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ARS Home » Pacific West Area » Maricopa, Arizona » U.S. Arid Land Agricultural Research Center » Pest Management and Biocontrol Research » Research » Publications at this Location » Publication #201322

Title: Dispersal and movement of the glassy-winged sharpshooter and associated natural enemies in a continuous, deficit-irrigated agricultural landscape

Author
item Groves, Russell
item JOHNSON, MARSHALL
item Hagler, James
item LUCK, ROBERT

Submitted to: CDFA Pierce's Disease Control Program Research Symposium
Publication Type: Proceedings
Publication Acceptance Date: 11/27/2006
Publication Date: 11/27/2006
Citation: Groves, R.L., Johnson, M.W., Hagler, J.R., Luck, R. 2006. Dispersal and movement of the glassy-winged sharpshooter and associated natural enemies in a continuous, deficit-irrigated agricultural landscape. CDFA Pierce's Disease Control Program Research Symposium, Nov 27-29, 2006, San Diego, CA, pp. 8-10.

Interpretive Summary: A combination of field and laboratory experiments were conducted to advance our understanding of the operative host-plant factors utilized by adult glassy-winged sharpshooter (GWSS) and associated natural enemies as long-range cues to locate feeding and oviposition hosts in a complex agricultural landscape. Specifically, the influence of different irrigation treatments implemented in orange groves on GWSS and natural enemy population dynamics was investigated. Dispersal and population dynamics of GWSS were monitored under continuous irrigation deficits receiving 60%, 80%, and 100% of their normal irrigation treatment. Orange trees exposed to the 60% water treatment had warmer leaves, significantly higher xylem matric potential, and fewer adult and immature GWSS than experimental trees exposed to the 80% and 100% water treatments. Identifying how the dispersing lifestages of GWSS locate and exploit specific host species will begin to provide the necessary information required to develop strategies for control of this highly mobile insect and further to limit the spread of Pierce’s Disease movement into susceptible crops.

Technical Abstract: A combination of field and laboratory experiments in this study have been designed to advance our understanding of the operative host-plant factors utilized by adult glassy-winged sharpshooter (GWSS) and associated natural enemies as longrange cues to locate feeding and oviposition hosts in a complex agricultural landscape. Specifically, a second year offield studies have been conducted to determine the influence of continuous deficit irrigation regimes implemented in sweet orange cv. 'Valencia' oranges on the population dynamics ofGWSS and other associated natural enemies. Dispersal and population dynamics of GWSS were monitored under continuous irrigation deficitss receiving 60%, 80%, and 100% of evapo-transpiration (ETc) rates. Similar to the results obtained in our 2005 season, citrus trees irrigated at 60% ETc had warmer leaves, significantly higher xylem matric potential, and fewer adult and immature GWSS than experimental trees irrigated with 80% and 100% ETc. Mean numbers of adult and nymphal GWSS collected from beat samples and observed in visual inspections were numerically higher in the 80% versus 100% ET c treatments. Caged experiments using sweet orange cv. 'Washington navel' and avocado cv 'Hass' maintained under different continuous deficit irrigation illustrated GWSS population shifts that occurred between plants. Adult GWSS showed a preference for contact with surplus-irrigated plants of both species compared with plants under continuous deficit irrigation, with a stronger response evident in the avocado trials. During preliminary nutrition trials with overwintered adults, GWSS that landed on plants showed a slight preference for settling on plants fertilized with ammonium versus averaging over the 3 trials. An olfactometer system for studying the response of GWSS to host-plant volatiles has been built and the airflow dynamics adjusted to equally integrate odor fields from humidity or volatile sources. However, evaluation of the data (number of insects landing on the target) to date shows no conclusive differences among a variety of treatments, suggesting that GWSS may not use olfactory cues during host location, or that olfaction is used only in conjunction with visual cues.Identifying how the dispersing lifestages of GWSS locate and exploit specific host species will begin to provide the necessary information required to develop strategies for control of this highly mobile insect and further to limit the spread of XI movement into susceptible crops.