An evaluation of (Z)-9-tricosene and food odours for attracting house flies, Musca domestica, to baited targets in deep-pit poultry units

Field trials investigating the effect of food baits on catches of Musca domestica at toxic targets impregnated with the female sex pheromone, (Z)-9-tricosene, were conducted in a caged-layer deep-pit poultry unit in southern England. Targets treated with an Alfacron-sugar mixture and baited with 2.5 g of 40% (Z)-9-tricosene beads caught significantly greater numbers of both male and female M. domestica than control targets. Egg and milk-baited targets were less attractive than controls, while brewers yeast slightly increased the numbers of M. domestica attracted. However, the inclusion of brewers yeast in (Z)-9-tricosene-impregnated targets produced a significant reduction in the number of male M. domestica attracted. Increased female attraction was elicited by baiting the targets with 2-phenylethanol, at the quantities of 1 mg and 10 mg. However, 2-phenylethanol had no effect on female attraction when presented in conjunction with (Z)-9-tricosene. The implications of these results in relation to the control of M. domestica populations in poultry units are discussed.     

Diet characterisation of solitary bees on farmland: dietary specialisation predicts rarity

Changes in agricultural practice across Europe and North America have been associated with declines in wild bee populations. Bee diet breadth has been associated with sensitivity to agricultural intensification, but much of this analysis has been conducted at the categorical level of generalist or specialist, and it is not clear to what extent the level of generalisation within generalist species is also associated with species persistence. We used pollen load analysis to quantify the pollen diets of wild solitary bees on 19 farms across southern England, UK. A total of 72 species of solitary bees were recorded, but only 31 species were abundant enough to allow for formal diet characterisation. The results broadly conformed to existing literature with the majority of species polylectic and collecting pollen from a wide range of plants. Pollen load analysis consistently identified pollens from more plant species and families from each bee species than direct observation of their foraging behaviour. After rarefaction to standardise pollen load sample sizes, diet breadth was significantly associated with frequency of occurrence, with more generalist bees present on more farms than less generalist bees. Our results show that the majority of bee species present on farmland in reasonable numbers are widely variable in their pollen choices, but that those with the broadest diet were present on the greatest number of farms. Increasing the diversity of plants included in agri-environment schemes may be necessary to provide a wider range of pollen resources in order to support a diverse bee community on farmland.     

Bumblebee Pupae Contain High Levels of Aluminium

The causes of declines in bees and other pollinators remains an on-going debate. While recent attention has focussed upon pesticides, other environmental pollutants have largely been ignored. Aluminium is the most significant environmental contaminant of recent times and we speculated that it could be a factor in pollinator decline. Herein we have measured the content of aluminium in bumblebee pupae taken from naturally foraging colonies in the UK. Individual pupae were acid-digested in a microwave oven and their aluminium content determined using transversely heated graphite furnace atomic absorption spectrometry. Pupae were heavily contaminated with aluminium giving values between 13.4 and 193.4 μg/g dry wt. and a mean (SD) value of 51.0 (33.0) μg/g dry wt. for the 72 pupae tested. Mean aluminium content was shown to be a significant negative predictor of average pupal weight in colonies. While no other statistically significant relationships were found relating aluminium to bee or colony health, the actual content of aluminium in pupae are extremely high and demonstrate significant exposure to aluminium. Bees rely heavily on cognitive function and aluminium is a known neurotoxin with links, for example, to Alzheimer’s disease in humans. The significant contamination of bumblebee pupae by aluminium raises the intriguing spectre of cognitive dysfunction playing a role in their population decline.     

Investigating the Foraging,Guarding and Drifting Behaviors of Commercial Bombus terrestris

Journal of Insect Behavior - Social insects have high levels of cooperation and division of labor. In bumble bees this is partly size-based, with larger bees performing tasks outside the nest and...     

Effects of Male age and Size on Mating Success in the Bumblebee Bombus terrestris

In social insects, the reproductive strategies adopted by colonies emerge as a complex property of individual behaviours, but as yet we are often unable to fully explain them in evolutionary terms. In bumblebees, colonies adopt either a short-lived strategy specializing in male production, or a longer-lived strategy in which mainly new queens are produced, but this results in males emerging long before mates are available; this strategy can only easily be explained if older males are at a significant reproductive advantage. Here we examine how age and morphological characters influence mating success of male bumblebees. In two separate experiments in which single virgin males and females were confined together, we found that young males and heavy males mated more swiftly and copulated for less time compared to old males or lighter males, respectively. However, in competitive situations age proved to be unimportant and the only factors to influence mating success were the lengths of the fore and hind tibiae, with strong directional selection for long leg length. Fore and hind legs are both used in courtship, so both traits are associated with plausible mechanisms under selection. It has previously been argued that, in times of food stress, bumblebee colonies should produce males as male size is less likely to be strongly correlated with fitness than female size. Our results suggest that this may not be so, since aspects of male size directly impact on their mating success. Our results leave unexplained the emergence of males many days before new queens.     

Discrimination of Unrewarding Flowers by Bees; Direct Detection of Rewards and Use of Repellent Scent Marks

Bumblebees and honeybees deposit short-lived scent marks on flowers that they visit when foraging. Conspecifics use these marks to distinguish those flowers that have recently been emptied and, so, avoid them. The aim of this study was to assess how widespread this behavior is. Evidence for direct detection of reward levels was found in two bee species: Agapostemon nasutus was able to detect directly pollen availability in flowers with exposed anthers, while Apis mellifera appeared to be able to detect nectar levels of tubular flowers. A third species, Trigona fulviventris, avoided flowers that had recently been visited by conspecifies, regardless of reward levels, probably by using scent marks. Three further bee/flower systems were examined in which there was no detectable discrimination among flowers. We argue that bees probably rely on direct detection of rewards where this is allowed by the structure of the flower and on scent marks when feeding on flowers where the rewards are hidden. However, discrimination does not always occur. We suggest that discrimination may not always make economic sense; when visiting flowers with a low handling time, or flowers that are scarce, it may be more efficient to visit every flower that is encountered.     

Molecular tools and bumble bees: revealing hidden details of ecology and evolution in a model system

Bumble bees are a longstanding model system for studies on behaviour, ecology and evolution, due to their well‐studied social lifestyle, invaluable role as wild and managed pollinators, and ubiquity and diversity across temperate ecosystems. Yet despite their importance, many aspects of bumble bee biology have remained enigmatic until the rise of the genetic and, more recently, genomic eras. Here, we review and synthesize new insights into the ecology, evolution and behaviour of bumble bees that have been gained using modern genetic and genomic techniques. Special emphasis is placed on four areas of bumble bee biology: the evolution of eusociality in this group, population‐level processes, large‐scale evolutionary relationships and patterns, and immunity and resistance to pesticides. We close with a prospective on the future of bumble bee genomics research, as this rapidly advancing field has the potential to further revolutionize our understanding of bumble bees, particularly in regard to adaptation and resilience. Worldwide, many bumble bee populations are in decline. As such, throughout the review, connections are drawn between new molecular insights into bumble bees and our understanding of the causal factors involved in their decline. Ongoing and potential applications to bumble bee management and conservation are also included to demonstrate how genetics‐ and genomics‐enabled research aids in the preservation of this threatened group.     

An economic model of the limits to foraging range in central place foragers with numerical solutions for bumblebees

1. A model is described that evaluates the maximum economic foraging range in central place foragers by using optimality criteria to discriminate between foraging sites at different distances from the forager's central place. 2. The basic model can be varied to suit foragers that optimise either their rate of net energy uptake or their foraging efficiency. 3. The model requires specification of the time and energy budgets of travel and foraging, and of the rewards obtainable at potential foraging sites. 4. The specific case of bumblebees, whose foraging ranges are poorly known, is considered. 5. Numerical solutions of the model for parameter values that represent bumblebees and their forage predict economic foraging ranges exceeding several kilometres. The model demonstrates that economics alone can explain extensive flight ranges in bees.