Submitted to: Bulletin of Entomological Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/19/2001
Publication Date: 2/1/2002
Citation: Skoda, S.R., Pornkulwat, S., Foster, J.E. 2002. Random amplified polymorphic DNA markers for discriminating Cochliomyia hominivorax from C. macellaria (Diptera: Calliphoridae). Bulletin of Entomological Research. 92: 89-96. Interpretive Summary: The primary screwworm was once the most important pest of livestock in the United States. A successful eradication program against the primary screwworm has eliminated it from the U.S., and to help ensure against reintroductions, is pushing the buffer zone through Central America. Part of the success of the eradication program relies on quick and accurate identification of all life stages, including the very small early life stages, which are easily confused with other flies. Identification is particularly important if there is a suspected outbreak of primary screwworm in an area that was considered eradicated, or even worse, in an area that never before had primary screwworms. We used a molecular genetic technique, known as random amplified polymorphic DNA - polymerase chain reaction (RAPD-PCR), to differentiate the primary screwworm from the secondary screwworm (the species most commonly misidentified in the early life stages). RAPD-PCR successfully differentiated the two fly species, is quick (can be completed in 2 days), and is cost effective. We also found that RAPD-PCR should be suitable for determining the general geographic origin of the samples, but further molecular genetic studies are needed: if true, this will help action agencies (such as the USDA Animal and Plant Health Inspection Service) in correcting problems at the source if accidental introductions occur.
Technical Abstract: Primary screwworm, Cochliomyia hominivorax (Coquerel), is one of the most important pests of livestock in the Western Hemisphere. During early immature stages, it is morphologically similar to the secondary screwworm, Cochliomyia macellaria (F.). to develop markers for each species, the random amplified polymorphic DNA - polymerase chain reaction (RAPD-PCR) technique was used. Of one hundred twenty arbitrary primers screened, twenty-one arbitrary primers produced a number of distinct markers potentially useful in differentiating primary screwworm from secondary screwworm. Then, eight of the twenty-one primers that produced clear and reproducible markers were tested with 4 populations of each species; twelve RAPD markers were found. The RAPD technique proved to be useful in discriminating primary screwworm from secondary screwworm; and because some primers showed intraspecific markers, the technique may also be used to investigate population variation.