SPATIAL POPULATION DYNAMICS AND OVERWINTERING BIOLOGY OF THE GLASSY-WINGED SHARPSHOOTER IN CALIFORNIAS SAN JOAQUIN VALLEY

• Author(s): Backus, Elaine; Daane, Kent; Groves, Russell; Johnson, Marshall; Son, Youngsoo;
• Abstract: The purpose of this project is to define specific environmental constraints that influence glassy-winged sharpshooter (GWSS) population dynamics and overwintering success. Experiments were conducted to determine effects of constant temperatures on the survival of GWSS adults for various exposure times under three different conditions: water-only, no water or host plant, and host plant. When only provided water, adults survived the longest (16.3 1.8 days) at 15()C, with the shortest longevities at 0 and 40()C (1.5 0.1 and 2.5 0.3 days, respectively). Overall, the longevity patterns implied that lack of a suitable host plant would result in greater reductions in survival at higher temperatures (e.g., = 25()C). When adults were provided with a preferred host plant (Frost Eureka lemon), percent adult survival was significantly influenced by temperature and exposure time with a significant interaction between time and treatment. Unlike the initial study where only water was provided, adult survival decreased drastically at low temperatures (0-10()C), while survival between 15-30()C averaged > 68%. Findings suggest that mortality at low temperatures could result from starvation or lack of feeding, and the critical threshold temperature required for ingestion lies between 10-15()C. In a third experiment comparing host plant presence and absence, 100% mortality occurred at 3, 21, 24 days exposure at 0, 5, and 10()C, respectively. This implies that GWSS adults cannot feed on a host plant at low temperatures (0-10()C), and further suggests that the threshold temperature for feeding falls between 10 and 15 ()C. Results from these experiments will be coupled with climatological data to help to spatially define where GWSS can be expected to persist in the agricultural landscape and identify where continued management efforts can be directed to limit introductions into currently non-infested areas.
• Publication Date: Dec 2005
• Journal: 2005 Pierce's Disease Research Symposium