Plant Protection Institute, Hebei Academy of Agricultural and Forestry Sciences/IPM Center of Hebei Province/Key Laboratory of Integrated Pest Management on Crops in Northern Region of North China, Ministry of Agriculture and Rural Affairs, P. R. China, Baoding, China.
PLoS One. 2022 Aug 15;17(8):e0272429. doi: 10.1371/journal.pone.0272429. eCollection 2022.
Temperature can have influences on the toxicities and efficacies of insecticides. Therefore, it is important to accurately evaluate the temperature effect (TE) on the toxicities of insecticides to insects. Previous studies have shown that the pre-exposure of insects to temperatures before their contact with insecticides, caused variations in their toxicities. However, most of these studies focused on the TE of the insecticides post-treatment. In this study we hypothesized that pre-exposure time of insect at different temperature can influence the toxicities of insecticides. We then evaluated the influence of different pre-exposure time (0, 2, 4, 8, 12 and 24 h) on toxicities of three different temperature effect insecticides (TEIs) to Apolygus lucorum at 15, 25 and 35°C respectively. We found that all toxicities of three TEIs to A. lucorum did not vary with pre-exposure time at 25°C. The LC50 of hexaflumuron (positive TEI) only decreased (from 1800.06 to 237.40 mg/L) at 15°C, with an increase in the pre-exposure time. Whereas the LC50 of β-cypermethrin (negative TEI) decreased from 225.43 to 60.79 mg/L at 35°C. These results also showed that the temperature coefficients (TCs) of the toxicities were influenced by pre-exposure time at different temperatures. For hexaflumuron, all the TCs at 25°C and 35°C decreased, as the pre-exposure time increased. For β-cypermethrin, the TCs decreased significantly only at 35°C. The toxicity and TCs of phoxim (non-effect TEI) showed no obvious fluctuation at the tested temperatures. These results showed that when the pre-exposure times were extended, the toxicities of the positive / negative TEI showed an increase at the temperature where the pest was less sensitive to the insecticides. These results can be applied to determine the toxicities / bioactivities of different insecticides accurately at different temperatures.
温度会影响杀虫剂的毒性和效果。因此，准确评估温度对昆虫杀虫剂毒性的影响（TE）非常重要。先前的研究表明，昆虫在接触杀虫剂之前暴露于温度下，会导致其毒性发生变化。然而，这些研究大多集中在杀虫剂处理后的 TE 上。在这项研究中，我们假设昆虫在不同温度下的预暴露时间会影响杀虫剂的毒性。然后，我们评估了不同预暴露时间（0、2、4、8、12 和 24 小时）对三种不同温度效应杀虫剂（TEIs）在 15、25 和 35°C 下对桃小食心虫的毒性的影响。我们发现，在 25°C 时，三种 TEIs 对 A. lucorum 的所有毒性均不随预暴露时间而变化。六氟铃脲（正 TEI）的 LC50 仅在 15°C 时随预暴露时间的增加而降低（从 1800.06 降至 237.40 mg/L）。而β-氯氰菊酯（负 TEI）的 LC50 在 35°C 时从 225.43 降至 60.79 mg/L。这些结果还表明，毒性的温度系数（TCs）受不同温度下预暴露时间的影响。对于六氟铃脲，在 25°C 和 35°C 下，所有 TCs 随预暴露时间的增加而降低。对于β-氯氰菊酯，仅在 35°C 时 TCs 显著降低。辛硫磷（非效应 TEI）的毒性和 TCs 在测试温度下没有明显波动。这些结果表明，当预暴露时间延长时，在害虫对杀虫剂较不敏感的温度下，正/负 TEI 的毒性会增加。这些结果可用于准确确定不同温度下不同杀虫剂的毒性/生物活性。
