Thermal niche partitioning following successive invasions by potato moths in the Northern Andes

The movement of organisms beyond their natural range is a major threat to the sustainable provision of ecosystem products and services, both in natural and agricultural ecosystems. We examined the tolerance to temperature and analyzed the field distribution of three potato tuber moths (Lepidoptera: Gelechiidae) in Ecuador, that successively invaded northern Andean agricultural areas, in order to evaluate the opportunities of species coexistence by niche differentiation. We developed simulation models for the three pest species to predict the phenology, developmental and survival rates of the various stages and overall population dynamics. The models used the state-variable approach, and included only temperature as a driving variable. The three species differed with respect to their thermal optima. While Phthorimaea operculella is sensitive to temperatures lower than 16°C, Tecia solanivora and especially Symmetrischemma tangolias are more resistant to low temperatures. Overall, field distributions agreed with the predictions based on our models and suggest that thermal niche partitioning promotes coexistence between some pairs of invasive species. By promoting (or not) coexistence, the climatic diversity in agricultural areas (such as temperature gradients provided by high mountains) can directly affect the community composition following invasions. These results may have important implications for the conservation of biodiversity in agricultural landscapes. The fast upward expansion of the agricultural frontier to higher natural areas such as "paramos", provides potential food resources and ecological niches to new invasive pests with uncertain consequences for both native plant and insect communities.