Mechanism of density compensation in island bumblebee assemblages (Hymenoptera, Apidae, Bombus) and the notion of reserve compensatory species

Abstract

The notion of a dynamic compensatory system is discussed, characterized by the alternation of species occupying the leading position in bumblebee assemblages, while the total density of these pollinators in island ecosystems remains at similar levels. The functioning of the compensatory system is regulated by both abiotic factors (the weather and climate) and biotic factors (competition for trophic resources). The sta bility of the system is determined by the presence of reserve compensatory species capable of rapid population growth against the background of depressed abundance of other species under changing environmental con ditions.

Review of the Icelandic bee fauna (Hymenoptera: Apoidea: Anthophila)

“…Cultivated areas are avoided (LØKEN 1973 in weather and climate conditions. The superdominance of B. jonellus was positively correlated with a high frequency of winter-thaws and negatively correlated with summer heat supply (BOLOTOV et al 2013). Thaws from January to March were unfavourable for bumblebees and resulted in high mortality rates.…”

“…In contrast to B. terrestris the colonies are not so rich in individuals and the diapause is longer, therefore this species is not domesticable. BOLOTOV et al (2013) has shown that in contrast to B. jonellus, in the course of overwintering the abundance of B. lucorum is negatively influenced by thaws from October to January and positively correlated with the thickness of the snow cover and with dry weather conditions in summer. The snow cover is largest in northern and northeastern Iceland during December and through March (EINARSSON 1984).…”

“…The nests are generally established aboveground in tree hollows, abandoned swallow nests, bird boxes in trees, or house walls (LØKEN 1973). BOLOTOV et al (2013) has shown that in the course of overwintering the abundance is negatively influenced by thaws from January to March.…”

“…High population densities in B. jonellus are present in cold summer seasons (BOLOTOV et al 2013). B. jonellus colonises successfully the Subarctic (forest tundra, hypoarctic tundra) with nesting preferences along sea coast and in river deltas within the drier conditions of well-drained sandy soils (BOLOTOV et al 2013). …”

Possible bivoltine development of several bumblebee species in Europe

“…Bumblebees from European North of Russia were studied on the Solovetsky Archipelago during longterm research 2001-2010(Kolosova and Podbolotskaya 2010, Bolotov et al 2013. 119 individuals were studied for the present research.…”