Centro de Protección Vegetal y Biotecnología, Unidad Mixta Gestión Biotecnológica de Plagas, Instituto Valenciano de Investigaciones Agrarias, 46113 Moncada, Spain.
Laboratory of Entomology, Wageningen University, 6700AA Wageningen, The Netherlands.
Proc Natl Acad Sci U S A. 2019 Aug 20;116(34):16817-16822. doi: 10.1073/pnas.1904298116. Epub 2019 Aug 5.
Pest control in agriculture is mainly based on the application of insecticides, which may impact nontarget beneficial organisms leading to undesirable ecological effects. Neonicotinoids are among the most widely used insecticides. However, they have important negative side effects, especially for pollinators and other beneficial insects feeding on nectar. Here, we identify a more accessible exposure route: Neonicotinoids reach and kill beneficial insects that feed on the most abundant carbohydrate source for insects in agroecosystems, honeydew. Honeydew is the excretion product of phloem-feeding hemipteran insects such as aphids, mealybugs, whiteflies, and psyllids. We allowed parasitic wasps and pollinating hoverflies to feed on honeydew from hemipterans feeding on trees treated with thiamethoxam or imidacloprid, the most commonly used neonicotinoids. LC-MS/MS analyses demonstrated that both neonicotinoids were present in honeydew. Honeydew with thiamethoxam was highly toxic to both species of beneficial insects, and honeydew with imidacloprid was moderately toxic to hoverflies. Collectively, our data provide strong evidence for honeydew as a route of insecticide exposure that may cause acute or chronic deleterious effects on nontarget organisms. This route should be considered in future environmental risk assessments of neonicotinoid applications.
农业中的害虫防治主要基于杀虫剂的应用，但这可能会对非靶标有益生物产生影响，导致不良的生态效应。新烟碱类杀虫剂是使用最广泛的杀虫剂之一。然而，它们具有重要的负面副作用，特别是对传粉者和其他以花蜜为食的有益昆虫。在这里，我们确定了一种更易接触的暴露途径：新烟碱类杀虫剂会到达并杀死以 agroecosystems（农业生态系统）中最丰富的昆虫碳水化合物来源——蜜露为食的有益昆虫。蜜露是半翅目昆虫（如蚜虫、粉虱、木虱和叶蝉）吸食韧皮部的排泄产物。我们允许寄生蜂和传粉的食蚜蝇以吸食噻虫嗪或吡虫啉处理过的树木上的半翅目昆虫的蜜露为食，噻虫嗪和吡虫啉是使用最广泛的新烟碱类杀虫剂。LC-MS/MS 分析表明，这两种新烟碱类杀虫剂都存在于蜜露中。噻虫嗪蜜露对这两种有益昆虫都具有高毒性，而吡虫啉蜜露对食蚜蝇具有中度毒性。总的来说，我们的数据为蜜露作为一种杀虫剂暴露途径提供了强有力的证据，这种途径可能对非靶标生物造成急性或慢性的有害影响。在未来对新烟碱类杀虫剂应用的环境风险评估中，应考虑这一途径。
