Life History Studies of Homalodisca vitripennis (Hemiptera: Cicadellidae), a Vector of Pierce's Disease of Grapevine
Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae) vectors Xylella fastidiosa, a bacterium causing Pierce's disease in grapevine. The development and reproductive biology of this economically important insect species were studied under greenhouse and laboratory conditions during the spring-summer and fall-winter and at different rearing densities. The greenhouse wits heated during the cool months to match summer temperatures and photoperiods were enhanced artificially. Longevity wits affected by sex and season, with winter individuals living significantly longer than summer males (6.5-fold) and females (two-fold). Vitellogenesis was delayed in fall female H. vitripennis and a higher variability in lifetime fecundities wits also observed. Longevity and the factors influencing it such as environmental conditions and availability of food sources are key factors determining fecundity in H. vitripennis. Offspring performance (developmental time, survival) wits moderate during the cool months, although development of nymphs to adulthood was approximate to 13% greater. Rearing densities affected developmental time, survival, and egg production. Egg production per capita was higher in winter adults and the largest egg output was obtained at a rearing density of 100 nymphs per cage. Data presented herein Suggest that nymph and adult H. vitripennis have evolved to ensure that only resistant stages are exposed to seasonal hazards. Captive adult females entered reproductive diapause in the fall as wild females Would and despite warm greenhouse temperatures and long photoperiods and nymphal development decreased three- to six-fold during the fall-winter depending on rearing densities. These traits may be critical for the species to perpetuate in its native range.