Warming Reduces Parasitoid Success and Narrows Their Diet Breadth

A significant area of current research is the impact of warming on trophic networks. However, few interactions per network are typically studied, which limits generalisation and precludes evaluation of impact on consumer diet breadth and redundancy of top-down control. Here we show that experimental warming strongly decreased the success of parasitoid development across 28 Drosophila-parasitoid interactions from a tropical rainforest network. Parasitoids responded consistently despite deep evolutionary divergence. Moreover, warming strongly narrowed the diversity of hosts that the parasitoids could use. Host developmental success was much less affected. In contrast, experimental cooling had only a mild effect on parasitoids and hosts. Our findings suggest that the top-down control exerted by parasitoids is likely to weaken due to warming. The range of hosts that parasitoids can use will become more limited, potentially threatening the sustainability of parasitoid populations and changing the balance between trophic levels.