Metapopulation Dynamics and Pest Control in Agricultural Systems

Abstract

In the first metapopulation model, R. Levins investigated the relative benefits of synchronous versus asynchronous application of control measures for agricultural insect pests. He concluded that synchronous control measures were optimal because synchrony removes temporary refuges for the pests. However, his conclusions rest on the assumption that there are no predators whose population dynamics are coupled to those of the pest. Using a novel metapopulation model, we investigate the consequences of synchronous versus asynchronous crop planting for the density of a pest either with or without specific predators. We show that whereas synchronous planting generally leads to the lowest pest densities in the absence of predators, in the presence of predators asynchronous planting may produce the lowest pest densities. The relative advantages of synchronous versus asynchronous planting depend on the population dynamics and migration rates of pests and predators within fields. Our metapopula- tion model is designed for application to real data, making it possible to select the optimal pest control strategy for particular crop systems. For many crops, such as rice grown in the Tropics, current guidelines promote synchronous planting. Our results show that asynchronous planting may potentially be better.