Abstract：
Most field corn in the United States receives a neonicotinoid seed treatment for the management of early-season, soil-dwelling insect pests. Grubs of Maladera formosae (Brenske) (Coleoptera: Scarabaeidae) have been reported feeding on young field corn with both low and high rates of clothianidin seed treatments in Indiana, Michigan, and Ohio. Anecdotally, these infestations are restricted to sandy soils in the region. The purpose of this study was to (1) evaluate whether grub populations in corn are restricted to sandy soils, (2) assess whether soil type influences M. formosae survival, and (3) determine whether soil type affects clothianidin uptake by the plant, possibly explaining the observed differences in M. formosae abundance by soil type. We observed nearly 10-times more grubs in sand (>80% sand content) than loam (<80% sand content) soil within a single corn field. Grub survival to adult was not influenced by soil type. We then compared the concentrations of clothianidin seed treatment in the roots and shoots of corn seedlings grown in either sand or loam soil over time. Similar amounts of the active ingredient were found in the roots and shoots of corn grown in both soil types. Within 2 week, the clothianidin concentrations in both soil types had significantly declined in roots and shoots and were no different from the no-insecticide control. These findings suggest that factors other than insecticide exposure contribute to the higher abundance of M. formosae larvae in sand relative to loam soils, even within the same field.
摘要：
美国大多数田地玉米都接受了新烟碱类种子处理，用于早季管理，土壤害虫。据报道，在印第安纳州，Maladeraformosae（Brenske）的灌木丛（鞘翅目：Scarabaeidae）以幼小的田间玉米为食，并以低比率和高比率的clothianidin种子处理为食，密歇根州,俄亥俄州。有趣的是，这些侵扰仅限于该地区的沙质土壤。这项研究的目的是（1）评估玉米中的grub种群是否仅限于沙质土壤，(2)评估土壤类型是否会影响Formosae的存活，(3)确定土壤类型是否影响植物对噻虫胺的吸收，可能解释了按土壤类型观察到的台湾M.在单个玉米田中，我们观察到的沙子（>80％的沙子含量）比壤土（<80％的沙子含量）多10倍。Grub对成虫的存活不受土壤类型的影响。然后，我们比较了在沙土或壤土中生长的玉米幼苗的根和芽中的噻虫胺种子处理浓度。在两种土壤类型中生长的玉米的根和芽中发现了相似量的活性成分。2周内,两种土壤类型中的噻虫胺浓度在根和芽中均显着下降，与无杀虫剂控制没有差异。这些发现表明，相对于壤土，除杀虫剂暴露外，其他因素导致沙子中的台湾M.幼虫的丰度更高，即使在同一个领域。
