|Norman, jr., John|
Submitted to: Journal of Economic Entomology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/3/2005
Publication Date: 2/1/2006
Citation: Sappington, T.W., Arnold, M.D., Brashears, A.D., Parajulee, M.N., Carroll, S.C., Knutson, A.E., Norman, Jr., J.W. 2006. Dispersal of boll weevils (Coleoptera: Curculionidae) from cotton modules before ginning. Journal of Economic Entomology. 99:67-75. Interpretive Summary: The boll weevil is a major pest of cotton, and great efforts are underway to eradicate it from the U.S. There is concern that weevils may fly from the surface of modules of cotton harvested in areas that are still heavily infested during or after transport to cotton gins in neighboring eradication zones. We found that boll weevils disperse rapidly from the surface of the module, as long as it is warm enough to fly, and as long as they are not trapped under the tarp that farmers use to cover the top of modules. All weevils trapped under the tarp on very hot days were dead by 24 hours, and most (but not all) died in very cold weather. The biggest threat of reintroduction of boll weevils to eradication zones will occur when an infested module is harvested and transported in cold weather followed by warm weather at the gin yard while the module awaits its turn to be processed, or when it is immediately transported on days of mild temperatures. These findings will be used by state departments of agriculture and regulatory agencies to design appropriate measures minimizing the risk of boll weevil reintroductions during and after module transport.
Technical Abstract: We conducted experiments to characterize boll weevil dispersal from the surfaces of cotton modules during and after transport to the gin yard. Mark-release-recapture experiments indicated that most weevils disperse rapidly from the module surface, temperature permitting, unless confined under a module tarp. Most marked weevils died under the tarp when temperatures were high, but some were unaccounted for and may have escaped lethal temperatures by burrowing into the loose cotton on top of the module. Nevertheless, a low percentage of live weevils were recovered after 24 h on both the side and the top surfaces of modules, representing potential dispersants. Mortality of boll weevils caged on the top surface of a module was very high after 1-4 d when maximum air temperatures were > 31 degrees C, or when minimum temperatures were < 7 degrees C, but a few survived even after experiencing a minimum daily temperature of -12 degrees C. Under hot and cold weather conditions, survival was higher under the tarp than on the open surface of the module, but mortality was 100% in both locations on very hot days. Our results indicate that although the threat to an eradication zone posed by boll weevil dispersal from an infested module is quite low under most environmental conditions, it is likely greatest when: 1) the module is constructed and transported at temperatures too cool for weevil flight, followed by a change to warm sunny conditions at the gin yard, which would promote dispersal as the module awaits processing; or 2) when such a module is immediately transported during mild weather.