Bumblebees: Behaviour, Ecology, and Conservation
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Bumblebees are familiar and charismatic insects, occurring throughout much of the world. They are increasingly being used as a model organism for studying a wide range of ecological and behavioural concepts, such as social organization, optimal foraging theories, host-parasite interactions, and pollination. Recently they have become a focus for conservationists due to mounting evidence of range contractions and catastrophic extinctions with some species disappearing from entire continents (e.g. in North America). Only by improving our understanding of their ecology can we devise sensible plans to conserve them. The role of bumblebees as invasive species (e.g. Bombus terrestris in Japan) has also become topical with the growing trade in commercial bumblebee nests for tomato pollination leading to establishment of non-native bumblebees in a number of countries.
Since the publication of the first edition of the book, there have been hundreds of research papers published on bumblebees. There is clearly a continuing need for an affordable, well-illustrated, and appealing text that makes accessible all of the major advances in understanding of the behaviour and ecology of bumblebees that have been made in the last 30 years.
the thorax. During each pulse, little or no liquid ﬂows in the opposite direction, so the heat exchange system ceases to operate. At very low ambient temperatures, shunting heat from the thorax to the abdomen may serve a quite different purpose to avoidance of overheating. B. polaris is the northernmost social insect in the world, reproducing well within the Arctic circle. It is a large, unusually hairy bumblebee that is able to exist in regions where, even in the height of summer, ambient
has no measurable impact on the production of new queens. This does of course beg the question as to why the queen does not lay more diploid eggs, and so increase production of new queens? If the colony has sufﬁcient resources to rear worker-laid males, then it could presumably rear more future queens instead. Overall, Bourke and Ratnieks’ hypothesis ﬁts the available data reasonably well and is certainly the closest we have yet come to a full explanation for the reproductive strategies adopted
small ones, since this would minimize travelling time between ﬂowers. However, if all bees adopted this strategy, then large patches would become overrun with bees, and ﬂowers in small patches would contain much more nectar because they would never be visited. Whatever size of patch a bee chooses, it must then decide how long to stay. The longer it stays in a patch, the more depleted the resources will become, unless the patch is so large that it produces rewards faster than the bee can gather
insects that do visit them, so perhaps they can afford to provide higher quality pollen to reward their visitors and further promote ﬁdelity. This page intentionally left blank 9 Intraspeciﬁc Floral Choices Within plant species, individual ﬂowers exhibit considerable variation in the rate at which they produce rewards. There can also be substantial variation between ﬂowers on the same plant. This variation may be due to micro-environmental inﬂuences, genetic variation, age of the plant or age
carried out by hand using a vibrating wand, no doubt a very tedious job and costly in terms of labour (Cribb 1990). Honeybees have been used for tomato pollination but they provide an erratic yield, and from preference will not visit tomato ﬂowers (Spangler and Moffett 1977; Banda and Paxton 1991). In contrast, bumblebees are highly effective pollinators, and give increased yield compared to honeybees or hand pollination (Banda and Paxton 1991). Some even claim that bumblebee-pollinated fruit