Schuehly Wolfgang, Riessberger-Gallé Ulrike, Hernández López Javier
Department of Biology, University of Graz, Universitätsplatz 2, A-8010 Graz, Austria.
Department of Biology, University of Graz, Universitätsplatz 2, A-8010 Graz, Austria.
Ecotoxicol Environ Saf. 2021 Nov 29;228:113020. doi: 10.1016/j.ecoenv.2021.113020.
We were intrigued by reported observations of reduced brood production and a high number of empty brood cells in bee colonies exposed to sublethal pesticide doses, which could suggest an active removal of larvae. Higher numbers of oenocytes, insect cells responsible for lipid processing and detoxification, were also found in pesticide-exposed larvae. Oenocytes are involved in hydrocarbon metabolism and chemical communication, and we hypothesized that these larvae could display altered cuticular hydrocarbon (CHC) profiles when exposed to pesticides as compared to control larvae. In addition, we proposed that these chemical cues could trigger specific behavioral responses in colony nurses. To test these hypotheses, we analyzed the CHC profiles of artificially reared larvae that had been fed sublethal doses of either dimethoate or clothianidin or fed on lipopolysaccharide (LPS) using gas chromatography-mass spectrometry. We found significant differences in the CHC profiles of these differently treated larvae. In a subsequent behavioral experiment, we transferred clothianidin-treated or LPS-treated larvae into the brood combs of surrogate colonies. Larvae that had been fed either the pesticide or LPS were removed at a significantly higher rate than control larvae. Our results demonstrate that larvae exposed to clothianidin possess altered CHC profiles, are detected in the colony by nurse bees via chemical cues and are actively removed.
在接触亚致死剂量农药的蜂群中，育雏产量降低且有大量空育雏细胞，这可能表明幼虫被主动清除。在接触农药的幼虫中还发现了更多的oenocytes，即负责脂质加工和解毒的昆虫细胞。Oenocytes参与碳氢化合物代谢和化学通讯，我们推测与对照幼虫相比，这些幼虫在接触农药时可能会表现出改变的表皮碳氢化合物（CHC）谱。此外，我们提出这些化学信号可能会触发蜂群保育蜂的特定行为反应。为了验证这些假设，我们使用气相色谱 - 质谱分析法分析了人工饲养的幼虫的CHC谱，这些幼虫被喂食了亚致死剂量的乐果或噻虫胺，或者喂食了脂多糖（LPS）。我们发现这些不同处理的幼虫的CHC谱存在显著差异。在随后的行为实验中，我们将噻虫胺处理过的或LPS处理过的幼虫转移到替代蜂群的育雏巢脾中。喂食过农药或LPS的幼虫被清除的速率明显高于对照幼虫。我们的结果表明，接触噻虫胺的幼虫具有改变的CHC谱，通过化学信号被保育蜂在蜂群中检测到并被主动清除。
