The effect of Japanese beetle (Popillia japonica) injury in soybean: Is control justifiable?

The Japanese beetle was first detected in New Jersey in 1916 and has successfully spread to most states in the eastern United States. The Japanese beetle can feed on a wide array of plants with at least 300 species in 79 families being documented as hosts. Estimated costs for management of Japanese beetles reach $460 million annually. Specifically, the Japanese beetle is a defoliating pest of soybean. A 2009 and 2010 research study, funded by the Illinois Soybean Association, sampled Japanese beetle abundance, plant-injury, and yield-loss in soybean fields. Sweep samples and leaves were taken from both the interior and edge of soybean fields to estimate abundance and defoliation, respectively. These characteristics were then used to characterize potential yield-loss. Populations of Japanese beetles were significantly higher along the edge especially where corn was the border crop versus the interior of soybean fields. Understanding Japanese beetle populations and corresponding injury will help determine if insecticidal control is justifiable.