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Landscapes from a two-year ecological study of wine grape vineyards in California.

Agroecologist and University of Hawaiʻi West Oʻahu Assistant Professor of Sustainable Community Food Systems, Albie Miles and University of California Berkeley colleagues conducted a two-year ecological study of wine grape vineyards in California to inform the development of new strategies for natural pest control and pesticide reduction. The objective of the study was to determine the influence of vine vigor (crop nutrient status and growth rates) and local-scale and landscape-scale habitat quality on biological control of the Western grape leafhopper by its key natural enemies, Anagrus wasps.

Their findings indicate that, in this agroecosystem, landscape diversity—the quality and abundance of surrounding native ecosystems—mediated pest populations and outweighed the influence of local-scale habitat provisioning (see images above). The authors conclude that pest populations were best controlled by a combination of enhanced biologic control—driven by the quality of insect habitat in the surrounding landscapes—and low crop vigor, which is less attractive to the pest.

The implications of the findings suggest that the conservation of California native plant habitat, the selective planting of native plant species and the efficient management of crop nutrients (nitrogen fertilizer) can all contribute to enhanced natural pest regulation and a reduction in pesticide use.

The results were published in the article “Landscape diversity and crop vigor outweigh influence of local diversification on biological control of a vineyard pest,” in Ecosphere, a journal of the Ecological Society of America.

For full abstract and additional information on Miles, please visit UH West Oʻahu’s E Kamakani Hou.

E Kamakani Hou article

—By Leila Wai Shimokawa

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