[Comparison of imaginal diets of various Syrphidae (Diptera) species]

The full amount and species composition of pollen from intestines of 11 species of Syrphidae (Arctophila fulva, Eristalis arbustorum, E. nemorum, E. pertinax, Helophilus pendulus, Myiatropa florea, Rhingia campestris, Sericomyia silentis, Syrphus baltheatus, S. ribessii and S. vitripennis), collected at the some place (Torma, Jogeva distr., Estonia) and at the some time (18-20 July 1989) have been studied. Maximum number of pollen grains is different fly species varied from 67,800 (Rh. campestris) up to 240,700 (S. silentis) grains, and average number from 25,560 (Rh. campestris) up to 115,880 (E. pertinax) grains. Maximum volume of pollen in different fly species varied from 1.5 (S. ribesii) up to 23.6 (S. baltheatus) mm3, and average volume from 0.36 up to 7.0 mm3 (the same species). The difference in a imaginal diets of Syrphidae are found, and the degree of difference does not correlate with a degree taxonomic affinity of species. The difference in strategy of a feeding behavior of two Syrphus species, that have similar diet, are marked: in intestines of 80% specimens of S. ribesii we found pollen grains of less that 7 plant species, whereas intestines of more than 88% specimens of S. vitripennis contained more than 8 species of grains. Distinction in alimentary preferences of different species of files can not be explained neither particularities of their morphology, nor their color preferences.