|De Leon, Jesus|
Submitted to: CDFA Pierce's Disease Control Program Research Symposium
Publication Type: Proceedings
Publication Acceptance Date: 9/25/2006
Publication Date: 11/25/2006
Citation: De Leon, J.H., Logarzo, G.A., Triapitsyn, S.V. 2006. Genetic characterization of Gonatocerus tuberculifemur from South America uncovers divergent clades: prospective egg parasitoid candidate agent for the glassy-winged sharpshooter in California. CDFA Pierce's Disease Control Program Research Symposium, November 27-29, 2006, San Diego, California. p. 40. Interpretive Summary: In the present study, we genetically characterized a prospective natural enemy candidate agent (Gonatocerus tuberculifemur) for a neoclassical biological control program against the invasive glassy-winged sharpshooter (GWSS) (Homalodisca vitripennis) (=H. coagulata) in California. Identifying the correct natural enemy is crucial for a successful biological control program. Two molecular methods were used to characterize five geographic populations from South America (Argentina and Chile). Inter-simple sequence repeat-polymerase chain reaction (ISSR-PCR) DNA fingerprinting uncovered fixed geographic variation in a population from San Rafael, Mendoza Province, Argentina. A phylogenetic analysis inferred by the cytochrome oxidase subunit I gene (COI) uncovered two distinct clades with very strong bootstrap support, with all individuals from the San Rafael population clustering into their own unique clade. The two molecular methods were in accord and the evidence is suggestive of a species level divergence. Since G. tuberculifemur is under consideration as a potential biological control agent for the invasive GWSS in California, understanding possible cryptic variation of this species is critical.
Technical Abstract: We genetically characterized the prospective South American egg parasitoid candidate agent, Gonatocerus tuberculifemur, of the glassy-winged sharsphooter (GWSS), Homalodisca vitripennis (Germar) [=H. coagulata (Say)] for a neoclassical biological control program in California. Two molecular methods, inter-simple sequence repeat-polymerase chain reaction (ISSR-PCR) DNA fingerprinting and a phylogenetic approach inferred by the mitochondrial cytochrome oxidase subunit I gene (COI). Five geographic populations from South America were analyzed; in addition, a phylogenetic analysis was performed with several named and two unnamed Gonatocerus species. DNA fingerprinting uncovered a fixed geographic banding pattern difference in the population from San Rafael, Mendoza Province, Argentina. The COI analysis uncovered haplotype or geographic structure in G. tuberculifemur. A neighbor-joining distance tree clustered the populations into two well-supported distinct clades with very strong bootstrap values (96-100%) with the population from San Rafael clustering into a separate clade than the rest of the South American populations. No haplotype sharing was observed between individuals from the two clades. A phylogenetic analysis performed by the neighbor-joining method of 15 Gonatocerus species confirmed species boundaries and again uncovered two distinct clades in G. tuberculifemur with very strong bootstrap support (96-100%). The two molecular methods were in accord and the evidence is suggestive of a species level divergence. Because G. tuberculifemur is under consideration as a potential biological control agent for the invasive GWSS in California, understanding possible cryptic variation of this species is critical.