Abstracts (first author)
Thermal changes alter the outcome of behavioural interactions between co-evolved host-parasitoid species
Climate change often triggers the question if species response to a changing environment will enable them to persist. However, species and especially tightly co-evolved ones, do not exist alone and are largely dependent on interactions with others within communities. Here, we use a mechanistic approach to test the general hypothesis that interspecific differences in the response to short-term thermal changes can change the outcome of host-parasitoid behavioural interactions. We measured the effect of temperature (15, 20 and 25°C) on resting metabolic rates (RMR) of the main pest of cereal crops in Western Europe, the grain aphid host pest Sitobion avenae and its main specialist parasitic wasp, Aphidius rhopalosiphi. Also, thermal behavioural responses of host and parasitoid were measured independently and in interaction, since behavioural strategies of both species largely determine parasitism success. At high temperature parasitoids had lower oviposition efficiency and aphids expressed more defensive behaviours. This alteration in behaviour is likely due to the higher RMR of hosts than parasitoids at high temperature, suggesting RMR is a valuable proxy for predicting the direction of change in the outcome of species interactions. We proposed temperature-induced alteration of species interactions to be a mechanism through which climate change affects ecological communities. Since our findings show that relatively modest thermal changes with non-lethal effects can alter interactions in co-evolved species, ecosystem services such as biological control of pest populations, could be drastically affected.