Bugs management requires a landscape-scale approach

The management of stink bugs in soybean-corn crop rotation systems needs to move from the field scale to the landscape scale. This recommendation appears in a study authored by Weidson Plauter Sutil, Antônio Ricardo Panizzi, and Adeney de Freitas Bueno. The study states that the rotation between soybeans in the summer and corn in the second crop provides a continuous food source for stink bugs. This process forms "green bridges" and favors outbreaks of Pentatomidae in Neotropical agroecosystems.

Researchers advocate monitoring and management throughout the entire production system. Infestation in a crop is influenced by neighboring areas, successive crops, crop residues, weeds, and volunteer soybeans. Therefore, the stink bug should be treated as a pest of the system, not just as a pest of a single crop.

Control in soybeans

In soybeans, control should only occur during the reproductive stage, from R3 to R6, when the population reaches or exceeds the action threshold. In Brazil, the reference cited in the study corresponds to two stink bugs larger than 0,5 centimeters per meter of row in grain crops. For seed fields, the limit drops to one stink bug per meter.

The application of insecticides based on action level reduced the use of these products by an average of 46,6 percent, compared to producers without this criterion. In data from ten harvests in Paraná, the adoption of integrated pest management reduced spraying against stink bugs between 26,3 percent and 66,2 percent, depending on the harvest analyzed.

Diceraeus' advance

The study highlights the progress of Diceraeus furcatus and Diceraeus melacanthus in soybean-corn systems. The participation of Diceraeus spp. population increased from 3,7 percent in the 2014/2015 crop season to 26,3 percent in the 2024/2025 crop season, according to samples taken from soybean fields in Paraná. The increase exceeded 700 percent in ten years.

The brown stink bug, Euschistus heros, while still considered a major species in soybean cultivation, the green stink bug has gained relevance in crop rotation systems. No-till farming, crop residue, and intensive land use provide shelter in the soil. This behavior reduces the insects' contact with insecticides and makes control more difficult.

Late applications

Researchers state that late applications of insecticides to soybeans, at stages R7 and R8, do not protect corn planted after harvest. In these situations, the recommendation involves more tolerant corn hybrids, rapid initial growth, and seed treatment with recommended insecticides.

Soybean harvesting is also part of crop management. Grains lost in the soil, volunteer plants, and weeds serve as food until corn emerges. The review cites average losses of 4 to 6 percent of grains during harvesting in the Neotropics. In Brazil, this volume can represent from 885 to more than one million volunteer soybean plants per hectare, according to the estimate presented by the researchers.

Control in corn

In corn, seedlings are at greatest risk between emergence and the V5 stage. Chemical spraying may still be used in management during outbreaks of Diceraeus spp. reach or exceed three bed bugs per meter during the initial stages, up to V5 to V7.

The review also highlights the use of tolerant plants, biological control, and innovative tools. Soybean cultivars with Block technology show less damage from stink bugs. In corn, hybrids with early vigor, rapid growth, a more rigid stalk, and greater recovery capacity reduce losses.

Among the biological agents, the egg parasitoid telenomus podisi appears as an alternative to Euschistus heros and Diceraeus melacanthus. The study cites releases of approximately 6 parasitoids per hectare, carried out two to three times, with a 14-day interval. Entomopathogenic fungi, such as beauveria bassiana, Metarhikum anisopliae and Cordyceps fumosorosea, are also part of the set of options.

Scientists say that no single tool solves the problem. The most consistent management combines action level planning, monitoring, crop loss reduction, weed control, use of tolerant cultivars, seed treatment, biological control, and selective insecticides when necessary.

Further information can be found at doi.org/10.3390/agronomy16111087