Suitability of Random Amplified Polymorphic DNA for Genetic Markers in the Aphid Parasitoid, Aphelinus asychis Walker

The repeatability, variability, transmission, and linkage relationships of random amplified polymerphic DNA (RAPD) fragments were examined using six inbred lines of the haplodiploid parasitoid, Aphelinus asychis, originally collected on one date from a single held in southern France. Repeatability of RAPD fragments could be adequately judged using two replicate amplifications of the same individual in the same amplification run. Thirty-one of 136 repeatable fragments generated by 14 primers were polymorphic among lines. Segregation ratios in Fz males did not differ from 1:1 and extrachromosomal transmission was not observed. However, 5 nonparental bands that would increase the apparent number of loci by 16.2% in outbreeding populations were detected in hybrid F1 females. In addition, linkage analysis indicates that the 31 polymorphic bands represent 19 presence-absence loci and 6 biallelic, fragment length polymorphism (FLP) or FLP-like loci. Four linkage groups were detected. Our main conclusion is that RAPD polymerphisms cannot be used as genetic markers unless information identifying nonparental bands and FLP and FLP-like loci is obtained. This information can be obtained during the course of typical population surveys in haplodiploid species because of male haploidy. In diploid species though, crossing experiments or DNA hybridization tests to establish homology are necessary prior to working with unpedigreed populations.