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Title: Genetic studies of Gonatocerus metanotalis populations from Argentina uncover divergent clades: A prospective egg parasitoid candidate agent for the glassy-winged sharpshooter in California.

Author
item De Leon, Jesus
item LOGARZO, GUILLERMO - USDA,ARS,SABCL,ARGENTINA
item TRIAPITSYN, SERGUEI - UC-RIVERSIDE, CA

Submitted to: CDFA Pierce's Disease Control Program Research Symposium
Publication Type: Proceedings
Publication Acceptance Date: 9/25/2006
Publication Date: 11/27/2006
Citation: De Leon, J.H., Logarzo, G.A., Triapitsyn, S.V. 2006. Genetic studies of Gonatocerus metanotalis populations from Argentina uncover divergent clades: A 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. 52.

Interpretive Summary: In the present study, two molecular methods were utilized to genetically characterize a prospective natural enemy candidate agent (Gonatocerus metanotalis) from Argentina, South America for a neoclassical biological control program in California against the invasive glassy-winged sharpshooter (GWSS), Homalodisca vitripennis (=H. coagulata). DNA fingerprinting of six geographic populations uncovered several banding patterns, giving the first clue of genetic differences among the populations. A phylogenetic analysis inferred by the mitochondrial cytochrome oxidase subunit I (COI) gene uncovered three distinct clades with strong bootstrap or statistical support. With the exception of one population (Campo Grande), all populations fell into one of three clades. Individuals from Campo Grande fell into the three clades, suggesting that three strain or species are present in this location. To lend support to the species groups considered, a phylogenetic analysis was performed along with 16 other Gonatocerus species. Species boundaries were confirmed and again three well-supported clades were uncovered in G. metanotalis. The molecular data is suggestive of a species level divergence. Understanding possible cryptic variation in this prospective GWSS egg parasitoid candidate agent is critical to the biological control program in California.

Technical Abstract: Two molecular methods were utilized to genetically distinguish geographic populations of Gonatocerus metanotalis (Ogloblin) (Hymenoptera: Mymaridae) from Argentina and to begin to test the possibility that this South American species could exist as a cryptic species complex. Gonatocerus metanotalis is a prospective egg parasitoid candidate agent for a neoclassical biological control program in California against the invasive glassy-winged sharpshooter (GWSS), Homalodisca vitripennis (Germar) [=H. coagulata (Say)]. Six populations were analyzed: Campo Grande (Misiones Province), Tartagal (Salta), Tafi Viejo (Tucuman), near PROIMI (Tucuman), Santa Clara (Jujuy), Clorinda (Formosa). As a first approach, inter-simple sequence repeat-polymerase chain reaction (ISSR-PCR) DNA fingerprinting was performed with a 5'-anchored ISSR primer. Several distinct banding patterns were identified among the populations with some band sharing and in certain populations (Tartagal and Santa Clara) there was extensive variation. Next, a phylogenetic analysis inferred by the mitochondrial cytochrome oxidase subunit I (COI) gene was performed. A neighbor-joining distance tree clustered the G. metanotalis populations into three main distinct clades supported by very strong bootstrap values (100%). With the exception of one population (Campo Grande), all individuals from the populations fell into one of the three clades. Individuals from Campo Grande clustered into the three clades, suggesting that three sympatic strains may be present in this location. A phylogenetic analysis performed by the neighbor-joining algorithmic method along with 16 other named and two unnamed Gonatocerus Nees species confirmed species boundaries and again uncovered three main distinct clades in G. metanotalis. Very strong bootstrap support (100%) was seen for both the G. metanotalis clades and for all of the Gonatocerus species. Understanding possible cryptic variation in this prospective GWSS egg parasitoid candidate agent is critical to the biological control program in California.