Intraguild interaction involving Spodoptera spp. and characterization of larval movement of Spodoptera eridania (Cramer) (Lepidoptera: Noctuidae) in Bt and non Bt soybean

Abstract

Soybean [Glycine max L. (Merril)] is considered an agricultural commodity, with high productivity and strong participation in Brazilian exports. However, the pest attack reduces a significant portion of their productivity. The species Spodoptera eridania Cramer, S. frugiperda G.E. Smith and S. cosmioides Walker (Lepidoptera Noctuidae), previously considered secondary pests, currently have caused significant damage in the main producing areas of this oleaginous, attracting the attention of growers and the scientific community. Factors such as the uninterrupted succession of crops involving soybeans, corn and cotton, combined with the presence of weeds in the adjacent areas and the low efficiency of certain insecticides and Cry1Ac protein (Bt crops) have favored the population increase and the yield losses associated with these three species. Given this scenario, it becomes important to better understand the interaction of these lepidopteran pests in conventional and Bt soybean crops, in order to minimize their impact on grain yield of this legume as well as support the choice of the most suitable strategies within of IPM principles. This work proposes to evaluate the intraguild interactions involving S. eridania, S. cosmioides and S. frugiperda and characterize the larval movement of S. eridania in Bt and conventional soybeans and was divided into three steps. At first, they will be performed intraguild interaction assays involving these species, in order to document behavioral aspects (Ethovision) and performance of insects in different competition scenarios. Thus, we will create 21 interaction scenarios (intra- and interspecific) involving large (fifth instar) and small (third instar) species larvae. In the second stage will be carried out assays in greenhouse (FCA / UNESP) and field (possibly at the University of Nebraska - Lincoln) in order to characterize the larval movement of S. eridania "on plant" in conventional and Bt soybeans. In the last phase, the "plant to plant" larval movement in conventional (possibly at the University of Nebraska - Lincoln) and Bt soybean (FCA / UNESP) will be characterized. (AU)