iES Landau, Institute for Environmental Sciences, RPTU Kaiserslautern-Landau, Fortstraße 7, D-76829, Landau, Germany.
Bull Environ Contam Toxicol. 2023 Mar 24;110(4):70. doi: 10.1007/s00128-023-03708-6.
The biocide Bacillus thuringiensis var. israelensis (Bti) is applied to wetlands to control nuisance by mosquitoes. Amphibians inhabiting these wetlands can be exposed to Bti multiple times, potentially inducing oxidative stress in developing tadpoles. For biochemical stress responses, ambient water temperature plays a key role. Therefore, we exposed tadpoles of the European common frog (Rana temporaria) three times to field-relevant doses of Bti in outdoor floodplain pond mesocosms (FPM) under natural environmental conditions. We sampled tadpoles after each Bti application over the course of a 51-day experiment (April to June 2021) and investigated the activity of the glutathione-S-transferase (GST) and protein carbonyl content as a measure for detoxification activity and oxidative damage. GST activity increased over the course of the experiment likely due to a general increase of water temperature. We did not observe an effect of Bti on either of the investigated biomarkers under natural ambient temperatures. However, Bti-induced effects may be concealed by the generally low water temperatures in our FPMs, particularly at the first application in April, when we expected the highest effect on the most sensitive early stage tadpoles. In light of the global climate change, temperature-related effects of pesticides and biocides on tadpoles should be carefully monitored - in particular since they are known as one of the factors driving the worldwide decline of amphibian populations.
杀生物剂苏云金芽孢杆菌以色列变种 (Bti) 被应用于湿地以控制蚊子的滋扰。栖息在这些湿地中的两栖动物可能会多次接触到 Bti，这可能会导致发育中的蝌蚪产生氧化应激。对于生化应激反应，环境水温起着关键作用。因此，我们在自然环境条件下，将欧洲普通蛙 (Rana temporaria) 的蝌蚪在户外漫滩池塘中进行了三次暴露于与现场相关剂量的 Bti 的实验 (2021 年 4 月至 6 月)。在 51 天的实验过程中，我们在每次 Bti 应用后取样蝌蚪，并研究了谷胱甘肽-S-转移酶 (GST) 的活性和蛋白质羰基含量，作为解毒活性和氧化损伤的衡量标准。GST 活性随着实验的进行而增加，这可能是由于水温的普遍升高。在自然环境温度下，我们没有观察到 Bti 对这两种生物标志物中的任何一种产生影响。然而，Bti 诱导的影响可能被我们的 FPM 中普遍较低的水温所掩盖，特别是在 4 月的第一次应用中，我们预计对最敏感的早期蝌蚪会产生最大的影响。鉴于全球气候变化，应仔细监测杀虫剂和杀生物剂对蝌蚪的温度相关影响 - 特别是因为它们被认为是导致全球两栖动物种群减少的因素之一。
