Winter Active Bumblebees (Bombus terrestris) Achieve High Foraging Rates in Urban Britain

Background: Foraging bumblebees are normally associated with spring and summer in northern Europe. However, there have been sightings of the bumblebee Bombus terrestris during the warmer winters in recent years in southern England. But what floral resources are they relying upon during winter and how much winter forage can they collect? Methodology/Principal Findings: To test if urban areas in the UK provide a rich foraging niche for bees we set up colonies of B. terrestris in the field during two late winter periods (2005/6 & 2006/7) in London, UK, and measured their foraging performance. Fully automatic radio-frequency identification (RFID) technology was used in 2006/7 to enable us to record the complete foraging activity of individually tagged bees. The number of bumblebees present during winter (October 2007 to March 2008) and the main plants they visited were also recorded during transect walks. Queens and workers were observed throughout the winter, suggesting a second generation of bee colonies active during the winter months. Mass flowering shrubs such as Mahonia spp. were identified as important food resources. The foraging experiments showed that bees active during the winter can attain nectar and pollen foraging rates that match, and even surpass, those recorded during summer. Conclusions/Significance: B. terrestris in the UK are now able to utilise a rich winter foraging resource in urban parks and gardens that might at present still be under-exploited, opening up the possibility of further changes in pollinato

What evidence exists on the impacts of large herbivores on climate change? A systematic map protocol

Background- In recent years there has been an increased focus on the role of large herbivores in ecosystem restoration and climate change mitigation. There are multiple processes by which large herbivores could potentially influence climate feedback and forcing effects, but the evidence has not yet been synthesised in a systematic and accessible format. Grazing, browsing, trampling, defecation, and seed dispersal by large herbivores can influence vegetation and soils in ways that may directly or indirectly contribute to climate change or mitigation. For example, changes in vegetation could impact wildfire regimes, carbon storage, and albedo, with ultimate impacts on climate. These processes may be influenced by herbivore species composition, density, and functional traits. The main aim of this systematic map is to synthesise the range of research on climate feedback and forcing effects from large herbivores (≥ 10 kg) in terrestrial ecosystems. We also aim to identify knowledge clusters and gaps in the research base, as well as assessing the potential for quantitative analyses. Methods- A search of peer-reviewed and grey literature will be conducted using a range of bibliographic databases, search engines and websites. The search strategy will involve using a pre-defined search string with Boolean operators. All search results will be screened for relevance according to specific eligibility criteria. Screening will be conducted in two stages: all articles will initially be screened by title and abstract, then those that meet the eligibility criteria will be screened by full text. At both stages, articles will be excluded if they don’t meet all eligibility criteria or if they meet any exclusion criteria. All articles included as eligible after full text screening will be coded. At each stage (of screening and coding) a proportion of articles will be processed independently by two reviewers to assess inter-reviewer reliability and resolve differences. The evidence will be presented in a searchable database with accompanying visual outputs. A narrative synthesis will be provided outlining the range and distribution of evidence, knowledge gaps and clusters, potential bias, and areas for further research

Anthropogenic noise disrupts mate searching in Gryllus bimaculatus

Many animals use acoustic communication as a means of sending important biological information, such as their location, to potential receivers. However, anthropogenic noise is known to affect the ability of some species to either produce or receive signals, which may influence their reproductive success. In this study, we investigate the effect of anthropogenic noise on the mate searching behaviors of the field cricket Gryllus bimaculatus. To accomplish this, phonotaxis trials were conducted with female field crickets under different acoustic conditions, and their ability to detect and move towards conspecific male calls was assessed. The presence of traffic noise reduced the likelihood that the female would approach the male calls and also reduced the time that the female spent attending to the calling stimulus before making her decision. However, the presence of white noise did not reduce the likelihood of approaching the calling speaker, indicating that the average amplitude of anthropogenic noise is, alone, not important in this conflict, but frequency and fluctuations in the stimulus or other characteristic might be. This study supports the hypothesis that anthropogenic noise does indeed influence the detectability of acoustic mate location signals, thus disrupting mate searching behavior

Spatio-temporal dynamics of bumblebees foraging under predation risk

We analyze 3D flight paths of bumblebees searching for nectar in a laboratory experiment with and without predation risk from artificial spiders. For the flight velocities we find mixed probability distributions reflecting the access to the food sources while the threat posed by the spiders shows up only in the velocity correlations. The bumblebees thus adjust their flight patterns spatially to the environment and temporally to predation risk. Key information on response to environmental changes is contained in temporal correlation functions, as we explain by a simple emergent model.Comment: Accepted for publication in PR

Zooming into plant-flower visitor networks: an individual trait-based approach

Understanding how ecological communities are structured is a major goal in ecology. Ecological networks representing interaction patterns among species have become a powerful tool to capture the mechanisms underlying plant-animal assemblages. However, these networks largely do not account for inter-individual variability and thus may be limiting our development of a clear mechanistic understanding of community structure. In this study, we develop a new individual-trait based approach to examine the importance of individual plant and pollinator functional size traits (pollinator thorax width and plant nectar holder depth) in mutualistic networks. We performed hierarchical cluster analyses to group interacting individuals into classes, according to their similarity in functional size. We then compared the structure of bee-flower networks where nodes represented either species identity or trait sets. The individual trait-based network was almost twice as nested as its species-based equivalent and it had a more symmetric linkage pattern resulting from of a high degree of size-matching. In conclusion, we show that by constructing individual trait-based networks we can reveal important patterns otherwise difficult to observe in species-based networks and thus improve our understanding of community structure. We therefore recommend using both trait-based and species-based approaches together to develop a clearer understanding of the properties of ecological networks

Speed-Accuracy Tradeoffs and False Alarms in Bee Responses to Cryptic Predators

SummaryLearning plays a crucial role in predator avoidance [1–3], but little is known about how the type of experience with predators molds future prey behavior. Specifically, is predator-avoidance learning and memory retention disrupted by cryptic coloration of predators, such as crab spiders [4, 5]? How does experience with different predators affect foraging decisions? We evaluated these questions by exposing foraging bumblebees to controlled predation risk from predators (robotic crab spiders) that were either cryptic or highly contrasting, as assessed by a quantitative model of bee color perception [6]. Our results from 3D tracking software reveal a speed-accuracy tradeoff [7]: Bees slow their inspection flights after learning that there is a risk from cryptic spiders. The adjustment of inspection effort results in accurate predator detection, leveling out predation risk at the expense of foraging time. Overnight-retention tests reveal no decline in performance, but bees that had experienced cryptic predators are more prone to “false alarms” (rejection of foraging opportunities on safe flowers) than those that had experienced conspicuous predators. Therefore, bees in the cryptic-spider treatment made a functional decision to trade off reduced foraging efficiency via increased inspection times and false-alarm rates against higher potential fitness loss from being injured or eaten

The genomes of two key bumblebee species with primitive eusocial organization

Background: The shift from solitary to social behavior is one of the major evolutionary transitions. Primitively eusocial bumblebees are uniquely placed to illuminate the evolution of highly eusocial insect societies. Bumblebees are also invaluable natural and agricultural pollinators, and there is widespread concern over recent population declines in some species. High-quality genomic data will inform key aspects of bumblebee biology, including susceptibility to implicated population viability threats. Results: We report the high quality draft genome sequences of Bombus terrestris and Bombus impatiens, two ecologically dominant bumblebees and widely utilized study species. Comparing these new genomes to those of the highly eusocial honeybee Apis mellifera and other Hymenoptera, we identify deeply conserved similarities, as well as novelties key to the biology of these organisms. Some honeybee genome features thought to underpin advanced eusociality are also present in bumblebees, indicating an earlier evolution in the bee lineage. Xenobiotic detoxification and immune genes are similarly depauperate in bumblebees and honeybees, and multiple categories of genes linked to social organization, including development and behavior, show high conservation. Key differences identified include a bias in bumblebee chemoreception towards gustation from olfaction, and striking differences in microRNAs, potentially responsible for gene regulation underlying social and other traits. Conclusions: These two bumblebee genomes provide a foundation for post-genomic research on these key pollinators and insect societies. Overall, gene repertoires suggest that the route to advanced eusociality in bees was mediated by many small changes in many genes and processes, and not by notable expansion or depauperation

Data from: Anthropogenic noise disrupts mate searching in Gryllus bimaculatus

Many animals use acoustic communication as a means of sending important biological information, such as their location, to potential receivers. However, anthropogenic noise is known to affect the ability of some species to either produce or receive signals, which may influence their reproductive success. In this study, we investigate the effect of anthropogenic noise on the mate searching behaviors of the field cricket Gryllus bimaculatus. To accomplish this, phonotaxis trials were conducted with female field crickets under different acoustic conditions, and their ability to detect and move towards conspecific male calls was assessed. The presence of traffic noise reduced the likelihood that the female would approach the male calls and also reduced the time that the female spent attending to the calling stimulus before making her decision. However, the presence of white noise did not reduce the likelihood of approaching the calling speaker, indicating that the average amplitude of anthropogenic noise is, alone, not important in this conflict, but frequency and fluctuations in the stimulus or other characteristic might be. This study supports the hypothesis that anthropogenic noise does indeed influence the detectability of acoustic mate location signals, thus disrupting mate searching behavior