Department of Entomology, University of Nebraska, Lincoln, NE, USA.
Department of Statistics, University of Nebraska, Lincoln, NE, USA.
J Insect Sci. 2021 Mar 1;21(2). doi: 10.1093/jisesa/ieaa149.
Insecticide exposure has been identified as a contributing stressor to the decline in the North American monarch butterfly Danaus plexippus L. (Lepidoptera: Nymphalidae) population. Monarch toxicity data are currently limited and available data focuses on lethal endpoints. This study examined the 72-h toxicity of two pyrethroid insecticides, bifenthrin and β-cyfluthrin, and their effects on growth and diet consumption. The toxicity of bifenthrin to caterpillars was lower than β-cyfluthrin after 72 h. Survival was the most sensitive endpoint for bifenthrin, but diet consumption and caterpillar growth were significantly reduced at sublethal levels of β-cyfluthrin. Using AgDRIFT spray drift assessment, the aerial application of bifenthrin or β-cyfluthrin is predicted to pose the greatest risk to fifth-instar caterpillars, with lethal insecticide deposition up to 28 m for bifenthrin and up to 23 m for β-cyfluthrin from treated edges of fields. Low boom ground applications are predicted to reduce distances of lethal insecticide exposure to 2 m from the treated field edge for bifenthrin and β-cyfluthrin. Growth and survival of fifth-instar monarch caterpillars developing within the margins of a treated field may be significantly impacted following foliar applications of bifenthrin or β-cyfluthrin. These findings provide evidence that pyrethroid insecticides commonly used for soybean pest control are a potential risk to monarch caterpillars in agricultural landscapes.
杀虫剂暴露已被确定为导致北美帝王蝶 Danaus plexippus L.（鳞翅目：蛱蝶科）数量下降的一个促成压力因素。帝王蝶毒性数据目前有限，可用数据主要集中在致死终点上。本研究检查了两种拟除虫菊酯杀虫剂，联苯菊酯和β-氯氟氰菊酯的 72 小时毒性及其对生长和饮食消耗的影响。联苯菊酯对毛毛虫的毒性在 72 小时后低于β-氯氟氰菊酯。生存是联苯菊酯最敏感的终点，但在亚致死水平的β-氯氟氰菊酯下，饮食消耗和毛毛虫生长显著减少。使用 AgDRIFT 喷雾漂移评估，预测联苯菊酯或β-氯氟氰菊酯的空中应用对五龄毛毛虫构成最大风险，联苯菊酯的致死杀虫剂沉积高达 28 米，β-氯氟氰菊酯高达 23 米，来自处理过的田间边缘。低喷杆地面应用预计将使联苯菊酯和β-氯氟氰菊酯的致死杀虫剂暴露距离从处理过的田间边缘减少到 2 米。在处理过的田间边缘内发育的五龄帝王蝶毛毛虫的生长和生存可能会受到联苯菊酯或β-氯氟氰菊酯叶面施药的显著影响。这些发现提供了证据，表明常用于防治大豆害虫的拟除虫菊酯杀虫剂可能是农业景观中帝王蝶毛毛虫的潜在风险。
