Predicting biological control performance under global change using model-based exploration of predator-prey dynamics: application to the Nesidiocoris tenuis - Tuta absoluta system

Abstract

Global change is disrupting our knowledge of ecosystem functioning through climate warming and pest invasion, affecting predator-prey population dynamics. We hypothesized that the control of invasive pests by native predators would decrease with increasing temperatures. We investigated the effects of high temperatures jointly with other factors related to biological control conditions (i.e., habitat complexity reflected by predator searching efficiency, predator-to-prey ratio, and relative timing of species establishment) on predator-prey population dynamics for the zoophytophagous and generalist mirid bug, Nesidiocoris tenuis, and the tomato leaf miner, Tuta absoluta, a native insect predator and an invasive insect pest, respectively, in Senegal. We carried out life history trait measurements in the laboratory at different temperatures (i.e., constant temperatures of 25, 30, 35, 40, and 45 °C and temperatures of 40:35 °C alternating following the light and dark cycle). We developed a stochastic individual-based model to simulate predator and prey population dynamics. Both species were able to complete their life cycle until 35 °C and until 40 °C when the night temperature decreased to 35 °C, while populations persisted over time only at 25 and 30 °C. Contrary to our expectations, pest control increased with temperature due to a higher predation efficiency and asymmetries between insect fitness responses to temperature in favor of the predator. Our study showed that populations of T. absoluta would not increase at high temperatures, either due to successful control by N. tenuis at 30 °C or due to a population collapse at 35 °C and beyond, as T. absoluta approaches its critical thermal maximum. At a temperature less favorable for pest control (25 °C), the timing of predator and pest establishment was the main factor determining the performance of pest control. Control was ensured when the predator established before or close to pest infestation. This can occur with generalist predators that can survive by feeding on alternative resources.