Abstract:
Temperature can interact with chemical pesticides and modulate their toxicity. Sublethal exposure to pesticides is known to trigger hormetic responses in pests. However, the simultaneous effects of temperature and sublethal exposure to single or mixture-based insecticides on the insects\' stimulatory responses are not frequently considered in toxicological studies. Here we investigated the combined effects of temperature on the lethal and sublethal responses of the green peach aphid Myzus persicae after exposure to commercial formulations of a neonicotinoid (thiamethoxam) and a pyrethroid (lambda-cyhalothrin) and their mixture. Firstly, the concentration-response curves of the insecticides were determined under four temperatures (15 °C, 20 °C, 25 °C, and 28 °C) by the leaf dipping method. Subsequently, the sublethal concentrations C0, CL1, CL5, CL10, CL15, CL20, and CL30 were selected to assess sublethal effects on aphids\' longevity and reproduction under the same temperatures. The results showed that the mixture of thiamethoxam + lambda-cyhalothrin caused greater toxicity to aphids compared to the formulations with each active ingredient alone and that the toxicity was higher at elevated temperatures. Furthermore, the exposure to low concentrations of the mixture (thiamethoxam + lambda-cyhalothrin) and the separated insecticides induced stimulatory responses in the longevity and fecundity of exposed aphid females, but the occurrence of such hormetic responses depended on the insecticide type, its sublethal concentration, and the temperature as well as their interactions.
摘要:
温度可以与化学农药相互作用并调节其毒性。已知农药的亚致死性暴露会引发害虫的恐怖反应。然而,毒理学研究中不经常考虑温度和单一或混合杀虫剂亚致死暴露对昆虫刺激反应的同时影响。在这里,我们研究了暴露于新烟碱(噻虫嗪)和拟除虫菊酯(lambda-氯氟氰菊酯)及其混合物的商业制剂后,温度对绿色桃蚜虫的致死和亚致死反应的综合影响。首先,在四个温度(15°C,20°C,25°C,和28°C),采用浸叶法。随后,选择亚致死浓度C0,CL1,CL5,CL10,CL15,CL20和CL30来评估在相同温度下对蚜虫寿命和繁殖的亚致死效应。结果表明,与单独使用每种活性成分的制剂相比,噻虫嗪+λ-氯氟氰菊酯的混合物对蚜虫产生更大的毒性,并且在升高的温度下毒性更高。此外,暴露于低浓度的混合物(噻虫嗪λ-氯氟氰菊酯)和分离的杀虫剂在暴露的蚜虫雌性的寿命和繁殖力中引起的刺激反应,但是这种封闭反应的发生取决于杀虫剂的类型,其亚致死浓度,和温度以及它们之间的相互作用。