March 24, 2015 Leave a comment
Every good wine student knows this: The glassy winged sharpshooter is a vector responsible for spreading Pierce’s Disease, and as such, is a known threat to commercial viticulture.
I’m right, aren’t I? You knew that? You have probably answered that question correctly on an exam, or even discussed the little guy fairly intelligently amongst your wine-loving friends.
But do you even understand what a vector is? (Hint: a vector is an insect that spreads disease.) And how well do you really know our friend with the glassy wings? Read on for a little insect insight!
The glassy winged sharpshooter is a common type of insect known as a leafhopper. There are over 20,000 different species of leafhopper, and they reach all over the world. Leafhoppers are closely related to, and share their insect family name – Cicadellidae – with cicadas and treehoppers, but are only distantly related to grasshoppers.
All members of the leafhopper family – who go by the nickname of “hoppers” – are plant feeders that feast on the sap of grass, shrubs, or trees. Their hind legs are built for jumping and they do just that – hopping from leaf to leaf, blade to blade, or tree to tree, inserting their needle-like mouths into the plants to lap up the juice. Hoppers are considered pests in many places as they can dehydrate the plants they feed on, causing havoc not just to grapes but to over 100 different plants all over the world, including oak trees, citrus trees, apple trees, and even coffee plants.
The name “sharpshooter” is used to refer to a group of large leafhoppers in the Proconiini branch of the family tree. In order to get enough nutrients, these insects filter a large volume of liquid sap through their digestive systems. Much of the excess water is then “squirted” forcibly away from the insect’s body in a fine stream – thus, the nickname “sharpshooter.” (I was hoping it was something a bit less gross, but there you have it.)
The glassy-winged sharpshooter is about ½ inch (12mm) long and has large, translucent (“glassy”) smoky-brown wings with red veins. They are native to the South America, and migrated to California from the southeastern United States. They were not always considered a serious pest in the past; but once introduced to Southern California it became a serious threat to viticulture due to the ease and rapidity with which it can spread the bacteria that causes Pierce’s disease. Once the sharpshooter has acquired the bacteria, it will remain infectious for the rest of its life.
The glassy winged sharpshooter remains a serious threat to viticulture in California and beyond. Due to its coloration, it is difficult to see in nature, despite its size. “Bug spotting” programs are underway in parts of California to help identify and prevent further infestations. Plant nurseries must confirm that their plants are “sharpshooter-free” and everyone is on the lookout. School children are taught to spot “sharpshooter rain” and many Californians are encouraged to have yellow sticky traps in their yards. Anyone who thinks they spot a sharpshooter is encouraged to call a hotline.
In the case of minor infestations, biological controls are used, including the introduction of various bugs – such as small wasps, spiders, and the praying mantis – that feed on the eggs. Chemicals (pesticides) are used in more extreme cases, but some of the more effective chemicals are also damaging to the wasps that help control the sharpshooters.
In other parts of the world, the glassy winged sharpshooter causes havoc by spreading phoney peach disease, oleander leaf scorch, and citrus X disease. The danged little glassy winged sharpshooter, it seems, remains a serious pest.
To learn more, and to see a picture of the glassy winged sharpshooter, visit the website of the Applied Biological Control Research Department at UC Riverside.
The Bubbly Professor is “Miss Jane” Nickles of Austin, Texas… email@example.com