Drastic shifts in the Belgian bumblebee community over the last century

Abstract

Bumblebees are undergoing strong declines in Europe caused by habitat loss and fragmentation, agricultural intensification, and climate change. Long-term records are necessary to estimate population trends precisely and to propose appropriate mitigation strategies. Based on an original database of 173,788 specimens from museum collections, scientific monitoring, and opportunistic citizen data from 1810 to 2016, we compared changes in species richness and area of occupancy of Belgian bumblebee species through three time-periods (1910-1930, 1970-1989, and 1990-2016). We also assessed if the observed trends are related to species-specific ecological traits and spatial scales (local, regional and national). Overall, species richness decreased over the last century in Belgium, but some regions retained relatively species-rich communities.A strong shift in community composition occurred. Three species remained among the "top five" in terms of species occurrence (area of occupancy) between the three timeperiods (B. pascuorum, B. lapidarius, and B. pratorum), but several species that were once widespread declined drastically (B. muscorum, B. humilis, B. ruderatus, and B. veteranus), while a few species increased their distribution (e.g. B. hypnorum and B. terrestris). Habitat preferences significantly explained the observed trends, with declining species preferring open habitats and increasing species preferring wooded habitats.

No severe genetic bottleneck in a rapidly range-expanding bumblebee pollinator

“…Hence, colonization of the UK by B. hypnorum does not represent an example of the genetic paradox of invasion [5,38] or an example of a eusocial Hymenopteran achieving rapid range expansion despite high levels of DMP [19,20]. Alongside evidence of B. hypnorum undergoing a recent westward range expansion within Europe [35,45,46], our findings suggest that this species may resemble other invertebrate taxa that have recently expanded their ranges at a continental scale. Examples in Europe include the wasp spider (Argiope bruennichi) [60] and the dainty damselfly (Coenagrion scitulum) [61].…”

“…Given that B. hypnorum is rapidly expanding its range across the UK, and possibly recently did so across north-western Europe [ 35 , 45 , 46 ], one might expect some loss of genetic diversity to occur, since the leading edge of a dispersal front is subject to a loss of alleles and heterozygosity as it moves further from the source population [ 56 ]. This is especially true under leptokurtic dispersal [ 56 ], where small numbers of long-distance dispersers found new sub-populations, as appears likely to be the case for B. hypnorum queens in the UK [ 48 ].…”

“…Recently, up to 11 alleles were found at neutral microsatellite loci in workers of a UK B. hypnorum population, in which queen mating frequency was estimated at 1.7 mates per queen [ 37 ], suggesting a founding population of greater than two queens. Moreover, recording data show that B. hypnorum has expanded its range westwards within continental Europe across Germany and Belgium from the middle of the twentieth century [ 35 , 45 , 46 ], suggesting that colonization of the UK may represent part of an ongoing, large-scale range expansion in Europe. Hence, whether colonization of the UK by B. hypnorum truly exemplifies the genetic paradox of invasion is uncertain.…”

“…[29][30][31]). However, at regional scales, some bee species are expanding their ranges, through either human transportation or natural colonization events [26,[32][33][34][35]. Given concerns over maintaining bee populations, there is special interest in determining the relationship between ecological success and the genetic consequences of bottlenecks, mediated by sl-CSD, in range-expanding eusocial bee species [24,26].…”

Contribution to the knowledge of the bumblebee fauna of Afghanistan (Hymenoptera, Apidae, Bombus Latreille)

“…These large colorful bees, represented by ~ 260 described species worldwide (Williams et al 1998), form an increasingly popular model group for large-scale studies in the fields of biogeography (Williams et al 2017), population genetics (Ghisbain et al 2020), evolutionary biology (Tian et al 2019) and more worryingly, global change biology (Kerr et al 2015;Rasmont et al 2015). Bumblebee populations are indeed undergoing serious regressions worldwide, mostly attributable to anthropogenic disturbance such as habitat destruction or climate change (Williams and Osborne 2009;Cameron et al 2011;Cameron and Sadd 2020;Rollin et al 2020).…”