DISCOVERY OF A CRYPTIC SPECIES COMPLEX IN GONATOCERUS MORRILLI, A PRIMARY EGG PARASITOID OF THE GLASSY-WINGED SHARPSHOOTER

• Author(s): de Le?n, Jesse; Jones, Walker; Morgan, David; S?tamou, Mamoudou;
• Abstract: We investigated the differentiation and reproductive isolation among different geographic populations of Gonatocerus morrilli, an egg parasitoid of the glassy-winged sharpshooter (GWSS) (Homalodisca coagulata Say) (Homoptera: Cicadellidae), to confirm previous observations that there may exist a cryptic species complex. Two mitochondrial genes [cytochrome oxidase subunits I (COI) and II (COII)] and the internal transcribed spacer region 2 (ITS2) of several individuals per population were sequenced. Gonatocerus morrilli populations from Texas (TX), Florida (FL), California (CA), and an outgroup (G. ashmeadi) were analyzed. For comparison, a population from Argentina identified as near G. morrilli (=G. annulicornis) was also included. For all three sequence fragments, percentage sequence divergence (%D) demonstrated that both the TX and FL populations (TX/FL) were closely related and therefore, determined to be the same species; in constrast, the %D between TX/FL and CA fell within the range of the outgroup, making the CA population a novel species (nov. sp. G. morrilli). Neighbor-joining distance trees clustered the TX/FL and CA populations or species into two well supported distinctive clades. The G. morrilli (nov. sp.) was more closely related to G. annulicornis than to the TX/FL species. Mating studies demonstrated that the populations or species from CA and TX were reproductively incompatible, producing no female offspring in both direct and reciprocal crosses; whereas, the heterogamic crosses between TX and FL produced fertile offspring and relative compatibility indices similar to the homogamic crosses. These results are important to the PD/GWSS biological control program in California.
• Publication Date: Dec 2005
• Journal: 2005 Pierce's Disease Research Symposium