Use of RAPD analyses to estimate population genetic parameters in the alfalfa leaf-cutting bee, Megachile rotundata

RAPD analyses were performed on five geographically isolated populations of Megachile rotundata. We used haploid males of the alfalfa leaf-cutting bee, M. rotundata, to overcome the limitation of the dominance of RAPD markers in the determination of population genetic parameters. Sixteen primers gave rise to 130 polymorphic and 31 monomorphic bands. The unbiased estimators calculated in this study include within- and between-population heterozygosity, nucleotide divergence, and genetic distance. The genetic diversity (H = 0.32-0.35) was found to be about 10 times that of previous estimates (H = 0.033) based on allozyme data. Contrary to the data obtained at the protein level, our results suggest that Hymenoptera do not have a lower level of genetic variability at the DNA level compared with other insect species. Regardless of the different assumptions underlying the calculation of heterozygosity, divergence, and genetic distance, all five populations showed a parallel interrelationship for the three parameters. We conclude that RAPD markers are a convenient tool to estimate population genetic variation in haploid M. rotundata and that with an adequate sample size the technique is applicable to the evaluation of divergence in diploid populations. Key words : Megachile rotundata, RAPD, heterozygosity, genetic distance, nucleotide divergence.