Research Division Agroecology and Environment, Agroscope, Reckenholzstrasse 191, 8046, Zürich, Switzerland.
Research Division Agroecology and Environment, Agroscope, Reckenholzstrasse 191, 8046, Zürich, Switzerland.
Environ Pollut. 2021 Jan 1;268(Pt B):115421. doi: 10.1016/j.envpol.2020.115421. Epub 2020 Aug 15.
Insecticidal Cry proteins from Bacillus thuringiensis (Bt) can be transferred from genetically engineered crops to herbivores to natural enemies. For the lady beetle Harmonia axyridis, we investigated potential uptake of Cry proteins from the gut to the body and intergenerational transfer. Third and fourth instar H. axyridis fed with pollen or spider mites from SmartStax maize contained substantial amounts of Cry1A.105, Cry1F, Cry2Ab2, Cry3Bb1, and Cry34Ab1. Cry protein concentrations in lady beetle larvae were typically one order of magnitude lower than in the food. When H. axyridis larvae were fed Bt maize pollen, median amounts of Cry protein in the non-feeding pupae were below the limit of detection except for small amounts of Cry34Ab1. No Cry protein was detected in pupae when spider mites were used as food. Cry protein concentrations decreased quickly after H. axyridis larvae were transferred from pollen or spider mites to Bt-free food. Aphids contained very low or no detectable Cry protein, and no Cry protein was found in H. axyridis larvae fed with aphids, and in pupae. When H. axyridis adults were fed with Bt maize pollen (mixed with Ephestia kuehniella eggs), the median concentrations of Cry proteins in lady beetle eggs were below the limit of detection except for Cry34Ab1 in eggs laid later in adult life. No Bt protein was detected in eggs laid by H. axyridis females fed with aphids from Bt maize. Our results confirm previous observations that Cry proteins are degraded and excreted quickly in the arthropod food web without evidence for bioaccumulation. Despite the fact that small amounts of Cry proteins were detected in some samples of the non-feeding pupal stage of H. axyridis as well as in eggs, we conclude that this route of exposure is unlikely to be significant for predators or parasitoids in a Bt maize field.
苏云金芽孢杆菌（Bt）的杀虫晶体蛋白可以从基因工程作物转移到草食动物和天敌身上。对于异色瓢虫（Harmonia axyridis），我们研究了其从肠道吸收 Cry 蛋白并在世代间传递的可能性。用 SmartStax 玉米花粉或红蜘蛛喂养的三龄和四龄异色瓢虫幼虫体内含有大量的 Cry1A.105、Cry1F、Cry2Ab2、Cry3Bb1 和 Cry34Ab1。Cry 蛋白在异色瓢虫幼虫体内的浓度通常比食物中的低一个数量级。当异色瓢虫幼虫以 Bt 玉米花粉为食时，非摄食蛹中的 Cry 蛋白含量中位数除少量 Cry34Ab1 外均低于检测限。当以红蜘蛛为食时，蛹中未检测到 Cry 蛋白。当异色瓢虫幼虫从花粉或红蜘蛛转移到不含 Bt 的食物后，Cry 蛋白浓度迅速下降。蚜虫体内 Cry 蛋白含量极低或无法检测到，而以蚜虫为食的异色瓢虫幼虫以及蛹体内均未检测到 Cry 蛋白。当异色瓢虫成虫以 Bt 玉米花粉（与粉纹夜蛾卵混合）为食时，除后期成虫产卵中的 Cry34Ab1 外，成虫产卵中 Cry 蛋白的浓度中位数均低于检测限。从 Bt 玉米上取食的异色瓢虫雌虫所产卵中未检测到 Bt 蛋白。我们的研究结果证实了先前的观察结果，即在节肢动物食物网中，Cry 蛋白会迅速降解和排泄，没有证据表明其生物积累。尽管在异色瓢虫非摄食蛹以及卵的一些样本中检测到少量的 Cry 蛋白，但我们的结论是，对于 Bt 玉米田间的捕食者或寄生蜂来说，这种暴露途径不太可能具有重要意义。
