Abstract
It is unclear how sustained increases in temperature and changes in precipitation, as a result of climate change, will affect crops and their interactions with agricultural weeds, insect pests and predators, due to the difficulties in quantifying changes in such complex relationships. We simulated the combined effects of increasing temperature (by an average of 1.4°C over a growing season) and applying additional rainwater (10% of the monthly mean added weekly, 40% total) using a replicated, randomized block experiment within a wheat crop. We examined how this affected the structure of 24 quantitative replicate plant-aphid-parasitoid networks constructed using DNA-based methods. Simulated climate warming affected species richness, significantly altered consumer-resource asymmetries and reduced network complexity. Increased temperature induced an aphid outbreak, but the parasitism rates of aphids by parasitoid wasps remained unchanged. It also drove changes in the crop, altering in particular the phenology of the wheat as well as its quality (i.e., fewer, lighter seeds). We discuss the importance of considering the wider impacts of climate change on interacting species across trophic levels in agroecosystems.
Highlights
Climate change is expected to have profound impacts on food production systems over the coming decades (Lobell et al 2008)
Primary and secondary parasitoids were considered as belonging to the same trophic level and separate primary parasitoid – secondary parasitoid interactions were not examined (Figure 1)
The 1946 aphids included in the ecological network analysis represented 56.3% of the total aphids counted in the experimental plots
Summary
Climate change is expected to have profound impacts on food production systems over the coming decades (Lobell et al 2008). Despite the growing research demonstrating the impacts of climate change on species abundances and distributions, community composition and organismal physiology (Sala et al 2000; Parmesan 2006; Garcia et al 2014), climate change effects on the networks of interactions among species are poorly understood (Tylianakis et al, 2008), in agro-ecosystems. This is largely due to the difficulties in quantifying changes in interactions compared with changes in biodiversity (McCann 2007). Species-interactions may, be more susceptible to climate change, as they are sensitive to the phenology, behaviour, physiology and relative abundances of multiple species (Memmott et al 2007; Suttle et al 2007; Tylianakis et al.2007)
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