Molecular genetic markers among and within populations of the European corn borer (Lepidoptera: Pyralidae) and screwworms (Diptera: Caliphoridae)

Ostrinia nubilalis (Hübner), has 3 morphologically indistinguishable voltinism ecotypes. Random Amplified Polymorphic DNA - Polymerase Chain Reaction (RAPD-PCR) was used to discriminate ecotypes of the ECB. Genomic DNA samples from the ECB were screened with 120 random primers. Ten of these primers yielded 21 clear and reproducible RAPD markers. Dendrograms showed the multivoltine ecotype to be genetically separated from univoltine and bivoltine ecotypes. These results provided evidence of genetic variation at the molecular level among ECB ecotypes. The RAPD-PCR technique proved to be a powerful tool for identifying intraspecific variation in the ECB. 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, C. macellaria (F.). Interspecific variation between primary screwworm and secondary screwworm was revealed by PCR based Restriction Fragment Length Polymorphism (PCR-RFLP) analysis of mitochondrial DNA. Twelve primers, covering about 65% of the screwworm mitochondrial genome, were studied. After screening 30 restriction enzymes, 29 discriminating PCR-RFLP patterns were obtained by digesting 8 of the PCR products with 16 restriction enzymes. This method proved to be a useful tool for screwworm species identification. The RAPD-PCR technique was used to develop markers for the two screwworm species. Of 120 arbitrary primers screened, 21 primers produced a number of distinct markers that differentiated primary screwworm from secondary screwworm. Then, eight of the 21 primers (with clear and reproducible markers) were tested with 4 populations of each species; 12 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 be used to investigate intraspecific variation. The RAPD method can be somewhat more sensitive than RFLP analysis, which focuses on only one or a few specific DNA segments