Oviposition and Flight Activity of the Blue-Green Sharpshooter (Hemiptera: Cicadellidae) on Southern California Wild Grape and First Report of Associated Egg Parasitoids

Abstract

Oviposition of Graphocephala atropunctata (Signoret) (Hemiptera: Cicadellidae), the blue-green sharpshooter, was assessed on wild grape, Vitis girdiana Munson, in southern California. Female blue-green sharpshooter preferred to oviposit into new growth, primarily succulent young grape tendrils and canes. The midrib and petioles of small grape leaves also were used for oviposition, but to a lesser extent. Mature canes, and medium- and large-sized leaves were not used for oviposition. Two parasitoids, Gonatocerus latipennis Girault and Polynema sp. (both Hymenoptera: Mymaridae) were reared from field collected blue-green sharpshooter eggs. Polynema sp. and G. latipennis constitute the first documented egg parasitoids of blue-green sharpshooter. Deployment of sentinel plants and reciprocal tests were implemented and further confirmed the parasitization of blue-green sharpshooter eggs by these two parasitoid species. Yellow sticky card trap catch of adult blue-green sharpshooter was significantly correlated to combined blue-green sharpshooter nymphal and Polynema sp. emergence in 2004, but not in 2005. A degree-day model was developed for onset of blue-green sharpshooter flight activity and emergence in the field.