Orientation and Colonization Preference of Adult Megacopta cribraria (Hemiptera: Plataspidae) to Soybean Development Stages

Kudzu bugs, Megacopta cribraria, a species native to Asia but currently invading U.S. has become a serious pest of soybean crops. Although adults are known to move from wild kudzu patches to infest and develop on early planted soybean plants, the nature of the migration, the specific preferred soybean development stages, and the behavior response from males and females require elucidation. Given choices of soybean plants at four representative development stages, adults preferentially (77% on average distributional proportion) settled on soybean plants at early reproductive stages (R1 and R3) than later reproductive stage (after R3) or early vegetative stage (V2). Specifically, the adults demonstrated significant predilection to R1 during the first hour, then the numbers on R3 sustainably increased over time during the 3-day observation. Y-tube olfactometer bioassay not only showed that the behavioral preferences were influenced by volatile chemicals associated with whole soybean plants but also corroborated the results from greenhouse choice experiments. Interestingly, Y-tube bioassay also indicated that females were significantly more responsive to whole plant volatiles, meaning females were more likely to be colony funders on soybean crop. The empirical data indicate that soybean plants at early reproductive development stages are the most attractive to kudzu bugs.