Biology subjects

Brockmann, A.

Publications and source records attributed to Brockmann, A..

6 recordsLinked to original sources

bioRxiv2018

Species composition and altitudinal distribution of bumble bees (Hymenoptera: Apidae: Bombus) in the East Himalaya, Arunachal Pradesh, India

The East Himalaya is one of the worlds most biodiverse ecosystems. Yet, very little is known about the abundance and distribution of many plant and animal taxa in this region. Bumble bees are a group of cold-adapted and high altitude insects that fulfill an important ecological and economical function as pollinators of wild and agricultural flowering plants and crops. The Himalayan mountain range provides ample suitable habitats for bumble bees. Himalayan bumble bees have been studied systematically for a few decades now, with the main focus on the western region, while the eastern part of the mountain range received little attention and only a few species are genuinely reported. During a three-year survey, we collected more than 700 bumble bee specimens of 21 species in Arunachal Pradesh, the largest of the north-eastern states of India. We collected a range of species that were previously known from a very limited number of collected specimens, which highlights the unique character of the East Himalayan ecosystem. Our results are an important first step towards a future assessment of species distribution, threat and conservation. We observed clear altitudinal patterns of species diversity, which open important questions about the functional adaptations that allow bumble bees to thrive in this particularly moist region in the East Himalaya.

zoology↗

bioRxiv2018

Making honey bees lie: experimental dissociation of flight experience and dance communication.

Honey bees use their dance to communicate flight distance and direction of a food source to their nest mates in the hive. How bees transpose flight information to generate a corresponding walking (dance) behavior is still unknown. We now present a detailed study of the changes in dance duration of individual bees after shifting feeder distance. Our experiments indicated that most bees needed two or more foraging trips to the new position before showing an updated dance duration. In addition, only a few bees significantly changed dance duration immediately, whereas most bees first produced intermediary durations. Double shift experiments showed that under certain conditions bees do not update dance duration but continued to perform dance duration for the previously visited feeder position. We propose that generation of dance information involves two memory contents one for newly acquired and one for previously stored distance information.\n\nOne Sentence SummaryGeneration of dance information is temporally separated from immediate flight experience and involves two different memory contents.

animal behavior and cognition↗

bioRxiv2018

Investigating the viral ecology of global bee communities with high-throughput metagenomics

Bee viral ecology is a fascinating emerging area of research: viruses exert a range of effects on their hosts, exacerbate the impacts of other environmental stressors, and, importantly, are readily shared across multiple bee species in a community. However, our understanding of bee viral communities is limited, as it is primarily derived from studies of North American and European Apis mellifera populations. Here, we examined viruses in populations of A. mellifera and 11 other bee species from 9 countries, across 5 continents and Oceania. We developed a novel pipeline to rapidly, inexpensively, and robustly screen for bee viruses. This pipeline includes purification of encapsulated RNA/DNA viruses, sequence-independent amplification, high throughput sequencing, integrated assembly of contigs, and filtering to identify contigs specifically corresponding to viral sequences. We identified sequences corresponding to (+)ssRNA, (-)ssRNA, dsRNA, and ssDNA viruses. Overall, we found 127 contigs corresponding to novel viruses (i.e. previously not observed in bees), with 29 represented by >0.1 % of the reads in a given sample. These viruses and viral families were distributed across multiple regions and species. This study provides a robust pipeline for metagenomics analysis of viruses, and greatly expands our understanding of the diversity of viruses found in bee communities.

genomics↗

bioRxiv2018

Time-restricted foraging under natural light/dark condition shifts the molecular clock in the honey bee, Apis mellifera

Honey bees have a remarkable sense of time and individual honey bee foragers are capable to adjust their foraging activity with respect to the time of food availability. Although, there is plenty of experimental evidence that foraging behavior is guided by the circadian clock, nothing is known about the underlying cellular and molecular mechanisms. Here we present a first study exploring whether the time-restricted foraging under natural light-dark condition affects the molecular clock in honey bees. In an enclosed flight chamber (12m x 4m x 4m), food was presented either for 2 hours in the morning or 2 hours in the afternoon for several consecutive days and daily cycling of the two major clock genes, cryptochrome2 (cry2) and period (per), were analyzed in three different tissues involved in feeding-related behaviors: brain, antennae and subesophageal ganglion (SEG). We found that morning and afternoon trained foragers showed significant phase-differences in the cycling of both clock genes in all three tissues. Furthermore, the phase-differences were more pronounced when the feeder was scented with the general plant odor linalool. Our results clearly demonstrate that foraging time functions as a strong circadian Zeitgeber in honey bees. More surprisingly our results suggest that foraging time might have the potential to override the entrainment effect of the light-dark cycle.

neuroscience↗

bioRxiv2018

Regulation of individual differences in recruitment behaviour within honey bee foraging groups

Division of labour is a hallmark of eusocial insect colonies, with different groups of workers engaged in different tasks at the same time. Foraging is a task done by older workers in honey bee colonies. Foragers use the waggle dance behaviour to inform and recruit nest mates to food sources in the environment. The recruitment process incorporates information about the food reward, the colony food stores and the environmental food availability and plays a major role in ensuring efficient exploitation of the food sources available to the colony. However, the role that individual foragers play in driving recruitment is largely unexplored. We observed the dance activity of individual foragers from the same foraging group and showed that there are consistent inter-individual differences within a foraging group leading to a division of labour in the recruitment activity. Next, we studied the effect of changing social interactions on these individual differences. Removing foragers from the group led to an increase in the dance activity of the group of remaining foragers. This was mainly driven by an increase in the dance activity of certain individuals within the foraging groups. In contrast, allowing recruits to join the foraging group had a strong negative effect on the dance activity of all the individual foragers. Our study shows that there is a fine scale division of labour in the recruitment activity within foraging groups and that this is further regulated by changing social interactions. Thus, a complex interplay between individual differences and social interactions drive recruitment activity in honey bees.

animal behavior and cognition↗

bioRxiv2017

Sugar intake elicits a small-scale search behavior in flies and honey bees that involves capabilities found in large-scale navigation

Social insects, particularly bees and ants, show exceptional large-scale navigational skills to find and carry back food to their nests. Honey bees further evolved a symbolic communication to direct nest mates to attractive food sources. Till now it is unclear how these capabilities evolved. Sixty years ago, Vincent Dethier demonstrated that a small-scale sugar-elicited search behavior identified in flies shows remarkable similarities with honey bee dance behavior. Those findings suggested that both behaviors are based on common mechanisms and are likely evolutionary related. We now present for the first time a detailed comparison of the sugar-elicited search behavior in Drosophila melanogaster and Apis mellifera. In both species, intake of sugar elicits a complex of searching responses. The most obvious response was an increase in turning frequency, but more importantly we found that flies and honey bees returned to the location of the sugar drop. They even returned to the food location when we prevented them from using visual and chemosensory cues indicating that this small scale local search involves path integration mechanisms. Finally, we show that visual landmarks presented in the vicinity of the sugar drop affected the search trajectory and in honey bees the sugar intake induced learning of landmarks. Together, our experiments indicate that the sugar-elicited local search exhibits two major behavioral capabilities of large-scale navigation, path integration and landmark orientation.\n\nSignificance StatementTo search for food social insects evolved sophisticated strategies of spatial orientation and large-scale navigation. We now show that even a small-scale local search behavior in solitary flies and social honey bees involves path integration and landmark learning two major mechanisms of large-scale navigation. We propose that in the future sugar-elicited local search can be used to identify neural circuits involved in navigation, path integration, and landmark learning.

animal behavior and cognition↗