Submitted to: CDFA Pierce's Disease Control Program Research Symposium
Publication Type: Abstract Only
Publication Acceptance Date: 10/25/2013
Publication Date: 12/16/2013
Citation: Krugner, R. 2013. Suitability of fertilized and non-fertilized eggs of Homalodisca vitripennis for the egg parasitoid Gonatocerus morrili. CDFA Pierce's Disease Control Program Research Symposium. p.11.
Technical Abstract: The glassy-winged sharpshooter (GWSS), Homalodisca vitripennis, is a key vector of Xylella fastidiosa, the bacterium that causes Pierce’s disease of grapevines and other diseases of high-valued crops in the Americas. GWSS invaded California in the late 1980s and continues to threaten the $4 billion grape industry. Control measures for GWSS in California include an area-wide insecticide (i.e., imidacloprid) application program and release of natural enemies, but, despite such efforts, the geographic distribution of GWSS continues to expand. Gonatocerus morrili (Howard) (Hymenoptera: Mymaridae) is a natural enemy used in California, USA to control GWSS. Virgin GWSS females deposit non-fertilized eggs, and mated females can exhaust sperm reserves for egg fertilization. However, nothing is known about Gonatocerus spp. performance when using non-fertilized GWSS eggs. Host age preference for oviposition and suitability of non-fertilized GWSS eggs for G. morrili reproduction were investigated. Gonatocerus morrili parasitized all ages of GWSS eggs (1 to 8 days old) regardless if the host egg was fertilized or not. However, parasitism rates and parasitoid emergence were reduced in older (> 5-day old) non-fertilized host eggs compared to fertilized eggs. In choice tests (fertilized versus non-fertilized eggs), parasitoids failed to emerge as adults from non-fertilized eggs more often than from fertilized eggs. The results indicate that non-fertilized eggs were accepted by G. morrili as suitable hosts for oviposition, but were relatively unsuitable for immature development compared to fertilized eggs.