Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/11/2004
Publication Date: 10/1/2004
Citation: Sappington, T.W., Brashears, A.D., Parajulee, M.N., Carroll, S.C., Arnold, M.D., Baker, Jr., R.V. 2004. Boll weevil (Coleoptera: Curculionidae) survival through cotton gin trash fans. Journal of Economic Entomology. 97:1612-1618. 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 if gins in eradicated or weevil-suppressed areas process harvested cotton from neighboring infested areas, weevils may escape to reinfest the eradication zone. Previous studies showed that the most likely way for a weevil to escape once it enters the gin plant is in the gin trash that is separated from the seed cotton by cleaning machinery. Gin trash is passed through a high speed fan that pulverizes the trash. We showed that free adult boll weevils cannot survive passage through a trash fan tested at any speed. However, a few weevils can survive passage through a fan, even when operated at high speeds, if they are inside a green boll. We found that increasing fan speed will not solve this problem. Our results indicate that if a device can be developed to partially crack open or crush bolls before they get to the trash fan, weevil survival may be reduced to the point where escape through this route is no longer a concern. This study provides regulatory and action agencies with information necessary to assess the risk of boll weevil reintroduction to eradication zones through ginning of infested seed cotton, and to design appropriate guidelines to manage that risk.
Technical Abstract: There is concern that cotton gins may serve as loci for reintroduction of boll weevils (Anthonomus grandis Boheman) to eradicated or suppressed zones when processing infested cotton from neighboring zones. Previous work has shown that virtually all weevils entering the gin in the seed cotton will be removed before they reach the gin stand. Those not killed by the seed cotton cleaning machinery will be shunted alive into the trash fraction, which passes through a centrifugal trash fan before exiting the gin. The objective of this study was to determine survival potential of boll weevils passed through a trash fan. Marked adult weevils were distributed in gin trash and fed through a 107-cm (42-in) diameter centrifugal fan operated across a range of fan-tip speeds. A small number of weevils were recovered alive immediately after passage through the fan, but all were severely damaged and did not survive 24 h. In another experiment, bolls infested with weevils were fed through the fan. Several teneral adults survived 24 h, and there was no evidence that fan-tip speed affected either initial survival of weevils, or the number of unbroken boll locks that could harbor an infesting weevil. Thus, designating a minimum fan-tip speed for ensuring complete kill is not possible for the boll weevil. Experiments suggest that a device installed in a gin that partially crushes or cracks bolls open before entering a trash fan will increase weevil mortality, possibly enough that further precautions would be unnecessary.