THE ROLE OF VARIETAL MIXTURES IN MEDIATING PEST CONTROL, YIELD, AND ECONOMIC SERVICES IN AGROECOSYSTEMS
Snyder, Lauren Denise
Agrobiodiversity can support ecosystem services that provide ecological, economic, and human nutritional benefits. Most efforts to capitalize on these services have focused on enhancing crop species diversity in the form of polycultures. While polycultures can provide numerous services, they can also present logistical challenges for farmers. One relatively under-explored form of diversification that may be more straightforward to implement is to enhance intraspecific crop diversity within a farm field by planting multiple varieties of the same crop species. Compared to different crop species, varieties of the same species are more likely to share agronomic traits that facilitate growing and marketing them together. While there is strong evidence that varietal mixtures can suppress pathogens and enhance crop yields, less is known about their ability to provide insect pest control services. Moreover, there is no empirical research on the performance of varietal mixtures across different landscape contexts, a factor known to influence the effectiveness of local-scale practices for pest control. Here, I investigate the potential for mixtures of Brassica oleracea varieties to provide profitable pest control services across different landscape contexts and elucidate the mechanisms underlying the effect of varietal mixtures on pest abundance and crop production. Chapter one provides an interdisciplinary synthesis of existing research on the capacity of varietal mixtures to provide pest control and yield services, strengthen agricultural resilience, and support human nutrition. In chapter two, I assess whether varietal mixtures of B. oleracea are a profitable pest management strategy on farms in New York State. I demonstrate the importance of accounting for landscape composition when implementing local-scale practices, as varietal mixtures can have both beneficial and detrimental effects on pest populations, depending on landscape context. This chapter also indicates that enhancing trait variation in mixtures can increase profitability, potentially through reduced pest pressure. Chapter three explores the mechanisms underlying the effects of B. oleracea mixtures on pest populations and crop production, and suggests that varietal identity, rather than diversity per se, drives these processes. Collectively, my work demonstrates the importance of measuring multiple services to thoughtfully design varietal mixtures that contribute to sustainable food systems and support farmer livelihoods.
agrobiodiversity; ecosystem services; human nutrition; pest control services; resilience; varietal mixtures
Power, Alison G.
Poveda, Katja Andrea; Thaler, Jennifer S.; Gomez, Miguel I.
Ecology and Evolutionary Biology
Ph. D., Ecology and Evolutionary Biology
Doctor of Philosophy
dissertation or thesis