or metabarcoding approaches.
摘要：
Chironomid（双翅目：Chironomidae）幼虫在水生食物网中发挥关键作用，作为两栖动物和蜻蜓幼虫等捕食者的猎物。这种营养联系可能会被人为应激源例如苏云金芽孢杆菌var破坏。以色列（Bti），一种广泛用于灭蚊的杀生物剂。在同伴研究中，我们记录了用Bti处理的室外洪泛区池塘mesocosms（FPM）中非目标幼虫的数量减少了41％。因此,我们检查了FPMs中两个顶级捕食者的饮食，palmate的幼虫（Salamandridae：Lissotritonhelveticus）和蜻蜓（Aeshnidae：主要是Anaximperator），使用碳和氮的大量稳定同位素分析。此外,我们测定了new幼虫的中性脂质脂肪酸，以评估饮食对其生理状况的影响。我们没有发现Bti对new幼虫的饮食比例有任何影响，对脂肪酸含量也没有显着影响。我们观察到来自Bti-FPMs的eshnidae幼虫消耗更高比例的大型猎物的趋势（eshnidae，newt,豆娘幼虫；~42%)，和类似的较小猎物的部分(手，mayfly,Libellulidae,和浮游动物)，与对照组相比。我们的发现可能表明Bti对水生捕食者的自下而上的影响，但应该进一步评估，例如,通过使用脂肪酸的化合物特异性稳定同位素分析或代谢编码方法。
