Dispersal of Homalodisca vitripennis (Homoptera: Cicadellidae) from a point release site in citrus

Authors: Blackmer, Jacquelyn; Hagler, James; SIMMONS, G - USDA-APHIS PHOENIX, AZ; Henneberry, Thomas

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/1/2006
Publication Date: 12/6/2006
Citation: Blackmer, J.L., Hagler, J.R., Simmons, G.S., Henneberry, T.J. 2006. Dispersal of Homalodisca vitripennis (Homoptera: Cicadellidae) from a point release site in citrus. Environmental Entomology 35(6):1617-1626.

Interpretive Summary: The glassy-winged sharpshooter is an important vector of a bacterium that has caused substantial losses in the viticulture and ornamental industries in California. Management programs have been implemented to reduce population levels and limit the spread of this vector. However, there is a lack of information on the factors that influence this insect’s movement within and between host crops. Here we used a mass-mark-recapture (MMR) technique to examine the dispersal of glassy-winged sharpshooters in a mature orange grove. Insects were doubly marked with chicken or rabbit proteins and fluorescent pigments to enable monitoring over several weeks. Our objectives were to examine the reliability of protein markers relative to fluorescent pigments, determine how sharpshooter movement differed in a complex host-plant matrix from a previous study that examined movement in a simple host-plant matrix, and develop a better understanding of the biotic and abiotic factors that might influence sharpshooter dispersal. Recapture data were fit to a diffusion model and based on parameters generated with this model, dispersal distances were estimated in the orange grove. Estimated dispersal distances showed that 95% of the sharpshooters would be recaptured within 90 m of the release site after 72 h and within 114 m after 816 h. Flight activity was greatest between 1000 and 1400 h, and no flights occurred between 2000 h and 0600 h. Only temperature explained a significant amount of the variability in trap catch. Sharpshooters were rarely trapped when temperatures fell below 18 deg C.

Technical Abstract: The glassy-winged sharpshooter, Homalodisca coagulata (Say) is an important vector of Xylella fastidiosa, a bacterium that has caused substantial losses in the viticulture and ornamental industries in California. Area-wide management programs have been implemented to reduce population levels and limit the spread of this vector. However, there is still a lack of information on the factors that influence this insect’s movement within and between host crops. Here we used a mass-mark-recapture (MMR) technique to examine the dispersal of H. coagulata in a mature orange grove. Insects were doubly marked with chicken or rabbit immunoglobulin G (IgG) proteins and fluorescent pigments to enable monitoring over several weeks. Our objectives were to examine the reliability of IgG protein markers relative to fluorescent pigments, determine how sharpshooter movement differed in a complex host-plant matrix from a previous study that examined movement in a simple host-plant matrix, and develop a better understanding of the biotic and abiotic factors that might influence sharpshooter dispersal. Recapture data were fit to a diffusion model and based on parameters generated with the diffusion model, dispersal distances were estimated in the orange grove. Linear regressions of recapture data with the diffusion model provided significant fits to the data in five out of six releases. Estimated dispersal distances showed that 95% of H. coagulata would be recaptured within 90 m of the release site after 72 h and within 114 m after 816 h. Flight activity was greatest between 1000 and 1400 h, and no flights occurred between 2000 h and 0600 h. Only temperature explained a significant amount of the variability in trap catch. Sharpshooters were rarely trapped when temperatures fell below 18 deg C.