- Winter 1995 "Update" Newsletter Article -
IPM student tracks habits of parasitic wasps, spiders
by Mark A. Mayse, Professor
Department of Plant Science and Mechanized Agriculture
From CATI Publication #950101
Copyright © 1995. All rights reserved.
During 1994 our research program received financial support from the American Vineyard Foundation and E & J Gallo, along with in-house grants from CSU, Fresno's California Agricultural Technology Institute and the recently initiated fund for Research, Creative and Scholarly Activities.
We also wish to acknowledge graduate students Debbie Dexter-Mendez and Julia Tinker for their integral roles in our Grape IPM Program.
Some of the studies conducted this year included the following:1) Emopathogenic Nematodes for Control of Omnivorous Leafroller (OLR) - a million insect parasitic nematodes per grape cluster were meticulously applied by hand sprayer to a vineyard block in Livingston, California, heavily infested by OLR larvae. Data collected at 3-, 7-, and 10-day post-treatment intervals revealed essentially zero percent infection/mortality of OLR larvae due to nematodes. Clearly, such dramatically unequivocal results provide limited justification to continue this research project.
2)Population Patterns of Hymenopteran Parasitoids -Five different techniques were used to sample adult parasitic wasps in vineyards near Ripperdan, California and at CSU, Fresno: yellow sticky cards, canopy shake, pitfall trap, malaise trap, and cardboard banding. With sticky cards, parasitoid counts were five times higher at CSU, Fresno (4000) than at Ripperdan (800), while malaise trap data were nine times greater at Ripperdan (135) than at CSU, Fresno (15). At both field sites, Anagrus wasps comprised some 95 percent of all parasitoids collected on sticky cards. Relatively large numbers of wingless scelionids (parasitiods of carabid eggs?) were collected in pitfall trap samples.
3)Reliability of Sap Brix Readings in Predicting Leafhopper Densities -Data were collected from Ripperdan and CSU, Fresno in several cultivars at vineyard edges and middles, using young and old leaves, along with blade tissues and petioles, and with two replicated for each sample. In addition to measuring soluble solids with a refractometer, counts were taken by direct observation for leafhopper nymphs (VLH and WGLH), spiders and green lacewing eggs.
4)Field Ecology of Key Spider Species -Two workgroup sessions on "Spiders in Vineyards" were held this year (at CSU, Fresno in March and at the UC Kearney Agricultural Center in October), providing outstanding opportunities for information exchange and research coordination. We are currently formalizing plans for cooperative publication of a Field Guide to Spiders in Vineyards with colleagues at the Kearney center.
5)Long-term Optimal Viticulture Systems Projects -A long-term project investigating conventional and organic viticultural production systems has been initiated at CSU, Fresno. Cover crops were planted this fall, and data collection for various arthropods (especially spiders and parasitoids) has recently been initiated. In addition, a newly-planted Merlot block in Mendocino County is the site for another long-term comparison of different grape production and protection practices beginning this fall.{ page top }