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Glassy-winged Sharpshooter
The glassy-winged sharpshooter is a devastating new pest for California. While the pest is not a problem in the Southeast United States, since its migration into California in 1990, the glassy-winged sharpshooter population there has ballooned. It can now be found throughout southern California.
This pest is a concern to California agriculture because of its ability to transmit Xylella fastidiosa, a bacterium that causes a variety of plant diseases including Pierce's disease, which threatens California's wine and table grape industry. The glassy-winged sharpshooter flies further than native sharpshooters, making the possibility of the bacteriumís increased spread a serious agricultural threat.
The glassy-winged sharpshooter is about 0.50 of an inch (12mm) in length. Its color is dark brown to black with a black-and-yellow underside. It has yellow eyes, and the upper parts of the head and back are speckled with ivory or yellowish spots. The wings are transparent with reddish veins.
The glassy-winged sharpshooter feeds on a wide variety of plants. Scientists estimate that host plants for this sharpshooter include over 70 different plant species. Among the hosts are grapes, citrus, almond, stone fruit, and oleanders. Because of the large number of hosts, glassy-winged sharpshooter populations are able to flourish in both agricultural and urban areas.
Glassy-winged sharpshooters usually lay a mass of eggs on the underside of leaves. After the glassy-winged sharpshooter nymphs hatch, the remaining egg mass leaves a brown mark on the leaf's surface. The nymphs feed within the vascular system of the small stems on the plant where the eggs were deposited. After several moltings or transformations, the nymphs become adult glassy-winged sharpshooters.
The sharpshooter feeds on a plant by inserting its needle-like mouth parts into the plant's xylem (the water-conducting tissues in the plant). While feeding, the glassy-winged sharpshooter excretes small droplets of a watery excrement, often called "leafhopper rain." This excrement is messy and, when dry, gives plants and fruit a whitewashed appearance.
Its feeding method, along with its voracious appetite for so many different hosts, makes the glassy-winged sharpshooter a vector for the Xylella fastidiosa bacterium. Once it feeds on an infected plant, the sharpshooter carries the bacterium to the next plant and transmits the disease while feeding. This spread can continue from plant to plant. A plant that is not affected by any of the diseases caused by Xylella fastidiosa becomes a reservoir, holding the bacterium for other sharpshooters to pick up and carry to other plants.
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