Elizabeth Deyett

2017 Devirian Scholarship Award

The Grape Expectations: Discovering Alternative Strategies for Pest Management

Global climate change and rise in population pose a great threat to both our agricultural system and food security. As regions grow warmer, insect populations increase and begin to migrate and invade new production areas, affecting agricultural productivity, and viability. To keep up with humanity's food consumption, agriculture has turned to the use of copious amounts of pesticides to avoid pathogens and increase crop yield. These pesticides have been linked to a number of environmental and ecosystem changes ranging from amphibian population declines to groundwater contamination. Pesticide residues also build up in food, becoming a potential hazard to the consumer. It’s estimated that pesticides have been linked to $15 billion dollars in medical bills in 2005, as well as incalculable environmental costs just within the US. Additionally, resistance to pesticides continues to grow, causing farmers to increase their usage. The need for novel innovative and alternative methods to implement for sustainable agricultural management, both for food security and environmental health, is accelerating as this issues become more prominent. In the last decade, numerous microbiome studies have shown the beneficial impact microbes have on both plant and animal health. This suggests that microbes can be used as an alternative or in addition to crop management strategy, reducing harmful pesticide build-up.

To better understand the highly dynamic microbial ecosystems in agriculture, my work focuses on grapevines and the common bacterial pathogen Xylella fastidiosa. Xylella fastidiosa (Xf) is a cosmopolitan pathogen affecting major economic crops including grape, citrus, almond and olive. This xylem dwelling bacterium is spread by sharpshooters insects and is capable of developing into Pierce’s disease (PD), where the pathogen obstructs the xylem, leading to the death of the plant. A class of sharpshooters have recently been introduced in southern California and global warming has expanded their geographical range to northern California. This brings the insect close to the heart of winegrape production, in Napa and Sonoma valleys. These sharpshooters are more efficient vectors of the disease and, if they become established, would have a devastating effect on the wine industry. The only management strategy currently for PD is controlling the vector through pesticides. In grapevines, Xf is responsible for $92 million a year in lost revenue. My project sets out to understand the pathogen-microbiome-plant interactions using PD and grapevine as a model and establishing ways to manipulate this natural interaction to provide optimal benefit to the host.

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