ECOLOGICALLY-BASED MANAGEMENT OF INSECT PESTS OF CORN
Location: Corn Insects and Crop Genetics Research
Title: Multidisciplinary Fingerprints: Forensic Reconstruction of an Insect Reinvasion
Submitted to: Journal of the Royal Society Interface
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 14, 2009
Publication Date: April 6, 2010
Citation: Kim, K.S., Jones, G.D., Westbrook, J.K., Sappington, T.W. 2010. Multidisciplinary Fingerprints: Forensic Reconstruction of an Insect Reinvasion. Journal of the Royal Society Interface. 7(45):677-686.
Interpretive Summary: Boll weevils are a serious pest of cotton in the south-central U.S. They have been eradicated from much of the Cotton Belt, but the eradication is ongoing in some areas, especially southern and eastern Texas. Because boll weevils can fly long distances, potential reinvasion of weevil-free areas is monitored closely with traps. In August 2007, large numbers of boll weevils were captured unexpectedly in the Southern Rolling Plains (SRP) eradication zone of West-Central Texas after the passage of Tropical Storm Erin. The SRP had been free of weevils since 2003. We used a combination of DNA fingerprinting, pollen fingerprinting, and wind analysis to determine where the immigrant weevils came from. Alone, these methods can provide clues to a migratory insect's origin, but together they are a powerful way to determine the source. The results strongly implicate the region around Uvalde, TX, located to the south of the SRP, as the probable source of the immigrant boll weevils. This information will be of use to eradication officials and scientists at the USDA-Animal and Plant Health Inspection Service, the Texas Department of Agriculture, and the Texas Boll Weevil Eradication Foundation as they strive to finally eliminate this pest from Texas. It also serves as a model for determining origins of other quarantined or invasive pests that will be of use to regulatory agencies and scientists studying such highly mobile insects.
Beginning late August 2007, more than 150 boll weevils, Anthonomus grandis, were unexpectedly captured across an extensive area of the Southern Rolling Plains (SRP) eradication zone of West-Central Texas, which was essentially weevil-free since 2003. This outbreak was detected soon after the passage of Tropical Storm Erin through the Winter Garden district of the South Texas/Winter Garden eradication zone on the night of 16 August. The synchrony and broad geographic distribution of captured weevils around the southeastern perimeter of the SRP suggest that long-distance dispersal was responsible for the reinvasion. We integrated three types of assessment to reconstruct the geographic origin of the immigrants: 1) DNA fingerprinting, 2) pollen fingerprinting, and 3) atmospheric trajectory analysis. We hypothesized the boll weevils originated in the western Southern Blacklands (SBL) zone near Cameron, or in the Winter Garden district near Uvalde, the nearest regions with substantial populations. Genetic tests broadly agree that the immigrants originated south or southeast of the SRP zone, probably in regions represented by Uvalde or Weslaco. Although the Uvalde pollen profile did not match that of the SRP weevils perfectly, it was a much better fit than the Cameron profile. Wind trajectories supported daily wind-aided dispersal of weevils from the Uvalde region to the SRP from 16-24 August, but failed to support migration from the Cameron region. Taken together the forensic evidence strongly implicates the Winter Garden district near Uvalde as the source. Such a multidisciplinary approach is widely applicable to other invasive and quarantine insects, and makes inferences about origins more robust than is otherwise possible.