Sunday, 17 November 2002 - 1:12 PM

This presentation is part of : Ten-Minute Papers, Subsection Cd. Behavior and Ecology (Session 2)

Host-plant selection and performance of the Glassy-winged sharpshooter on citrus

Carlos E. Coviella, Paul Flores, and Robert F. Luck. University of California, Department of Entomology, Riverside, CA

The Glassy-winged sharpshooter (GWSS), Homalodisca coagulata (Say) is the main vector of Pierce?s disease in grapevines. This disease has already inflicted heavy damage to certain areas in California. To provide information on the biology and ecology of this insect, information is needed about the population dynamics of the GWSS. Following a species? population dynamics requires a reliable method of estimating its field density over time and on different host plants. Using surplus military parachutes we cover citrus trees, and fog them to recover all GWSS stadia except eggs. We present data on density estimates for this insect in different host-plants. Our results show that adult GWSS shift between different Citrus host plants in different seasons. While in summer and fall there was no significant difference in GWSS densities between lemon and orange trees, both preferred hosts, in winter adult GWSS could be found almost exclusively on lemon trees. A second aspect of our research seeks to explain these shifts in host plant choice by investigating correlations between insect densities and host plants xylem chemistry. We use a specially designed Schölander bomb to measure xylem fluid hydrostatic pressure and to extract xylem fluid for chemical analyses. We use this technique to explore possible correlations between changes in GWSS density and reproduction on a given host plant and its relationship to physical and chemical properties of that plant. Data from laboratory experiments suggests there is a correlation between feeding rate and leaf aminoacid profile and amides content in the xylem fluid of the host plant.

Species 1: Homoptera Cicadellidae Homalodisca coagulata
Keywords: Pierce's disease

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