Bean leaf beetle and bean pod mottle virus: new research findings in Virginia

The bean leaf beetle (BLB), Ceretoma trifurcata (Förster), is native to the United States and is found primarily in the north central and southeast. It is a pest of soybean, lima bean as well as snap beans. This beetle not only damages foliage, but is also the primary vector of Bean Pod Mottle Virus (Comoviridae)(BPMV). Mild symptoms of the virus include slight chlorotic mottling of the foliage to a severe mosaic with wrinkled leaves and patches of yellow foliage. This virus can cause a severe decrease in pod production if plants are infected early in the growing season. There are two primary inoculum sources of the BPMV in Virginia, which are overwintering viruliferous beetles and perennial infected host plants. Leaf samples as well as overwintering beetles were collected in the spring and an ELISA was performed to check for the presence of virus. No host plants tested positive while 80% of the overwintered beetles were positive for the virus in the spring of 2008. However, when overwintered beetles were collected in the spring of 2009 mechanical transmission of the virus did not occur when beetles were exposed to soybean plants. BPMV has also been found in Northern VA this fall (2009) where the virus was not previously established. Leaf samples were collected from fields in Northern VA as well as on the DELMARVA Peninsula and a tissue blot immunoassay (TBIA) was conducted. Beetles were also collected and an ELISA was preformed to check for the percentage of viruliferous beetles in the fields that tested positive on TBIA.