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Cornell University

Adeline Yeh wins Dyson Best Ph.D. Dissertation Award

Cornell University DEEP-GREEN-RADAR Research Associate D. Adeline Yeh is the recipient of the 2022 Dyson Best Ph.D. Dissertation Award for her Ph.D. Dissertation entitled "Three Essays on Economic Issues Confronting the Fresh Produce Sector".

Adeline's dissertation focuses on investigating decision-making in food value chains, including consumer preferences and food choices; producer pest management decision-making under uncertainty; and supply chain dynamics. A better understanding how producers and consumers make decisions is important for promoting sustainable food production; and for designing policies and institutions so that the decisions consumers and producer make lead to sustainable outcomes that maximize net benefits to society. Adeline's research therefore has important implications for food, agriculture, sustainability, decision-making, policy, and society.

In one paper, Adeline uses sophisticated techniques in bioeconomic modeling, dynamic optimization, Bayesian statistics, and dynamic structural econometric modeling to tackle an important issue in agricultural economics: sustainable pest management. In particular, she analyzes sustainable Spotted Wing Drosophila (SWD) pest management under uncertainty by conducting a dynamic bioeconomic analysis of lowbush blueberry production using a unique dataset of 92 lowbush blueberry farms in Maine. Spotted Wing Drosophila (SWD) is an invasive pest that has resulted in large management costs for berry growers in the U.S.

Adeline uses two complementary approaches to investigate the optimal SWD-targeted management strategy, the resulting welfare changes, and grower behavior. First, she develops a numerical bioeconomic finite-horizon dynamic programming problem to solve for the dynamically optimal management strategy, and to compare the predicted optimal decisions with actual decisions made by growers. Second, she builds upon her numerical bioeconomic model to develop a dynamic structural econometric model that accounts for the unobservable factors that arise when growers make actual choices in order to estimate the structural parameters. Her dynamic structural econometric model enables her to ascertain what parameters, beliefs, and perceptions would rationalize the decisions growers actually made. She is then using her dynamic models to simulate the effects of counterfactual scenarios on grower decisions and to analyze incentives for growers to adopt sustainable management strategies.

For Maine lowbush blueberry growers, a sustainable pest management alternative is to harvest earlier to avoid the late season high pest pressure. Adeline's results suggest that early harvesting can be part of an optimal management strategy when SWD population is high; and for weeks with a low SWD population, spraying insecticide is also not optimal in most cases. In contrast, the actual spraying and harvesting decisions of growers are not optimal: the probability of spraying in the observed data is much higher than is optimal, and the actual harvest decisions tend to be later than optimal. The average deadweight loss, which arises from differences between growers' actual pest management strategy and the optimal pest management strategy, is $137 per acre.

Results from Adeline's dynamic structural model show that the actual behavior of growers is rationalized by a very high perceived spray cost and as well as a high perceived yield loss from infestation from medium-high levels of SWD. Furthermore, even after conditioning on growers' beliefs, her results still show a deadweight loss to actual pest management decisions. In particular, she finds that, even given growers' beliefs and perceptions, and in contrast to their actual spraying and harvesting decisions, the optimal SWD strategy still tends to include early harvesting and very little if any spraying.

Adeline's research has important implications for improving SWD pest management strategies and therefore grower welfare and sustainability. Adeline is using her dynamic bioeconomic models to better understand how blueberry growers make their SWD pest management decisions; to design sustainable pest management strategies that maximize net benefits to society; and to inform evidence-based policy-making. The results of her research will be of interest to academics, policy-makers, agricultural producers, and business practitioners, alike.

For further reading:

  • Yeh, D. Adeline, Miguel I. Gómez, and C.-Y. Cynthia Lin Lawell.(2023). Sustainable pest management, beliefs, and behavior: A dynamic bioeconom ic analysis. Working paper, Cornell University.
    [Working paper]