Gill's mealybug, Ferrisia gilli
Gill's mealybug (Ferrisia gilli ) is an important mealybug recently established on grapes in El Dorado County. It is found on pistachios in the Southern San Joaquin Valley but is not known to be widespread on grapes in other areas of the state. As an adult, Gill's mealybug is relatively large (2-5 mm) with a lot of fine waxy filaments, making it fairly easy to identify with a hand lens. Gill's mealybug bears live crawlers, while Grape mealybug oviposits eggs under the bark of the trunk.
From 2008-2011 with funding from the American Vineyard Foundation and Viticulture Consortium West, local research on the biology and management of Gill's mealybug was conducted in the foothills. Key findings include:
- Gill’s mealybug completes 2 full generations in the foothills.
- Early in the season (May) Gill’s mealybug is best found under bark on old spurs and at the base of new emerging shoots. This is important for monitoring and making insecticide treatment decisions in late June.
- Treatments timed for the crawler/nymph stage out on leaves were targeted for late June-early July.
- Cluster damage ratings showed that this pest appears similar to grape mealybug-if left untreated it can build to undesirable damage. We observed up to 42% of the clusters in untreated plots had Gill’s mealybug, and 11% of these were rated either a “2” (more than ten mealybugs) or “3” (unacceptable damage).
- Insecticide treatments timed for the crawler stage with buprofezin (Applaud), spirotetramat (Movento), and acetamiprid (Assail) appeared effective. If populations are heavy and crawler emergence is spread out, two treatments of Applaud or Assail may be necessary to achieve adequate control.
- Parasitized Gill’s mealybugs were found at every site, however, numbers of mummies were very low in treated plots. We recommend every grower leave a small section untreated to preserve parasitoid activity.
- Gill’s mealybug continues to be found at vineyards in the area. We estimate at least 300 acres of grapes have the Gill’s mealybug in a portion of the vineyard.
View presentation on Gill's mealybug at the 2010 Wine Grape and Wine Research Symposium