Succession of communities of Diptera larvae in decaying fungi

The effect of season on a community of dipteran larvae decomposing decaying fungi was studied. Dried and rewetted mushrooms were placed in litter-bags and exposed to the floor of a mixed forest near Moscow in four different s easonal aspects: spring, early and late summer and autumn. In total 25 morp hospecies of dipteran larvae were found. No exclusive fungivorous species w ere revealed among the dominants, while saprophagous species with some affi nity to decaying fungi prevailed. In all cases a higher larval abundance wa s found soon after the start of exposure and decreased later. The season of exposure affects larval the community in two different ways: due to tempor al coincidence with the colonizers' occurrence and due to food quality. The food quality of autumnal treatment differs substantially from the others. Overwintering of fungi under snow, results in leaching of some nutrients, a slower rate of decomposition and lower abundance of dipteran larvae. The o ccurrence of the most numerous species (Trichocera sp., Psychoda spp.) was highly seasonal with the exception of Metriocnemus atratulus. Hence the tim e of exposure and stage of decay are considered as the main factors affecti ng the species composition of the dipteran community.