Bohnenblust Eric, Egan J Franklin, Mortensen David, Tooker John
Department of Entomology, 101 Merkle Bldg., The Pennsylvania State University, University Park, PA 16802, USA.
Environ Entomol. 2013 Jun;42(3):586-94. doi: 10.1603/EN13021.
Herbicides are the most commonly applied pesticides in agroecosystems, and therefore pose potentially significant ecotoxicological risks to plants and insects. Glyphosate is the most common herbicide worldwide, and glyphosate-resistant weeds are quickly becoming serious challenges in some agroecosystems. Because of this resistance epidemic and the recent development of crops with resistance to dicamba or 2,4-D, herbicide-use patterns are likely to change. Presently, dicamba and 2,4-D cause most herbicide-drift damage to nontarget plants despite limited agricultural usage, but the effects of these synthetic auxin herbicides on insects have been poorly explored. To understand the influence of dicamba on insects, we applied several sublethal, drift-level rates of dicamba to soybean, Glycine max L., and Carduus thistle, and measured growth and survival of Helicoverpa zea (Boddie) and Vanessa cardui (L.) larvae, respectively. For thistle, we measured percent nitrogen content before and after dicamba application. We also performed direct toxicity bioassays on the two caterpillar species with several rates of dicamba. Dicamba was not directly toxic to larvae of either species, and H. zea showed no negative effects when feeding on soybeans dosed with dicamba. We did, however, detect significant negative, indirect effects of higher rates of dicamba on V. cardui larval and pupal mass, total nitrogen of thistles post application, and thistle biomass in the presence of V. cardui larvae. Notably, thistle biomass was not related to dicamba dose in absence of larvae. Our results indicate that dicamba can indirectly influence the performance of some caterpillar species, possibly by altering plant nutritional content.
除草剂是农业生态系统中使用最普遍的农药，因此对植物和昆虫构成潜在的重大生态毒理学风险。草甘膦是全球最常见的除草剂，抗草甘膦杂草在一些农业生态系统中迅速成为严峻挑战。由于这种抗性流行以及最近对麦草畏或2,4-滴具有抗性的作物的发展，除草剂的使用模式可能会发生变化。目前，尽管农业使用量有限，但麦草畏和2,4-滴对非靶标植物造成的除草剂漂移损害最大，不过这些合成生长素除草剂对昆虫的影响尚未得到充分研究。为了解麦草畏对昆虫的影响，我们将几种亚致死、漂移水平的麦草畏施用于大豆、大豆属的大豆和飞廉蓟，并分别测量了棉铃虫和小红蛱蝶幼虫的生长和存活情况。对于蓟，我们测量了施用麦草畏前后的氮含量百分比。我们还对这两种毛虫进行了几种麦草畏剂量的直接毒性生物测定。麦草畏对这两种物种的幼虫均无直接毒性，棉铃虫取食施用麦草畏的大豆时未表现出负面影响。然而，我们确实检测到较高剂量的麦草畏对小红蛱蝶幼虫和蛹的质量、施用后蓟的总氮含量以及存在小红蛱蝶幼虫时蓟的生物量有显著的负面间接影响。值得注意的是，在没有幼虫的情况下，蓟的生物量与麦草畏剂量无关。我们的结果表明，麦草畏可能通过改变植物营养成分间接影响某些毛虫物种的生长性能。
