Diversity of Stink Bug Adults and Their Parasitoids in Soybean Crops in Brazil: Influence of a Latitudinal Gradient and Insecticide Application Intensity.

Abstract

Over the last 50 yr, the geographical distribution of soybean crop production in Brazil has expanded from the southern region to Maranhão state in the north. We evaluated if this latitudinal expansion affected the community of stink bugs (Hemiptera: Pentatomidae) and their parasitoids. The fauna of stink bugs and their adult parasitoids were studied in nine soybean production regions in Brazil. Stink bugs were sampled using a shake cloth and and held in laboratory cages with natural diet to await emergence of parasitoids. Stink bug and parasitoid species composition did not shift along the latitudinal gradient. Euschistus heros (Fabricius, 1798) (Hemiptera: Pentatomidae) was the most abundant stink bug and occurred in all sampling regions. Hexacladia smithii Ashmead, 1891 (Hymenoptera: Encyrtidae), Cylindromyia brasiliana (Townsend, 1927), Ectophasiopsis sp., Eutrichopoda sp., Gymnoclytia sp., Phasia sp., and Trichopoda sp. (Diptera: Tachinidae) were the parasitoid adult stink bugs that we registered. Parasitism indexes were low, ranging from 0.77 to 6.05% through the regions. On the other hand, parasitism rates were higher in areas with reduced insecticide application in comparison to areas with intensive insecticide use.