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Title: Distribution and persistence of sterile screwworms (Diptera: Calliphoridae) released at the Panama-Colombia border

Author
item Skoda, Steven
item Phillips, Pamela
item SAGEL, AGUSTIN - Us Embassy, Panama
item Chaudhury, Muhammad

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/8/2016
Publication Date: 4/1/2017
Citation: Skoda, S.R., Phillips, P.L., Sagel, A., Chaudhury, M.F. 2017. Distribution and persistence of sterile screwworms (Diptera: Calliphoridae) released at the Panama-Colombia border. Journal of Economic Entomology. 110(2):783-789.

Interpretive Summary: Eradication of the screwworm from the United States, Mexico and Central America using the sterile insect technique was a resounding success. Each year livestock producers reap significant benefits when they do not need to treat animal wounds for this hideous affliction. The savings to wildlife, pets and reduced human suffering are immeasurable. Guarding against the reintroduction of screwworms to North America or introduction to any other screwworm free area relies on continued successful maintenance of a barrier at the Panama to Colombia border. We studied the distribution and persistence of mass reared, radiation sterilized screwworms that are released in the barrier. First we determined that the fluorescent dust used to mark the flies was not detrimental to them – it wasn’t. We then compared the distribution of two strains (Panama-95 and Jamaica-06) of sterile, mass reared screwworms released in the barrier. There was no difference. Lastly we determined the distribution and persistence of sterile, mass reared Jamaica-6 screwworms collected from two different adult emergence systems and marked with fluorescent dusts. There was no difference between the two collection systems, flies distributed homogeneously and persisted for >6 days. This information was useful in implementing use of a new sterile fly emergence/collection system, a new strain for the barrier maintenance program, and will be valuable for evaluating alternative release strategies of sterile screwworms by the eradication and barrier maintenance program.

Technical Abstract: The sterile insect technique is currently used by the Comisión Panamá - Estados Unidos para la Erradicación y Prevención del Gusano Barrenador del Ganado (COPEG) to maintain a barrier at the border between Panama and Colombia that prevents screwworms, Cochliomyia hominivorax (Coquerel), from South America reinfesting North America. Before studying the distribution and persistence of sterilized, mass produced screwworms that have been released in the barrier zone the application of fluorescent dust (~1.0 mg/fly) to pupae and to newly emerged adults was evaluated to determine the effect on fly survival. The flight ability of flies collected from two adult emergence/collection systems (enclosed towers and open chambers) and treated with low (~0.20 mg/fly) or high (~1.0 mg/fly) amounts of fluorescent powder was then compared. The distribution and persistence of sterile screwworms marked with fluorescent powder (~0.20 mg/fly), after collection from the same two adult emergence/collection systems, was compared after their release in the barrier zone. Results showed: 1) fluorescent dust had no negative impact on sterile screwworm longevity or flight ability; 2) no differences were detected with sterile flies collected from the two emergence systems; and 3) sterile screwworms distributed evenly in the barrier zone and persisted for > 6 d. This information was useful in implementing use of a new sterile fly emergence/collection system, a new strain by COPEG for the barrier maintenance program, and will be valuable for evaluating alternative release strategies of sterile screwworms by the eradication and barrier maintenance program.