Effect of age and mating status on adult European corn borer (Lepidoptera: Crambidae) dispersal from small-grain aggregation plots

Authors: Reardon, Brendon; Sappington, Thomas

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/10/2007
Publication Date: 8/1/2007
Citation: Reardon, B., Sappington, T.W. 2007. Effect of age and mating status on adult European corn borer (Lepidoptera: Crambidae) dispersal from small-grain aggregation plots. Journal of Economic Entomology. 100(4):1116-1123.

Interpretive Summary: The European corn borer is a major pest of corn in the U.S. and is often controlled with genetically modified corn hybrids [Bacillus thuringiensis (Bt) corn]. There is concern that this insect may become resistant to Bt corn. If resistance is detected in a population, it has been suggested that mass-releases of Bt-susceptible moths reared in the laboratory to mate with resistant moths emerging from Bt cornfields could slow or reverse resistance development. It is important that the released moths remain in or near the release site long enough to mate. A previous study showed that moths emerging from the pupal stage do not stay near the field in which they are released. In this study we tried releasing marked moths of different ages and different mating status to determine if there is a category of lab-reared moths that can be released and relied upon to stay near the release site. However, almost all of the marked moths dispersed away from their release site on the first night regardless of age or mating status. The results indicate that the strategy of mass-releasing susceptible European corn borer moths to help slow the development of resistance to Bt-corn may not be possible. This study will help guide entomologists attempting to develop strategies to slow the development of resistance by European corn borer to Bt corn.

Technical Abstract: The European corn borer, Ostrinia nubilalis (Hubner), is often controlled with genetically modified corn hybrids [Bacillus thuringiensis (Bt) corn] in the U.S. If Bt-resistant moths are detected in the field, mitigation-remediation tactics must be implemented to sustain the efficacy of insecticidal, transgenic corn. Mass releasing laboratory-reared, susceptible moths near aggregation sites to mate with locally emerging resistant moths is a possible remediation tactic, but it is imperative that the former remain in or near the release site long enough to mate. Understanding adult dispersal behavior relative to the timing of mating is important because it directly affects patterns of gene flow and the rate at which Bt resistance moves through a population. Previous work shows that newly-eclosed moths do not remain in close proximity to their natal field. However, moth age, reproductive development, or mating status may influence the propensity to disperse. The objectives of this study were to determine the effect of adult age (0-3, 4-6, and 7-10 days old) and mating status on dispersal of moths released in small-grain aggregation plots. Less than 1% of the marked moths released in the aggregation plots remained more than 1 night. More males than females were recovered. Moth age influenced dispersal, with mostly 4-6 day old moths being recovered. Conversely, mating status did not affect the number of moths recovered. Given the paucity of marked moths recovered near their release sites, mass releases of adults may not be a viable tactic to combat the spread of resistance to Bt-corn.