Management Strategies for the Control of Diceraeus melacanthus (Dallas) in Soybean (Summer)-Maize (Fall/Winter) Successions.

Abstract

The crop system of soybean (summer)-maize (fall/winter) succession has been adopted widely in the Neotropics. It inadvertently provides food to stink bugs between crops, forming "green-bridges," which favor Diceraeus melacanthus (Dallas) outbreaks. Attempts to control these outbreaks, usually occurring at the end of the soybean cycle and the beginning of the maize cycle, were made by spraying insecticides at the time of soybean desiccation in addition to insecticide seed treatment on maize, but apparently it has been insufficient to provide acceptable control. Therefore, this study was carried out in two consecutive seasons (2016 to 2018) to evaluate different management strategies for the control of D. melacanthus at the end of the soybean cycle and the beginning of the maize cycle, a period of time in which major D. melacanthus outbreaks have been frequently recorded. Late stink bug control (insecticide spray at development stage R7 of soybean) significantly reduced pest populations but left insecticide residue in the soybean grains. Pre-harvest desiccation with and without addition of insecticides (also at R7) also reduced pest populations but negatively impacted soybean yield. Seed treatment on maize numerically reduced the number of stink bugs, without significant difference from maize without seed treatment, but still resulting in higher yield. Thus, we conclude that the best of the here evaluated treatments is the adoption of soybean-IPM (Economic Threshold, ET at levels of two stink bugs/m) during soybean pod development/filling (R3 to R6) to guide insecticide use in addition to maize seed treatment.