COEVOLCLIM

How temperature affects co-evolutionary interactions between partners: a study on physiological underlying mechanisms

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 Obiettivo del progetto (Objective)

'Global warming often triggers the question if species response to a changing environment will enable them to persist. However species persistence is also dependent on species interactions. Relationships between tightly co-evolved species within communities are expected to be disrupted by thermal changes. An example of a co-evolutionary arms race is found in parasitoid insects, which develop in other arthropods to complete their larval development. The outcome of host-parasitoid interactions is known to depend on thermal regime but a full understanding of the effect of temperature requires insight into the underlying mechanisms. The proposed research will elucidate the effect of temperature on the interactions between the grain aphid host Sitobion avenae and its main specialist parasitoid, Aphidius rhopalosiphi. I will examine the thermal responses of the outcome of aphid parasitoid interactions in the pre-oviposition phase, when behavioural strategies largely determine parasitoid oviposition success, and in the post-oviposition phase, when the parasitoid is developing inside the aphid, as immunological interactions determine aphid or parasitoid survival. Most importantly, I will identify the underlying physiological mechanisms of behavioural and immunological responses that determine the outcome of the interaction. The combination of mechanistic and ecological approaches will provide understanding of the impact of temperature on interacting species that can be extrapolated to other systems.'

Introduzione (Teaser)

Will global warming affect species survival? Research has to look at the added effect of species interactions to answer the question.

Descrizione progetto (Article)

Many species are dependent on temperature for other ecological niches, such as the reproductive or food niche, for example. Relationships between tightly co-evolved species may also be affected by thermal change.

Parasitism is perhaps the archetypal example of a co-evolved relationship. To investigate the effects of temperature change, the EU-funded COEVOLCLIM project looked at the grain aphid, Sitobion avenae and its main parasitoid, Aphidus rhopalosiphi. The aphid pests feed on winter and spring cereals and the parasitoid wasp lays its eggs in the aphid where they develop.

COEVOLCLIM researchers looked at the effects of temperature at the pre-egg laying stage when behavioural effects come into play. At the post-egg deposition phase, immunological interactions affect survival of both when the parasitoid is developing in the aphid.

Both behavioural and immunological interactions were disrupted by temperature but warmer temperatures had a stronger effect on these interactions. At warmer temperatures, physiological responses such as metabolic rate and behavioural parasitoid attack rate affect the relationship. At lower temperatures, there is a reduction in activity of both species. For immune interactions, aphid resistance increased with temperature.

The research has given an insight on the possible effects of climate change on host-parasitoid relationships that can be applied to other species. In particular, this would apply to ectotherms such as insects, snakes, turtles, snails whose body temperature relies primarily on the ambient temperature.

In a time of great change and where conservation is paramount, knowledge about the effects of climate change on plant and animal communities is crucial. Bio-control methods can also use information on species temperature relationships to improve pest regulation for hothouse crops.