GENETIC-VARIATION IN PERFORMANCE TRAITS AND THE POTENTIAL FOR HOST SHIFTS IN ENCHENOPA TREEHOPPERS (HOMOPTERA, MEMBRACIDAE)

Host plant shifts by phytophagous insects are often hypothesized as me ans through which new species could genetically differentiate. For gen etic divergence to occur between populations on original and novel hos ts, the colonizing population must possess genetic variation in perfor mance traits allowing use of and selection by the new host. To test fo r the existence of genetic variation in Enchenopa treehoppers for the use of novel host plants in the genus Viburnum, we performed a 4-way f ull sib analysis. Related insects were exposed to 4 different plant sp ecies in greenhouse and field settings: the original host plant and 3 novel host species. We estimated genetic variation in performance trai ts of male and female longevity, and female fecundity and calculated f itness values, nymphal survival, and male and female developmental tim e to adult eclosion. We found significant genetic variation in traits influencing both survival and reproduction. There were significant int eractions between genotype and host, indicating some genotypes are mor e adept than others at using new hosts. We conclude that sufficient ge netic variation exists in this population to facilitate successful shi fts to these new hosts.