Thrips biological control agent shows greater niche overlap with invasive alligatorweed than conventional agent in current and future climate scenarios

Alternanthera philoxeroides (Mart.) Griseb. (Amaranthaceae: Caryophyllales) is an aquatic invasive weed from South America with a long history of biological control. The well-studied Agasicles hygrophila Selman & Vogt, 1971 (Coleoptera: Chrysomelidae) successfully controls A. philoxeroides in some parts of its invaded range, but is unsuitable in other areas due to its intolerance to cold temperatures. Amynothrips andersoni O’Neill, 1968 (Thysanoptera: Phlaeothripidae) has shown greater tolerance to cold temperatures, but no research has been conducted to determine its ecological niche with respect to A. philoxeroides. The aim of this study is to predict the environmental niches of A. andersoni and A. hygrophila and their overlap with that of A. philoxeroides in the North and South America under current and future climate scenarios. Accordingly, niche models were constructed in MaxEnt for all three species using environmental variables from the current climate and under two future climate scenarios (SSP1-2.6 and SSP5-8.5) for the year 2040. The niche overlap between the two biological control agents and the host were estimated for all three scenarios. Under both future climate scenarios, the total niche of A. philoxeroides is predicted to decrease by up to 10% whereas niche area is expected to increase by up to 10% for A. andersoni and A. hygrophila. Amynothrips andersoni had a greater niche overlap with A. philoxeroides than did A. hygrophila under all three scenarios, suggesting it is currently more widely suitable for A. philoxeroides biological control and should continue to be in 2040.