Hold'em or fold'em: Nonlinear effects of pest retention on trap cropping efficacy

Trap cropping can be an effective and sustainable strategy for pest control in agricultural systems. While simulation models have been used to determine the characteristics of insects and plants important for maximizing the efficacy of trap cropping, the models often feature so many details that it is difficult to tease apart complex relationships and provide general conclusions. Therefore, it is necessary to analyze simpler models of insect movement to better understand the detailed functional relationship between key parameters and pest density in trap cropping systems. To do this we developed a simulation model that focuses on plant attractiveness and plant retention of insects. The results from this model show that the relationship between these parameters and pest density can be be drastically nonlinear. Perhaps the most nonintuitive of these nonlinearities is the relationship between trap crop retention and cash crop pest density. When trap crop retention is high, small changes in retention can cause large changes in cash crop pest density. If retention is low, changes in retention have almost no effect on the proportion of insects on the cash crop. The implications of this result for the use of trap cropping in pest management will be discussed.