|De Leon, Jesus|
Submitted to: CDFA Pierce's Disease Control Program Research Symposium
Publication Type: Proceedings
Publication Acceptance Date: 11/7/2005
Publication Date: 12/1/2005
Citation: De Leon, J.H., Hagler, J.R., Logarzo, G., Morgan, D.J. 2005. The utility of inter-simple sequence repeat-polymerase chain reaction (ISSR-PCR) to distinguish geographic populations of the smoke-tree sharpshooter Homalodisca liturata and egg parasitoid species of the genus Gonatocerus. Proceedings of CDFA Pierce's Disease Control Program Research Symposium, December 5-7, 2005, San Diego, California. p. 298-301. Interpretive Summary: In the present study, we tested the utility of a DNA fingerprinting method called ‘inter-simple sequence repeat-polymerase chain reaction' (ISSR-PCR) in distinguishing geographic populations of the smoke-tree sharpshooter (STSS) and several natural enemies of both the STSS and the glassy-winged sharpshooter (GWSS). The method is extremely sensitive. Previously, using this method, we determined the origin (Texas) of the GWSS that invaded California. In addition, we have utilized this procedure to discover a cryptic species complex in Gonatocerus morrilli, a primary natural enemy or egg parasitoid of the GWSS. The results demonstrated that geographic populations of the STSS are genetically distinct. In addition, the ISSR-PCR method was able to genetically distinguish each natural enemy species. Each natural enemy species was found associated with a unique banding pattern. These results are important to biological control programs because they allow for the rapid distinction of natural enemies in the field.
Technical Abstract: In the current study, we tested the utility of the inter-simple sequence repeat-polymerase chain reaction (ISSR-PCR) DNA fingerprinting method in distinguishing geographic populations of the smoke-tree sharpshooter (STSS) (Homalodisca liturata Ball) and in distinguishing several egg parasitoid species in the genus Gonatocerus. Four geographic populations of the STSS were analyzed and they included: near Central (Olgilby Rd.), CA; Riverside CA; Imperial CA; and Phoenix, AZ. Five unique or population-specific markers were identified in the population from Riverside with minor genetic variation within the population. Another five population-specific markers were identified in the rest of the STSS populations (near Central and Imperial, CA, and Phoenix, AZ). Extensive genetic variation was detected in these STSS populations. Population-specific markers are an indication of subdivided populations and decreased gene flow. The following Gonatocerus ((Hymenotpera: Mymaridae) egg parasitoid species were analyzed: G. triguttutas (TX), G. morrilli (CA), G. ashmeadi (CA), G. fasciatus (LA) G. metanotalis (Argentina), near G. ashmeadi (Argentina), near G. triguttatus (Argentina), and G. tuberculifemur (Argentina). Each Gonatocerus species was associated with a unique ISSR-PCR banding pattern. In general, not much variation was seen within each species. Some variation was seen in G. tuberculifemur, while extensive variation was seen in G. fasciatus. The current results confirm the utility of using the sensitive ISSR-PCR method to distinguish geographic populations of the STSS and to distinguish several egg parasitoid species in the genus Gonatocerus. Rapid distinction of egg parasitoid species will speed up the identification process in a biological control program, thus saving time and cost.