UC Berkeley

The research tested the natural enemies hypothesis in an attempt to explain why lower pest densities are observed in some diversified farming systems. The research evaluated the influence of floral resource provisioning (FRP) and chemical ecology strategies on biological control of Erythroneura leafhoppers (Hemiptera: Cicadellidae) and Planococcus mealybug (Hemiptera: Pseudococcidae) in California vineyards. Field and laboratory studies quantified the impacts on crop damage, pest and natural enemy abundance, and natural enemies fitness theorized to be enhanced through floral resource provisioning in agroecosystems. Multiple two-year studies measured the impact of intercropping three flowering ground covers, lacy phacelia (Phacelia tanacetifolia), bishop's weed (Ammi majus), and common carrot (Daucus carota) on biological control of leafhoppers and vine mealybug by the parasitoids Anagrus spp. (Hymenoptera: Mymaridae) and Anagyrus pseudococci (Hymenoptera: Encyrtidae). Using identical intercropping treatments, the research included three large scale and fully replicated research designs located in the central San Joaquin, the northern San Joaquin, and the Napa Valley of California. Laboratory studies quantified the impacts of FRP on the fitness of Anagyrus pseudococci, a key parasitoid natural enemy of vine mealybug. The central San Joaquin Valley field study measured the impact of FRP and pheromone based mating disruption on biological control of vine mealybug. The northern San Joaquin Valley field study measured the impact of FRP and methyl salicylate on biological control of Erythroneura leafhoppers. The Napa Valley field study measured the effect of methyl salicylate alone on biological control of Erythroneura leafhoppers.