Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/19/2008
Publication Date: 4/1/2009
Citation: Kim, K.S., Szendrei, Z., Rodriguez-Saona, C., Mulder, P.G., Sappington, T.W. 2009. Molecular Diagnostic for Boll Weevil (Coleoptera: Curculionidae) Based on Amplification of Three Species-specific Microsatellites. Journal of Economic Entomology. 102(2):759-766. 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 because boll weevils can fly long distances, areas from which they have been eradicated are monitored closely with traps. When boll weevils are detected in a trap, very expensive procedures are implemented to ensure that they do not reinfest the area. Therefore, it is very important to be sure that a weevil in a trap is truly a boll weevil and not a similar weevil that may accidently get in the trap. A few weevils look similar, and the chances of a misidentification are compounded when ants or beetles get into the trap and feed on captured weevils, leaving behind only body parts. We have developed a molecular method to identify boll weevils based on a simple DNA fingerprint. We show that the pattern of DNA produced is specific to boll weevils and not to other common weevils that might get into the traps. We also show that the molecular technique can identify boll weevils from legs, wings, and other body parts, so that it is sensitive enough to use even if a trapped weevil is broken-up in the trap. 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 the United States.
Technical Abstract: The boll weevil, Anthonomus grandis Boheman (Coleoptera: Curculionidae), is a serious pest of cultivated cotton in the Americas, and reinfestation of zones from which they have been eradicated is of perpetual concern. Extensive arrays of pheromone traps monitor for reintroductions, but occasionally the traps collect non-target weevils that can be misidentified by scouts. For example, the congeneric pepper weevil, A. eugenii Cano, is attracted to the boll weevil pheromone lure, and other superficially similar weevils may blunder into the trap. Though morphologically distinguishable by trained personnel, the potential for misidentification is compounded when captured weevils are dismembered or partially consumed by ants or carabids that sometimes feed on them in the traps. Because both false positives due to misidentification and false negatives caused by compromised morphological features of trapped insects can have very expensive consequences, a molecular diagnostic tool would be of great value to eradication managers. We demonstrate that a cocktail of three genomic primer pairs in a single polymerase chain reaction (PCR) amplify three species-specific microsatellites that unambiguously distinguish A. grandis from three other weevil species tested, including A. eugenii, the cranberry weevil A. musculus Say, and the pecan weevil Curculio caryae Horn. A universal ITS primer pair included in the cocktail cross-amplifies DNA from all four species. Furthermore, the diagnostic primers amplified the target microsatellites from various A. grandis adult body parts, indicating that the PCR technology using the primer cocktail is sensitive enough to identify A. grandis even when the body is broken-up in a trap.