Intraspecific and interspecific interaction and fitness cost of stink bugs Euschistus heros, Diceraeus melacanthus, and Piezodorus guildinii in soybean.

Background: The most common pentatomid species in soybean crops are Euschistus heros (F.), Piezodorus guildinii (W.), and Diceraeus melacanthus (D.), causing a significant reduction in yield. It is known that these stink bugs inhabit the reproductive structures of soybeans simultaneously; however, there are few studies addressing their intraguild interactions, as well as aspects of possible competition between them in plants. Thus, the interspecific and intraspecific interactions of these stink bugs were evaluated in laboratory and field conditions, throughout the duration of the instars and adulthood, including longevity, mortality, and the number of eggs per female.

Results: Euschistus heros had a higher competitive capacity in the interaction with D. melacanthus and P. guildinii, negatively interfering in the abundance or development (duration of instar, fertility, and mortality) of these stink bugs in soybean crops. This interference may act on the natural balance of these insect pests. Mortality of adults in interactions containing E. heros as a competitor or not showed that this species was not affected by the other species under field conditions. In the scenario where D. melacanthus was evaluated, it was observed that the presence of other species caused higher mortality in D. melacanthus. Additionally, higher P. guildiniii mortality was observed in interspecific interactions.

Conclusion: Our results suggest that E. heros has a greater competitive ability in the soybean crop, followed by D. melacanthus and P. guildinii. Therefore, the results found justified the greater abundance of E. heros and helped to explain the increasing occurrence of D. melacanthus in soybean crops, contributing to new directions for understanding the interaction of the soybean stink bug complex. © 2023 Society of Chemical Industry.