Field Cage Assessment of Feeding Damage by Riptortus pedestris on Soybeans in China

SIMPLE SUMMARY: Riptortus pedestris (Fabricius) is a serious pest of soybeans. The nymphs and adults of R. pedestris cause feeding injury to soybean pods, resulting in significant field damage losses. In this paper, we tested the damage to soybeans at different growth stages caused by different densities of R. pedestris, through the field cage test. Our results showed that R(4) was the most sensitive stage to R. pedestris injury. The damage intensity of the soybeans increased with increased pest density, and soybean nutrition factors changed after suffering R. pedestris injury. These results will be beneficial to future management programs of R. pedestris in soybean fields. ABSTRACT: The bean bug, Riptortus pedestris, is a major pest of soybeans. In order to assess the critical stages of soybean damage by R. pedestris, we tested the damage to soybeans at different growth stages (R(2), R(4), and R(6)) caused by five densities of R. pedestris (1, 2, 3, 4, and 5) through a field cage experiment. The results show that the R(4) stage was the most sensitive stage in terms of suffering R. pedestris injury damage, followed by the R(6) stage and then the R(2) stage. The number of stay green leaves was 7.04 per plant, the abortive pod rate of the soybeans was 56.36%, and the abortive seed rate of the soybeans was 46.69%. The dry weight of the soybeans was 14.20 g at the R(4) stage; these values of R(4) were significantly higher than at the R(2) and R(6) stages. However, the dry weight of soybean seed was 4.27 g and the nutrient transfer rate was 27.01% in the R(4) stage; these values were significantly lower than in the R(2) and R(6) stages. The number of stay green leaves, abortive pod rates, and abortive seed rates were all increased significantly with increasing pest density at each stage of soybean growth. However, the nutrient transfer rate was significantly decreased with the increase in the pest density. Soybean nutrition factors changed after they suffered R. pedestris injury; the lipid content of the soybean seed decreased and the lipid content of the soybean plant increased compared to controls, when tested with a density of five R. pedestris in the R(4) stage. These results will be beneficial to the future management of R. pedestris in soybean fields.