Insect-plant relationships form another important item on my research agenda.
My model system is the Allium ursinum food web with
Allium ursinum - Cheilosia fasciata - Phygadeuon ursini
as its core food chain.
Cheilosia fasciata is a larval leaf miner and Phygadeuon ursini is its pupal parasitoid.
This is a species-poor system and I have sketched a portrait of the web including other parasitoids, predators, and food plants of adults (Hövemeyer 1995). A german version of this has been included in Kratochwil & Schwabe (2001).

I am interested in the strategies employed by all Allium-feeders but my research has largely concentrated on the hoverfly Cheilosia fasciata, which is by far the most abundant herbivore species (For an illustrated life cycle of C. fasciata click here).

I have studied many aspects of the ecology of Cheilosia fasciata. For example, correlation analyses, key factor analysis, and experimental studies showed that the population dynamics of this species are almost equally strongly influenced by

(i) weather conditions during the oviposition period,
(ii) competition for food among older larvae,
(iii) parasitization of pupae.

Further studies considered diurnal activity patterns of adult Cheilosia fasciata, oviposition behaviour of females (Hövemeyer 1995, 1996), nutrient and energy flow in the plant-herbivore-parasitoid food chain (Hövemeyer 1995). For example, females lay only one egg per leaf (first observed by Nielsen 1979), and this habit can serve to reduce competition among larvae (Hövemeyer 1987).