Riikka Kaartinen

I finished my PhD  in April 2011 with Tomas Roslin  as my supervisor (For thesis intro, see https://helda.helsinki.fi/handle/10138/24932). My thesis examined how the composition of surrounding landscape affects the structure of food webs, and how consistent these food webs are temporally. I continued to work with Tomas as a post doc after finishing my thesis.

I am interested in insect community ecology, host-parasitoid interactions, food webs and ecosystem function. What happens to species and interactions at different trophic levels when surrounding habitat changes, new species colonize the community, or some species go extinct? Excellent model systems for food web studies are herbivorous insects and their parasitoids wasps. Before my PhD I have worked also with parasitoid behavioural ecology and taxonomy.

In my PhD I examined how food web structure is affected by the configuration of surrounding landscape. I also measured how temporally consistent these webs are.  As one key part of my thesis, I used DNA barcoding to resolve cryptic species in the food web, and examined their effect on food web structure. As a model system, I used a community of nearly 90 species of specialized herbivorous insects on oak and their natural enemies. These species included gall wasps, leafminers and their parasitoid and inquiline wasps. I constructed 30 quantitative food webs in a spatially explicit setting, at two different scales.

Currently in my post doc I work with two projects. One untangles the relationship between ecosystem function and diversity, measured at the level of species and functional groups. As the measure of function I use the decomposition of dung by dung beetles and earth worms. This question was examined by a nation-wide experiment, taking advantage of citizen science. The second project is a long-term initiative where first fully quantitative food webs are built for an arctic site, using arthropod community in Greenland as a model system. Here we utilize DNA barcoding to resolve species and interactions in the community.