Managing Vineyard Insect and Mite Pests
Western Grapeleaf Skeletonizer
Western grapeleaf skeletonizer (Harrisina brillians) is a pest of grapes that periodically defoliates vineyards. It is a native of the southwestern United States and northern Mexico.
Symptoms
The larvae of the western grapeleaf skeletonizer feed on the lower leaf surface leaving a brown, necrotic, skeletonized leaf tissue. This gives leaves a whitish paper-like appearance; eventually the entire leaf turns brown.
Life Cycle
Pupae pass the winter in cocoons on the ground in debris. In late spring, adult moths emerge and eggs are deposited in yellow clusters on lower leaf surfaces.
Monitoring
The moths are active during the day and so will be very easy to detect when populations are significant (See Figure 22.23).
Cultural Practices
During the dormant season remove mummy clusters and debris on the ground.
Biological Pest Control
A number of parasites prey upon western grapeleaf skeletonizer larvae. Among these are the tachinid fly (Ametadoria misella) and the braconid wasp (Apanteles harrisinae). See Appendix J, Beneficial Insects, Mites, and Spiders.
Biorational Pest Control
Microbials
Microbial insecticides Success, SpinTor, and Entrust can be used which contain the active ingredient spinosad, which is derived from a naturally occurring soil dwelling bacterium called Saccharopolyspora spinosa.
Chemical Pest Control
Standard chemicals for controlling western grapeleaf skeletonizer include Intrepid (methoxyfenozide), Altacor (chlorantraniliprole), Belt (flubendiamide), and Delegate (spinetoram). Insecticides used for controlling western grapeleaf skeletonizer in vineyards are presented in Appendix K, Insecticides Registered for Use in Vineyards.
Applying Control Materials
In areas where western grapeleaf skeletonizer does occur, granulosis virus usually keeps populations below economically damaging levels.
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