|Luft Albarracin, Erica|
|De Leon, Jesus|
Submitted to: Biocontrol
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/29/2011
Publication Date: 6/3/2011
Citation: Logarzo, G.A., Virla, E.G., Luft Albarracin, E., Triapitsyn, S., Jones, W.A., De Leon, J.H., Briano, J. 2011. Host range of Gonatocerus sp. near tuberculifemur Clade 1 in Argentina an egg parasitoid newly associated to the glassywinged sharpshooter Homalodisca vitripennis (Hemiptera:Cicadellidae)and candidate for its biocontrol. Biocontrol. Online. Interpretive Summary: The leafhopper glassy-winged sharpshooter (GWSS) is an effective vector of a plant bacterium that produces Pierce’s disease in grapes, which causes plants’ death. Indigenous to the southeastern United States and northeastern Mexico, this leafhopper was first discovered in southern California in 1989 and now poses a serious threat to the important wine and table grape industry. Control measures mostly consist of the use of pesticides, removal of key non-crop host plants, restriction of plant movement from infested areas and biological control. Classical biological control represents a promising method to reduce current populations as well as hinder the insects’ range expansion to new areas. However, the release of 6 biocontrol agents native to U.S.A. in the last ten years has not, so far, exerted sufficient levels of control to reduce Pierce´s Disease transmission. Owing to the low levels of control by native agents released against GWSS in California, egg parasitoids of leafhoppers in South America closely related to GWSS were studied to use them against the pest. Our goal was to search for parasitoids in climates and habitats matching those of currently invaded and threatened areas by GWSS in California. This article reports the results of laboratory and field specificity studies in the native range of the egg parasitoid in Argentina, providing the basis for a biological control program against GWSS.
Technical Abstract: The South American egg parasitoid Gonatocerus sp. near tuberculifemur “Clade 1” (G. sp. “Clade 1”) (Hymenoptera: Mymaridae) is a new association of the glassy-winged sharpshooter Homalodisca vitripennis (Germar) (Cicadellidae) and a candidate for its biological control in California, USA. In Argentina, G. sp. “Clade 1” was screened in the laboratory (no-choice tests) and in the field (multiple choice tests) with eggs of 32 Auchenorrhyncha host species and another four potential hosts unrelated to sharpshooters. In no-choice assays, it parasitized only eggs within the leafhopper tribe Proconiini. In contrast, in the long term field tests, it emerged not only from eggs of the Proconiini but also from two species of Cicadellini at low numbers (five wasps out of 698 exposed eggs). Two interpretations arise from the results: 1) Host associations of G. sp.“Clade 1” are restricted to the Proconiini whereas field parasitization of the Cicadellini species were false positive, or 2) G. sp. “Clade 1” parasitizes also some Cicadellini species and its rejection in the laboratory was a false negative. Both interpretations are discussed. Insect motivation could be the explanation for the negative results in the no-choice tests. On the other hand, in the more natural field situations, the host selection process and oviposition behavior should not have been affected and host range would be more realistic. The parasitism of the Cicadellini species would be indicative of a potential non-target effect on the sharpshooters in the USA.