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Ecology and Management of European Corn Borer and Other Lepidopteran Pests of Corn
J. A. White
Department of Entomology
As more and more corn habitat has been planted in Bt, which is toxic to European corn borer, some regions of North America have seen declines in corn borer populations. These new lower populations of corn borer will have different population dynamics over time, including differences in sex ratio and/or disease transmission. Such factors are important to understand because corn borer is likely to remain a pest in organic corn and non-corn crops such as bell pepper.
2011 Project Description
In 2011 we continued to collaborate with Bill Hutchison, University of Minnesota, on his area-wide survey of European corn borer. We again collected European corn borer moths from a light trap in Lexington, Kentucky, and shipped the moths to Dr. Hutchison. Dr. Hutchison in return sent moths from other collection locations to us, so that we could screen for the microsporidian Nosema.
Dr. Hutchison presented the data at an international meeting in Germany in October, and the data is also disseminated to the NC205 group during the annual group meeting. This data is being incorporated into a manuscript that will be submitted to the Journal of Applied Entomology shortly.
We completed Nosema screening on up to 25 moths per location for 16 locations collected in 2009 and 8 locations in 2010. We found that Nosema remained present at all sites (despite reduced moth abundance at some sites) but that prevalence of the microsporidian varied widely from location to location, ranging from 10 to 80% infection.
We have also found a correlation between Nosema prevalence and the sex ratio of moths collected at a site: populations with higher Nosema prevalence tended to have a female biased sex ratio. This pattern was pronounced in 2009, and more muted (but consistent in trend) in 2010. There is a possibility that Nosema may be causative of female bias in the populations, or may be positively correlated with another microbe that induces female bias.
In 2012 we will attempt to collect live moths that are infected, to more thoroughly investigate the sex ratio of infected versus uninfected moths, and to assess the associated microbial community. These results will contribute to an overall understanding of European corn borer population dynamics following area-wide suppression due to widespread adoption of Bt technology, and will complement previously collected information on the non-target effects of Bt technology.