Feeding conditions of the interspecific bumblebee association (Hymenoptera, Apidae, Bombus) in the central forest-steppe of the Omsk Region

This article reports that the main food plants of bumblebees of the interspecific association of the central forest-steppe of the Omsk Region during the period of flight activity (I decade of May – III decade of September) are 120 plant species from 30 families. Common and fairly common species predominate, which, under the condition of medium, high and superfroductivity, form the forage base. All rare, quite rare, very rare, as well as unproductive common and unproductive fairly common plant species perform a supporting function in the nutrition of bumblebees. At the beginning of the flight activity of bumblebees, low and medium-productive species predominate, then after the beginning of flowering of new species, highly and super-productive ones are included in the feed spectrum – there is a change in food conditions from unfavorable to favorable. During the main flight period, bumblebees feed or forage on 99 plant species, among which fairly ordinary medium-productive species predominate. Before the second decade of August, three peaks in the expansion of the food spectrum were revealed: in the third decade of May (by 15 species), in the second decade of June (by 31 species) and in the second decade of July (by 20 species). The exclusion of plants from the bumblebee diet occurs every decade. The greatest peaks were recorded in the II decade of July and in the III decade of August – by 21 species. Starting from the first decade of September, there is a change in food conditions from favorable to unfavorable. In general, the feed base of bumblebees of the interspecific association of the central forest-steppe of the Omsk Region has a stable character and allows to provide bumblebees with a sufficient volume of full-fledged feed.