The Ecology of Critical Transitions in Pest Control in The Coffee Agroecosystem

Regents Of The University Of Michigan - Ann Arbor, Ann Arbor MI

Investigators

Abstract

The inevitability of surprise is a characteristic of ecological systems. While most sciences are founded on a regular set of laws or principles such that a particular input results in a predictable and consistent output, one of the key ideas of ecological systems is that this inherent predictability is frequently violated, mainly because of the complex interconnections they contain. Thus, while physics and astronomy, for example, rightly celebrate their ability to make precise predictions about what happens at extremely large (e.g., the universe) and extremely small (e.g., atoms) levels, ecological systems are known for their inherent unpredictability, one aspect of which is sudden, drastic, and at times unexpected change. Such events are frequently referred to as a "critical transition." An evident example is the sudden outbreak of pests in agricultural systems. This project seeks to understand the structure of these unexpected changes in the pest systems that have generally plagued food production since times immemorial and that currently threaten one of society's favorite beverages. This project uses the coffee agroecosystem as a model ecosystem, to ask how classical ideas of critical transitions (in this case, sudden pest outbreaks) reflect theoretical constructs that emerge from basic ecological theory. Pest outbreaks in managed systems are potentially driven by critical transition phenomena; rather than a slowly accumulating increase in pest problems in response to management decisions, frequently they seem to suddenly jump from one relatively stable system (low pest population) to another one (high pest population). In addition, managers seeking to reverse this process, may face the related problem of hysteresis: the sudden pest outbreak when a management threshold is reached does not reverse itself in the same way when that threshold reverts to its previous level. The three major pests on the coffee farms of southern Mexico are all connected in subsystems that have theoretical structures (modules), each of which suggests conditions under which critical transitions will occur. The research seeks to determine whether these three well-defined modules (subsystems) demonstrate critical transition behavior. Furthermore, the work aims to understand implications at a larger scale when these three subcomponents, each of which separately can be expected to show critical transition behavior, are coupled as they obviously are in reality. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.