Native marsupial acts as an in situ biological control agent of the main soybean pest (Euschistus heros) in the Neotropics

Natural predators of agricultural pests are known to help increase crop yields and are considered an alternative to chemical insecticides. We investigated the role of the gracile mouse opossum Gracilinanus agilis for controlling a soybean pest, the brown stink bug Euschistus heros . We tested the hypothesis that this bug disperses to natural forest environments of the Brazilian savanna (Cerrado) during the soybean off-season and that G . agilis acts as a relevant predator of this insect. We also quantified and valued G. agilis predation on E. heros independently in five forest areas located at different distances from a soybean crop. The isotope ratios ( δ 13 C and δ 15 N) of E. heros remains found in predator fecal samples collected during the soybean off-season were more similar to E. heros collected in the crop than to samples collected during the growing season. Gracilinanus agilis predation on E. heros in forests was greater during the crop off-season than during the growing season but decreased with increasing distance between forest and crop. This inverse relationship indicates that the potential role of mouse opossums for pest control depends on the proximity of natural forests to crops. We estimated that the ecosystem service provided by this marsupial may reach up to US$ 31.08 ha −1 year −1 of native forest, which may represent tens of millions of dollars per year considering the amount of native vegetation within farmlands in the Cerrado. These results highlight the relevance of natural vegetation conservation near crops for the maintenance of agricultural pest control.