The impacts of predators and parasites on wild bumblebee colonies

Abstract

1. The study of wild bumblebee nests has been hindered by the difficulty in locating and observing them. Here, wild nests were located using a sniffer dog and volunteers. The entrances to 32 nests were filmed continuously to identify successful nests (those which produced gynes) and observe vertebrate species interactions. 2. Of the 47 nests, 71% and 21% produced gynes in 2010 and 2011, respectively. 3. A total of 39 vertebrate species were filmed at entrances but the majority did not interact with the nests. Great tits (Parus major) depredated or attempted to depredate bees on 32 occasions at the entrances to ten nests, something which has not previously been described. Small mammals were very often recorded accessing entrances to bumblebee nests, but whether they depredated bees was not known, and frequentlyvisited nests were no less likely to produce gynes. Eight nests were entered by adult wax moths, Aphomia sociella. 4. The faeces of 1,179 workers from 29 Bombus terrestris nests were screened microscopically for parasites. Crithidia bombi infections were apparent in 49% of worker bees, while Nosema bombi and Apicystis bombi were present in 5.5% and 0.68% of bees, respectively. Nests with a high prevalence of C. bombi infection were less likely to produce gynes, the first evidence for a direct impact of this common parasite on bumblebee colony reproduction in wild nests. 5. Overall, our data indicate that bumblebee nests are at the heart of a rich web of interactions between many different predator and parasite species.

Disease where you dine: plant species and floral traits associated with pathogen transmission in bumble bees

“…, Goulson et al. ). This pathogen is transmitted when feces from an infected individual are consumed by an uninfected bee (Durrer and Schmid‐Hempel ).…”

Effect of timing and exposure of sunflower pollen on a common gut pathogen of bumble bees

“…Crithidia bombi [Kinetoplastea, Trypanosomatida] is a common pathogen of multiple bumble bee species (Gillespie, 2010) that can be contracted at flowers and transferred among nest mates via faecal-oral transmission (Durrer & Schmid-Hempel, 1994). Wild B. terrestris colonies infected with C. bombi are less likely to produce new daughter queens compared with uninfected colonies (Goulson et al, 2017). Crithidia infection reduced queen colony founding success and colony size (Brown et al, 2003), and reduced motor learning rates of flower handling in B. impatiens (Gegear et al, 2005), which could influence how effectively bumble bees pollinate and forage (Koch et al, 2017).…”

Quantifying the relative predation pressure on bumblebee nests by the European badger (Meles meles) using artificial nests

“…Resource availability can differ between habitats (Baude et al, ) and can be impacted by human activity that results in habitat loss and fragmentation (Goulson, Nicholls, Botías, & Rotheray, ; Potts et al, ). In contrast, top‐down regulation refers to factors that cause mortality: these can be human‐induced, for example, as a result of pesticide use (Gill, Ramos‐Rodriguez, & Raine, ; Rundlöf et al, ), or they can be natural, for example, disease (Manley, Boots, & Wilfert, ) or predation (Goulson, O'Connor, & Park, , ). Top‐down effects which cause direct mortality act alongside bottom‐up regulatory effects to influence the stability of bumblebee populations.…”

“…The degree to which predation of bumblebee nests has an impact on bumblebee populations is relatively unknown. In Europe, nest predators include birds, such as great tits (Parsus major), which predate workers entering and exiting the nest (Goulson, O'Connor, & Park, 2018b), and wax moths (Aphomia sociella), which infest colonies and destroy most of the comb (Alford, 1975;Goulson, Hughes, Derwent, & Stout, 2002;Pouvreau, 1973;Sladen, 1912). There is little evidence that either of these two nest predators have negative impacts on colonies in terms of gyne production (Goulson, O'Connor, & Park, 2018a;Goulson et al, 2018b).…”