The decline of the bumble bees and cuckoo bees (Hymenoptera: Apidae: Bombini) of Western and Central Europe

Abstract

The bumble and cuckooo bees (Hymenoptera: Apidae: Bombini; Bombus spp. and Psithyrus spp., respectively) are important plant pollinators and any decline in numbers or species constitutes a significant threat both to biological diversity and to whole economies. The distribution, status and factors threatening all 60 known taxa (species and subspecies) of Bombini of 11 countries of Western and Central Europe (Belgium, the Netherlands, Luxembourg, Denmark, Germany, Switzerland, Austria, Czech Republic, Slovakia, Hungary, Poland) were assessed from the beginning of the 20th century. The analysis was based on a literature review, unpublished data, personal communications, our own observations, and an expert review. The IUCN Red List categories were used for assessing the threat of extinction. Eighty per cent of taxa were threatened in at least one country of the region, and 30% of taxa were threatened throughout their range in the countries considered. More species went extinct per country in the second than in the first half of the 20th century, and four taxa went extinct in all 11 countries during 1951–2000. Amongst the factors adversely affecting the Bombini anthropogenic factors (particularly those associated with large-scale farming schemes) appear to be of greater importance than natural factors. To halt population declines and species extinctions it will be necessary to preserve aspects of traditional farming practices and for all Bombini to be afforded legal protection in all countries of the region. The implementation of the European Union's Common Agricultural Policy is likely to have the greatest single impact upon pollinators in the near future.

The most effective pollinator revisited: pollen dynamics in a spring-flowering herb

“…Our results show that bumblebees are the most effective pollinators of F. meleagris, when both quality and quantity component of pollination is concerned; furthermore, they visit flowers (and therefore pollinate) even in bad weather conditions (Hedström 1983;Zych and Stpiczyńska 2012). Although these insects are generally declining in Central Europe (Kosior et al 2007;Goulson et al 2008a), the taxa present in our study belong to common species and the plant can be successfully pollinated also by other floral visitors, which suggests that its pollination biology cannot alone explain its rarity.…”

Bombus cullumanus—an extinct European bumblebee species?

“…Individuals with the dark female colour pattern, B. cullumanus cullumanus s. str., are known to be in strong decline in Britain (Yarrow 1954;Alford 1975), in France (Rasmont 1988;Rasmont et al 2005a), and in Western Europe generally (Kosior et al 2007). A remnant population with this colour pattern was known in the French Pyrenees (Iserbyt et al 2008) at least as recently as 2001, but the very last live individual with this colour pattern to be seen was in the Massif Central of France in 2004.…”

“…A remnant population with this colour pattern was known in the French Pyrenees (Iserbyt et al 2008) at least as recently as 2001, but the very last live individual with this colour pattern to be seen was in the Massif Central of France in 2004. The light yellow female colour pattern, B. cullumanus serrisquama, is in decline in Hungary (Sárospataki et al 2005) and in Western Europe generally (Kosior et al 2007), where it is now very rare. However, in the steppes of the west Siberian plain, it is still the dominant or subdominant species of bumblebee (≥10 % of the total number of bumblebees) in 13 of the 36 localities sampled by one of us (Table III).…”

Low functional diversity promotes niche changes in natural island pollinator communities

“…In recent decades, pollinators with a long proboscis (longtongued pollinators) such as bumblebees and butterflies have declined drastically worldwide [25][26][27][28][29][30], likely resulting in a functional diversity loss in the pollinator guild. Owing to the usually intimate associations between long-tongued pollinators and flowers with specialized floral organs, such as long corolla tube and spur ( [31,32]; figure 1), declines in long-tongued pollinators can lead to such plants becoming pollinator-limited [16,19,20,33].…”