Critical facets of European corn borer adult movement ecology relevant to mitigating field resistance to Bt-corn

Authors: Sappington, Thomas

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/23/2024
Publication Date: 2/27/2024
Citation: Sappington, T.W. 2024. Critical facets of European corn borer adult movement ecology relevant to mitigating field resistance to Bt-corn. Insects. https://doi.org/10.3390/insects15030160.
DOI: https://doi.org/10.3390/insects15030160

Interpretive Summary: The European corn borer (Ostrinia nubilalis, Hübner) is a major pest of corn, managed successfully in North America since 1995 with transgenic Bt-corn. However, practical field resistance and early-warning increases in frequency of resistance genes for all available insecticidal Bt proteins expressed in corn were detected recently at several locations in Canada. Given the high mobility of adult moths, rapid geographic spread of resistance is a serious threat to both Canadian and U.S. agriculture, unless containment and mitigation measures are designed and implemented quickly. Effective strategies must account for gene flow consistent with new understandings of this species' complex movement ecology, which includes, surprisingly, migration. This information will be useful to academic, industry, and government scientists, modelers, and regulators in developing and implementing effective resistance management tactics and strategies.

Technical Abstract: The European corn borer (Ostrinia nubilalis, Hübner) is a major lepidopteran pest of corn, which has been managed successfully in North America since 1995 with transgenic Bt-corn. However, practical field resistance to corn expressing the Cry1Fa insecticidal Bt protein was detected in Nova Scotia, Canada, in 2018, and significant decreases in susceptibility to this and the other three available protein toxins Cry1Ab, Cry1A.105, and Cry2Ab were reported recently from several additional locations in Canada. Cry1Fa resistance appears to be spreading geographically from its origin, and evidence suggests independent evolution of resistance is occurring in scattered hotspots to all four toxins. Given the high mobility of adult European corn borer, rapid geographic spread of resistance is expected unless containment and mitigation measures are designed and implemented quickly. Evolution and spread of resistance are functions of gene flow, which in turn is a function of dispersal, so design of effective resistance management plans, including mitigation tactics and strategies, must take the insect's movement into account. Recent advances in characterizing European corn borer movement ecology have revealed a number of surprises, chief among them that a large percentage of adults disperse from the natal field via true migratory behavior, most before mating. This undermines a number of common key assumptions about adult behavior, patterns of movement, and gene flow, and stresses the need to reassess how ecological data are interpreted and how movement in models should be parameterized. While many questions remain concerning adult European corn borer movement ecology, the information currently available is coherent enough to construct a generalized framework useful for designing successful Bt-resistance prevention, remediation, and mitigation strategies.