The effect of food supplementation on reproductive success in bumblebee field colonies

Abstract

2003. The effect of food supplementation on reproductive success in bumblebee field colonies. -Oikos 103: 688-694.Food availability is a major component of habitat quality. For bumblebee field colonies, it is unknown to what extent reproductive success is limited by food availability relative to other factors such as parasites. To assess the importance of food availability, we carried out a field experiment in the Quebec City area, Canada, in 1999 and 2000, using 45 colonies of Bombus impatiens and B. ternarius. Colonies whose nectar and pollen supplies were increased regularly throughout the season reached larger sizes (in number of workers) and had a higher reproductive success than controls, by 51% and 86% respectively. In particular, food supplementation increased the number of males produced and the probability of producing gynes (young queens). The sex ratio was highly skewed in favour of males overall, and the relative proportion of gynes increased with food supplementation in B. ternarius, but not in B. impatiens. These results suggest that colonies ensure reproduction by producing some males and, given the opportunity (sufficient food availability), will produce gynes. Possible reasons for the increased success of food supplemented colonies are explored. However, despite some clear advantages of having larger food supplies such as the build-up of larger worker populations, food supplementation did not appear to help colonies defend themselves against macroparasites because experimental and control colonies experienced similar levels of parasitism by Psithyrus, Fannia canicularis, Brachicoma de6ia and Vitula edmandsae.

Pollen and nectar quality drive the major and minor floral choices of bumble bees

“…Our results further highlighted the dependence of polylectic bumble bee species on multiple floral resources for pollen, which has been experimentally shown to positively influence larval development in raised colonies of B. terrestris (Génissel et al 2002;Pelletier and McNeil 2003;Tasei and Aupinel 2008). However, diet breadth associated with chemical components was not similar among the four bumble bee species.…”

Nectar discovery speeds and multimodal displays: assessing nectar search times in bees with radiating and non-radiating guides

“…1a), have been shown to increase the attractiveness of flowers over others which do not have them (Manning 1956;Free 1970;Dinkel and Lunau 2001;Leonard and Papaj 2011;Leonard et al 2013). Considering the potential benefits to nectar discovery times and accuracy, these preferences are unsurprising given that even small increases in the rate at which nectar is collected can scale up to increase the reproductive success of the entire colony (Pelletier and McNeil 2003). Bees have also been shown to visit artificial flowers with visual nectar guides when the flowers no longer offered a reward, but did not do so for plain flowers, highlighting the benefit of nectar guides to plants which can receive visits regardless of reward status (Leonard and Papaj 2011).…”

The correlation of learning speed and natural foraging success in bumble-bees

“…In bumble-bees, the amount of food brought into the colony has a very strong influence on the output of sexually active offspring (males and new queens: Pelletier & McNeil 2003;Ings et al 2006), thus tightly linking colony foraging performance and reproductive output. As such, foraging performance represents a robust proxy measure of fitness.…”