|De Leon, Jesus|
Submitted to: CDFA Pierce's Disease Control Program Research Symposium
Publication Type: Proceedings
Publication Acceptance Date: 10/12/2004
Publication Date: 12/7/2004
Citation: De Leon, J.H., Jones, W.A., Morgan, D.J.W., Mizell, R.F., III. 2004. Sequence divergence in two mitochondrial genes (COI and COII) and in the ITS2 RDNA fragment in geographic populations of Gonatocerus morrilli, a primary egg parasitoid of the glassy-winged sharpshooter. In: Proceedings CDFA Pierce's Disease Control Program Research Symposium, December 7-10, 2004, San Diego, California. p. 322-325. Interpretive Summary: Gonatocerus morrilli is an egg parasitoid of the glassy-winged sharpshooter (GWSS). This primary egg parasitoid species is common in the southern United States and Mexico. A biological control program is currently in progress in California against the GWSS, which is a serious economic pest that transmits a strain of bacterium that causes Pierce's disease in grapevines. Accurate identification of natural enemies is critical to the success of classical biological control programs. This study uses sophisticalted genetic techniques to determine differences and similarities among different geographic populations of G. morrilli. The results will facilitate ongoing efforts to develop effective biological control programs for the GWSS.
Technical Abstract: The aim of the present study was to resolve the genetic relationships of geographic populations of Gonatocerus morrilli, a primary egg parasitoid of the glassy-winged sharpshooter. A phylogenetic approach was implemented by sequencing two mitochondrial genes (COI and COII) and the Internal Transcribed Spacer-2 (ITS2) region of several individuals per population. Two populations from Weslaco, TX (WTX) (collected at different times), one from Quincy, FL (QFL), two from California (CA) (Orange and San Diego counties), and an outgroup (G. ashmeadi) were analyzed. For all three sequence fragments, percentage sequence divergence (%D) (as measured by genetic distance), the results demonstrated that both the WTX and QFL populations were closely related; in constrast, the %D between WTX and CA fell within the range of the outgroup, G. ashmeadi. For all three sequence fragments, Nieghbor-Joining distance trees separated the CA and WTX and QFL populations into two distinctive clades (A and B). The topology of the clades in each case was supported by very strong bootstrap values, 100% in the three sequence fragments (COI, COII, and ITS2). The present molecular phylogenetics results provide strong evidence that G. morrilli from California may be a different species. The findings of the present study are important to the glassy-winged sharpshooter/Pierce's disease biological control program in California.