Evaluation of grapevine as a host for the glassy-winged sharpshooter

Authors: Sisterson, Mark; Krugner, Rodrigo; Wallis, Christopher

Submitted to: CDFA Pierce's Disease Control Program Research Symposium
Publication Type: Abstract Only
Publication Acceptance Date: 10/11/2012
Publication Date: 11/28/2012
Citation: Sisterson, M.S., Krugner, R., Wallis, C.M. 2012. Evaluation of grapevine as a host for the glassy-winged sharpshooter. In: Pierce's Disease Research Progress Reports, California Department of Food and Agriculture. pp 12.

Interpretive Summary:

Technical Abstract: Grapevine was evaluated as a feeding and oviposition host for the glassy-winged sharpshooter. Two sets of experiments were conducted. The first set compared performance and preference of glassy-winged sharpshooter females for grapevine (cv. Chardonnay) versus cowpea (Vigna unguiculata cultivar black eye). Cowpea was used as a reference host plant species as previous studies have documented that glassy-winged sharpshooters readily use cowpea as a feeding and oviposition host. The second set of experiments compared performance and preference of glassy-winged sharpshooter females for X. fastidiosa-inoculated grapevine versus mock-inoculated grapevine. In choice tests comparing preference of females for grapevine versus cowpea, females were observed more frequently on grapevine than on cowpea with 78% of eggs deposited on grapevine. In no-choice tests with females confined to plant stems, females confined to cowpea stems produced 1.5 times more excreta than females confined to grapevine stems. Further, females confined to cowpea stems produced 1.6 times more mature eggs than females confined to grapevine stems. In no choice tests with females provided full access to plants, females produced similar numbers of eggs on grapevine and cowpea. As feeding affects egg maturation, differences in the results of no-choices tests with females confined to plant stems versus no-choice tests with females given full access to plants suggests that feeding site selection may be more important on grapevine than on cowpea. Collectively the results suggest grapevine is of similar quality and acceptability for adult feeding and oviposition as cowpea. Choice tests comparing preference of females for X. fastidiosa-inoculated grapevine versus mock-inoculated grapevine produced variable results. In choice tests conducted in 2011, females were observed more frequently on mock-inoculated grapevines than on X. fastidiosa-inoculated grapevines. In choice tests conducted in 2012, females were observed more frequently on mock-inoculated grapevines compared to X. fastidiosa-inoculated grapevines displaying severe Pierce’s disease symptoms, but females did not display any preference for mock-inoculated grapevines versus X. fastidiosa-inoculated grapevines that were asymptomatic or displayed minor symptoms of Pierce’s disease. In no-choice tests with females confined to grapevine stems, females on mock-inoculated grapevines produced numerically more excreta than females on X. fastidiosa-inoculated grapevines, although the difference was not significant. Collectively, results comparing preference and performance of glassy-winged sharpshooter females for X. fastidiosa-inoculated versus mock-inoculated grapevines suggest females prefer mock-inoculated grapevines but degree of preference may be related to disease severity. Disease severity may impact glassy-winged sharpshooter preference because plants with greater symptom severity may be of reduced host quality. Additional tests evaluating effects of disease severity on glassy-winged sharpshooter preference and performance are needed.