Department of Entomology, University of California, Riverside, CA 09521, USA.
J Econ Entomol. 2011 Jun;104(3):773-81. doi: 10.1603/ec10362.
Two systemic neonicotinoids, imidacloprid and thiamethoxam, are widely used for residual control of several insect pests in cotton (Gossypium spp.), vegetables, and citrus (Citrus spp.). We evaluated their impact on six species of beneficial arthropods, including four parasitoid species--Aphytis melinus Debach, Gonatocerus ashmeadi Girault, Eretmocerus eremicus Rose & Zolnerowich, and Encarsia formosa Gahan--and two generalist predators--Geocoris punctipes (Say) and Orius insidiosus (Say)--in the laboratory by using a systemic uptake bioassay. Exposure to systemically treated leaves of both neonicotinoids had negative effects on adult survival in all four parasitoids, with higher potency against A. melinus as indicated by a low LC50. Mortality was also high for G. ashmeadi, E. eremicus, and E. formosa after exposure to both compounds but only after 48 h posttreatment. The two predators G. punctipes and O. insidiosus were variably susceptible to imidacloprid and thiamethoxam after 96-h exposure. However, toxicity to these predators may be related to their feeding on foliage and not just contact with surface residues. Our laboratory results contradict suggestions of little impact of these systemic neonicotinoids on parasitoids or predators but field studies will be needed to better quantify the levels of such impacts under natural conditions.
两种系统用新烟碱类杀虫剂，吡虫啉和噻虫嗪，被广泛用于棉花（棉属）、蔬菜和柑橘（柑橘属）中几种害虫的残留防治。我们评估了它们对六种有益节肢动物的影响，包括四种寄生蜂物种——Aphytis melinus Debach、Gonatocerus ashmeadi Girault、Eretmocerus eremicus Rose & Zolnerowich 和 Encarsia formosa Gahan——以及两种通用捕食性昆虫——Geocoris punctipes (Say) 和 Orius insidiosus (Say)——在实验室中通过系统吸收生物测定法。接触两种新烟碱类化合物的系统处理叶片对所有四种寄生蜂的成虫存活率都有负面影响，其中对 A. melinus 的毒力较低，LC50 较低。接触两种化合物后，G. ashmeadi、E. eremicus 和 E. formosa 的死亡率也很高，但仅在处理后 48 小时。两种捕食性昆虫 G. punctipes 和 O. insidiosus 在接触 96 小时后对吡虫啉和噻虫嗪的敏感性不同。然而，这些捕食性昆虫的毒性可能与其取食叶片有关，而不仅仅是与表面残留物接触有关。我们的实验室结果与这些系统用新烟碱类杀虫剂对寄生蜂或捕食性昆虫影响不大的说法相矛盾，但需要进行田间研究才能更好地量化在自然条件下这些影响的水平。
