Molecular Genetic and Hybridization Studies of<i>Diorhabda</i>spp. Released for Biological Control of<i>Tamarix</i>

Abstract

Abstract The genus Diorhabda (Coleoptera: Chrysomelidae) was recently revised, using morphological characters, into five tamarisk-feeding species, four of which have been used in the tamarisk ( Tamarix spp.) 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. Four Diorhabda species separated into five clades using cytochrome c oxidase subunit 1 sequence data with Diorhabda elongata separating 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 F 1 crosses but viability was significantly lower than achieved with intraspecific crosses. Crosses involving Diorhabda carinulata and the other three species resulted in low F 2 egg viability, whereas crosses between D. elongata, Diorhabda sublineata and Diorhabda carinata resulted in &gt; 40% F 2 egg viability. Crosses between D. carinulata and the other three species resulted in high mortality of D. carinulata females due to genital mismatch. AFLP patterns combined with principal coordinates analysis enabled effective separation between D. elongata and D. sublineata , providing a method to measure genetic introgression in the field.