This page contains the material submitted to the local paper - The Davis Enterprise - for Explorit Science Center's news column published in that paper on Fridays.

Over the years, Californians have learned about a growing number of invasive insects, from Mediterranean fruit flies to fire ants, that threaten the health of plants and/or animals. The latest insect to join this rogues gallery is the glassy-winged sharpshooter, which can infect plants with the deadly Pierce’s disease.

Tom Esser of the California Department of Food and Agriculture will give a free lecture entitled “California’s Control Program for Pierce’s disease and the Glassy-winged Sharpshooter” on Tuesday, at 7:30 p.m. at the Davis Senior Center, giving Davis residents a view from the front lines of the fight against this potentially devastating intruder.

Glassy-winged sharpshooters (Homalodisca coagulata) are relatively large (.5 in) leafhoppers that have partially transparent wings laced with red veins. The insect’s body is dark brown to black on top with a lighter underside; the upper portions of the head and back display ivory to yellow dots. Large white dots are often found on sharpshooters’ flanks; these are not part of the insect but rather are deposits of watery excrement.

Glassy-winged sharpshooters are native to the southeastern United States, but were first found in California in 1990. Currently, they are most common in Southern California, and have been identified in ten California counties.

Sharpshooters feed on a variety of ornamental and crop plants. They pose a particular threat to California’s famed wine industry due to their predilection for feeding on the stems of grape plants; in doing so they can not only cover the plant and surrounding ground with sticky excreta, but, more importantly, can infect the plant with Pierce’s disease.

Pierce’s disease is caused by Xylella fastidiosa, a bacterium transmitted from diseased plants to healthy ones by sharpshooters feeding on sap. X. fastidiosa is limited to plants’ xylem (the part of the vegetative vascular system that allows water to move up through the plant). Eventually the bacterium will block the xylem, leading to severely reduced water flow to the leaves.

Signs of water stress in affected plants generally begins in mid-summer, and increases through fall. Because of the bacteria-choked xylem, plants with Pierce’s disease can have a “scorched” appearance, and often display concentric zones of dead and discolored tissue. In addition to Pierce’s disease, X. fastidiosa also causes almond leaf scorch, alfalfa dwarf, oleander leaf scorch, and citrus variegated chlorosis.

Due to their ability to spread Pierce’s disease, tracking and eradicating glassy-winged sharpshooters is of major economic importance. Because there is no known cure for Pierce’s disease, severely infected vineyards often have to be torn out and subsequently replanted. The influx of glassy-winged sharpshooters into California has a very real potential to deal a heavy blow to the state’s famed wine industry.

The California Department of Food and Agriculture, with the help of the USDA and local agencies, is countering this problem with the Pierce’s disease Control Program. Tom Esser, a senior environmental research scientist, will outline the state’s plan to slow the spread of this pest at Explorit’s free lecture Tuesday.

Esser’s lecture “California’s Control Program for Pierce’s disease and the Glassy-winged Sharpshooter” will provide background information on the leafhopper, up-to-date information about its spread, and detailed information on the pest prevention program.

Presented by Explorit Science Center, this lecture will take place at the Davis Senior Center, 646 A Street in Davis. This lecture, as part of Explorit’sCutting Edge of Science Lecture Series, is free and open to the public. This and all lectures in this series are sponsored by Novo Nordisk Biotech, Inc. with additional support from the Davis Senior Center.

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