Molecular Genetic and Hybridization Studies ofDiorhabdaspp. Released for Biological Control ofTamarix

Abstract

AbstractThe genusDiorhabda(Coleoptera: Chrysomelidae) was recently revised, using morphological characters, into five tamarisk-feeding species, four of which have been used in the tamarisk (Tamarixspp.) biological control program in North America and are the subject of these studies. The taxonomic revision is here supported using molecular genetic and hybridization studies. FourDiorhabdaspecies separated into five clades using cytochrome c oxidase subunit 1 sequence data withDiorhabda elongataseparating into two clades. Amplified fragment length polymorphism (AFLP) analysis using genomic DNA revealed only four clades, which corresponded to the four morphospecies. Hybridization between the four species yielded viable eggs in F1crosses but viability was significantly lower than achieved with intraspecific crosses. Crosses involvingDiorhabda carinulataand the other three species resulted in low F2egg viability, whereas crosses betweenD. elongata, Diorhabda sublineataandDiorhabda carinataresulted in > 40% F2egg viability. Crosses betweenD. carinulataand the other three species resulted in high mortality ofD. carinulatafemales due to genital mismatch. AFLP patterns combined with principal coordinates analysis enabled effective separation betweenD. elongataandD. sublineata, providing a method to measure genetic introgression in the field.