P. Litjens et al., Characterization of the screwworm flies Cochliomyia hominivorax and Cochliomyia macellaria by PCR-RFLP of mitochondrial DNA, MED VET ENT, 15(2), 2001, pp. 183-188
The primary screwworm fly Cochliomyia hominivorax (Coquerel) (Diptera: Call
iphoridae) is one of the most important insect pests of livestock in neotro
pical regions, whereas Cochliomyia macellaria (Fabricius) (Diptera: Calliph
oridae), the secondary screwworm, is of medical and sanitary importance bec
ause of its role in the dissemination of pathogens. These two species share
morphological similarities and both may occur in the same myiasis, but in
different developmental stages. In this work, the usefulness of PCR-RFLP (p
olymerase chain reaction-restriction fragment length polymorphism) of mitoc
hondrial DNA (mtDNA) for the unambiguous identification of C. hominivorax a
nd C. macellaria was investigated. Two specific regions of mtDNA were ampli
fied: 870bp from Cytochrome oxidase subunit I and 2100bp from the A+T rich/
12S region from C. hominivorax and C. macellaria specimens from different a
reas of Brazil. Reliable species-specific PCR-RFLP results were obtained fo
r the CO I region and the A+T rich/12S region using the restriction enzymes
Dra I and Ssp I. These results confirm the conservation of CO I diagnostic
restriction sites previously reported and demonstrate the usefulness of th
e control region sequences as an efficient marker for PCR-RFLP identificati
on of Brazilian screwworm flies. The occurrences of intraspecific polymorph
ic patterns are discussed based on frequencies and potential conflicts for
species identification. PCR-RFLP provides a potentially useful method for i
dentifying samples from the areas where these species are monitored.