ISSR-PCR DNA FINGERPRINTING UNCOVERS DISTINCT BANDING PATTERNS IN GONATOCERUS SPECIES 3 (G. sp. 3) INDIVIDUALS EMERGING FROM DIFFERENT HOST TRIBES: A PROSPECTIVE EGG PARASITOID CANDIDATE AGENT FOR THE GLASSY-WINGED SHARPSHOOTER IN CALIFORNIA

• Author(s): de Le?n, Jesse; Logarzo, Guillermo; Triapitsyn, Serguei; Morgan, David;
• Abstract: We started work to genetically characterize a prospective glassy-winged sharsphooter (GWSS), Homalodisca vitripennis (Germar) [=H. coagulata (Say)] egg parasitoid biological control candidate agent from South America known as Gonatocerus species 3 (G. sp. 3). This species is morphologically very similar to G. tuberculifemur, another prospective agent from South America. We asked two questions, 1) are G. sp. 3 and G. tuberculifemur the same species and 2) are two collections of G. sp. 3 individuals emerging from different host tribes (Proconiini and Cicadellini) genetically distinct. Or, in both cases, are we seeing genetic variation of the same species. Two molecular methods were utilized to begin to study these species, the very sensitive inter-simple sequence repeat-polymerase chain reaction (ISSR-PCR) DNA fingerprinting and mitochondrial cytochrome oxidase subunit I gene (COI) variation. ISSR-PCR analysis performed together on both G. sp. 3 and G. tuberculifemur uncovered the following: 1) as previously shown, G. tuberculifemur geographic populations were genetically distinct, 2) G. sp. 3 and G. tuberculifemur were very clearly distinct, and 3) banding patterns differences (about four bands) distinguished the two collections of G. sp. 3. A single most parsimonious tree clustered the current specimens in the following fashion: 1) as previously shown, the geographic populations of G. tuberculifemur clustered into two well-supported distinct clades with very strong bootstrap values (90-99%), and 2) the G. sp 3 collections clustered along with clade 2 (San Rafael population) of the G. tuberculifemur populations, though one G. sp. 3 collection (Jan 05; Proconiini host) forms a unique clade with moderate bootstrap support (63%). Even though, the divergence between the two G. sp. 3 collections was very small, the two shared no haplotypes. The current results confirm that ISSR-PCR DNA fingerprinting using a 5-anchored ISSR primer is an excellent molecular diagnostic tool for distinguishing G. sp. 3 from both clades of G. tuberculifemur. COI sequence variation effectively distinguished G. sp. 3 from G. tuberculifemur individuals from clade 1, though it did not effectively separate G. sp. 3 from G. tuberculifemur individuals from clade 2 (San Rafael population). We conclude that based on ISSR-PCR analysis, G. sp. 3 and G. tuberculifemur and both collections of G. sp. 3 are clearly genetically distinct. The only way to confirm whether these specimens are actually cryptic or different species is by performing hybridization studies. These molecular results are important to the biological control program in California.
• Publication Date: Nov 2006
• Journal: 2006 Pierce's Disease Research Symposium