|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., Morgan, D. 2005. Small scale post-release evaluation of a Gonatocerus morrilli program in California against the glassy-winged sharpshooter: Utility of developed molecular diagnostic tools. Proceedings of CDFA Pierce's Disease Control Program Research Symposium, December 5-7, 2005, San Diego, California. p. 306-309. Interpretive Summary: Previously we discovered a cryptic species complex in Gonatocerus morrilli, a primary egg parasitoid or natural enemy of the glassy-winged sharpshooter (GWSS). We developed molecular diagnostic markers that distinguised the two cryptic species. One species is from Texas, the origin of the GWSS that invaded California (CA) and the other is from CA. The CA species co-evolved with the smoke-tree sharpshooter and the Texas species co-evolved with the GWSS. Based on the origin of the GWSS, it is imperative to collect natural enemies of the GWSS from TX. In the current study, we tested the utility of the two developed molecular diagnostic markers to evaluate the establishment of G. morrilli in CA. The current study demonstrated that the developed markers were successful at distinguishing the native and the imported G. morrilli. The results showed that imported G. morrilli imported from TX and Mexico (MX) did not establish in CA. Further investigation demonstrated that the TX/MX G. morrilli did not establish due to the fact that the original culture that was used to rear and release these natural enemies was contaminated with the native G. morrilli CA species. The results using these molecular diagnostic markers showed that what was being released in CA was the native CA species. The current study confirmed the utility of the developed molecular diagnostic markers at monitoring the establishment of this natural enemy and also will allow us in the future to monitor natural enemy colonies to eliminate unwanted species. This molecular technology is imperative to the success of the biological control program in CA.
Technical Abstract: Previously we discovered a cryptic species complex in Gonatocerus morrilli (Howard) and developed molecular diagnostic markers that distinguished the two cryptic species. In the current study we tested the utility of the two developed molecular diagnostic markers to evaluate the establishment of G. morrilli in California. In the two cryptic species, the size of the internal transcribed spacer 2 region (ITS2) varies by about 212 base pairs; the Texas G. morrilli species is associated with a size of about 851-853 base pairs and the California G. morrilli (nov.) species with a size of about 1063-1067 base pairs. Secondly, the two cryptic species do not share any inter-simple sequence repeat-polymerase chain reaction (ISSR-PCR) bands or markers. Initially, releases were made from what was thought to be a Mexico culture, but contamination was suspected to have occurred from a Texas culture and therefore, the culture was named "TX/MX". Post-released collections from years 2002 and 2003 were made from the following locations: San Juan Capistrano, Glen Ivy, Pauma, Temecula, and San Marcos. Amplification of the ITS2 rDNA fragments demonstrated that all or 100% of the randomly chosen individuals (125 total) were of the California ITS2 genotype and none were of the Texas ITS2 genotype. ISSR-PCR DNA fingerprinting of the TX/MX colony along with native California and Texas G. morrilli species demonstrated that the TX/MX ISSR-PCR banding pattern was superimposable to that of the California G. morrilli (nov.) species. The results demonstrated that the TX/MX colony was contaminated with the California species, indicating that what was being released in California was California’s own native species. Therefore, this is why screening with the ITS2 fragment detected only the California ITS2 genotype. The present results confirm the utility of the two developed molecular diagnostic methods in monitoring the success of the G. morrilli biological control program in California. In addition, this molecular technology will allow us to monitor egg parasitoid colonies to eliminate unwanted species.