The soybean leafminer, Odontota horni, is a minor pest of soybean. This beetle seems to be fairly common in soybean this spring because reports of this insect have come in from eastern, central, and southwestern Iowa. The adult soybean leafminer is approximately 6 mm in length and bright red with a narrow black stripe extending down the back between the wing covers. The antennae, head, and legs also are black.
|Adult soybean leaf miner, Odontota horni..
The larvae mine the leaves, creating a pocket, or blister-like injury, between the upper and lower leaf surfaces. The adults overwinter in protected areas, probably using the same habitat as bean leaf beetles. Soybean leafminer is thought to have one generation per year.
Soybean leafminers are not known to cause economic damage to soybean. They are most commonly found along field margins. The adult beetles scrape and chew leaf tissue, causing a skeletonizing-type of defoliation. Soybean should grow out of any feeding injury caused by the adult beetles and control with insecticides solely for this insect is probably not justified. However, the beetles can transmit bean pod mottle virus. Brent Werner, an undergraduate student at Iowa State University, found last year that soybean leafminers were effective vectors of this soybean pathogen. His research indicated that 80 percent of the soybean plants fed upon by this insect in the laboratory became infected with bean pod mottle virus. The significance of this finding is that soybean leafminers can contribute to the spread of this pathogen in soybean fields. Any management tactics applied to soybean for management of bean leaf beetle also should effectively control soybean leafminer.
This article originally appeared on page 102 of the IC-488(13) -- June 17, 2002 issue.