Generalization of navigation memory in honeybees

Flying insects like the honeybee learn multiple features of the environment for efficient navigation. Here we introduce a novel paradigm in the natural habitat, and ask whether the memory of such features is generalized to novel test conditions. Foraging bees from colonies located in 5 different home areas were tested in a common area for their search flights. The home areas differed in the arrangements of rising natural objects or their lack, and in the existence or lack of elongated ground structures. The test area resembled partly or not at all the layout of landmarks in the respective home areas. In particular, the test area lacked rising objects. The search flights were tracked with harmonic radar and quantified by multiples procedures, extracting their differences on an individual basis. Random search as the only guide for searching was excluded by two model calculations. The frequencies of directions of flight sectors differed from both model calculations and between the home areas in a graded fashion. Densities of search flight fixes were used to create heat maps and classified by a partial least squares regression analysis. Classification was performed with a support vector machine in order to account for optimal hyperplanes. A rank order of well separated clusters was found that partly resemble the graded differences between the ground structures of the home areas and the test area. The guiding effect of elongated ground structures was quantified with respect to the sequence, angle and distance from these ground structures. We conclude that foragers generalize their specific landscape memory in a graded way to the landscape features in the test area, and argue that both the existence and absences of landmarks are taken into account. The conclusion is discussed in the context of the learning and generalization process in an insect, the honeybee, with an emphasis on exploratory learning in the context of navigation

Detrimental effects of clothianidin on foraging and dance communication in honey bees

Ongoing losses of pollinators are of significant international concern because of the essential role they have in our ecosystem, agriculture, and economy. Both chemical and non-chemical stressors have been implicated as possible contributors to their decline, but the increasing use of neonicotinoid insecticides has recently emerged as particularly concerning. In this study, honey bees were exposed orally to sublethal doses of the neonicotinoid clothianidin in the field in order to assess its effects on the foraging behavior, homing success, and dance communication. The foraging span and foraging activity at the contaminated feeder decreased significantly due to chronic exposure at field-realistic concentrations. Electrostatic field of dancing bees was measured and it was revealed that the number of waggle runs, the fanning time and the number of stop signals were significantly lower in the exposed colony. No difference was found in the homing success and the flight duration between control and treated bees released at a novel location within the explored area. However, a negative effect of the ambient temperature, and an influence of the location of the trained feeder was found. Finally, the residues of clothianidin accumulated in the abdomens of exposed foraging bees over time. These results show the adverse effects of a chronic exposure to sublethal doses of clothianidin on foraging and dance communication in honey bees

Model Adaptation and Optimization for the Evaluation and Investigation of Novel Amine Blends in a Pilot-plant Scale CO2 Capture Process under Industrial Conditions

Carbon capture processes are highly energy intensive and the main driving force during the process design is the necessity to reduce the energy consumption for the solvent regeneration. The energy efficiency of absorption desorption processes is driven by the plant design and operation conditions, but also to a large extent by the choice of the scrubbing liquid (Wang et al., 2011). Absorbent screening for CO2 capture is timeconsuming and costly. Apart from the energy efficiency, aspects such as loading capacity and robustness towards industrial impurities and disturbances have to be investigated before designing a large-scale plant and optimally operating it. In this contribution, a systematic approach is presented to carry out evaluation tests for a novel solvent in an industrial pilot-plant and at the same time to determine an optimal operation point with maximum energy efficiency. The three-step approach is based on the assumption that for a novel absorbent little to no thermodynamic data is available. Hence, the investigation is solely based on simulation data from similar solvents and experimental data on the novel one. Monoethanolamine (MEA) still is widely used as reference absorbent for removing CO2. Consequently, simulation data and the properties of MEA are taken as a baseline for the general performance and behaviour of amine-based absorbents. As a first step, data from rigorous simulations is used to develop a surrogate model describing the general behaviour of a carbon capture process for MEA. Subsequently, pilot-plant-scale experiments are carried out to investigate the application of MEA in practice. Secondly, the surrogate model is then updated to account for the plant characteristics as given by the experimental data for MEA. Finally, by means of the MEA-based data-driven model, the new solvent is experimentally investigated. By successive approaches the surrogate model’s maximum in energy efficiency is identified and repeatedly updated for the novel solvent’s experimental behaviour. In terms of the energy efficiency and based on this workflow the performance of the novel solvent is compared with MEA

Honey bees infer source location from the dances of returning foragers

Honeybees (Apis mellifera carnica) communicate the direction and distance to a food source by means of a waggle dance. We ask whether bees recruited by the dance use it only as a flying instruction, with the technical form of a polar vector, or also translate it into a location vector that enables them to set courses directed toward the food source from arbitrary locations within their familiar territory. The flights of recruits captured on exiting the hive and released at distant sites were tracked by radar. The recruits performed first a straight flight in approximately the compass direction indicated by the dance. However, this “vector” portion of their flights and the ensuing tortuous “search” portion were strongly and differentially affected by the release site. Searches were biased toward the true location of the food and away from the location specified by translating the origin for the danced polar vector to the release site. We conclude that by following the dance recruits get two messages, a polar flying instruction (bearing and range from the hive) and a location vector that enables them to approach the source from anywhere in their familiar territory. The dance communication is much richer than thought so far

Eavesdropping on Honeybee Communication via Electrostatic Field Recordings

As a canary in a coalmine warns of dwindling breathable air, the honeybee can indicate the health of an ecosystem. Honeybees are the most important pollinators of fruit-bearing flowers, and share similar ecological niches with many other pollinators; therefore, the health of a honeybee colony can reflect the conditions of a whole ecosystem. The health of a colony may be mirrored in social signals that bees exchange during their sophisticated body movements such as the waggle dance. To observe these changes, we developed an automatic system that records and quantifies social signals under normal beekeeping conditions. Here, we describe the system and report representative cases of normal social behavior in honeybees. Our approach utilizes the fact that honeybee bodies are electrically charged by friction during flight and inside the colony, and thus they emanate characteristic electrostatic fields when they move their bodies. These signals, together with physical measurements inside and outside the colony (temperature, humidity, weight of the hive, and activity at the hive entrance) will allow quantification of normal and detrimental conditions of the whole colony. The information provided instructs how to setup the recording device, how to install it in a normal bee colony, and how to interpret its data

Contrasting Hydraulic Architectures of Scots Pine and Sessile Oak at Their Southernmost Distribution Limits

Many temperate European tree species have their southernmost distribution limits in the Mediterranean Basin. The projected climatic conditions, particularly an increase in dryness, might induce an altitudinal and latitudinal retreat at their southernmost distribution limit. Therefore, characterizing the morphological and physiological variability of temperate tree species under dry conditions is essential to understand species’ responses to expected climate change. In this study, we compared branch-level hydraulic traits of four Scots pine and four sessile oak natural stands located at the western and central Mediterranean Basin to assess their adjustment to water limiting conditions. Hydraulic traits such as xylem- and leaf-specific maximum hydraulic conductivity (KS-MAX and KL-MAX), leaf-to-xylem area ratio (AL:AX) and functional xylem fraction (FX) were measured in July 2015 during a long and exceptionally dry summer. Additionally, xylem-specific native hydraulic conductivity (KS-N) and native percentage of loss of hydraulic conductivity (PLC) were measured for Scots pine. Interspecific differences in these hydraulic traits as well as intraspecific variability between sites were assessed. The influence of annual, summer and growing season site climatic aridity (P/PET) on intraspecific variability was investigated. Sessile oak displayed higher values of KS-MAX, KL-MAX, AL:AX but a smaller percentage of FX than Scots pines. Scots pine did not vary in any of the measured hydraulic traits across the sites, and PLC values were low for all sites, even during one of the warmest summers in the region. In contrast, sessile oak showed significant differences in KS-MAX, KL-MAX, and FX across sites, which were significantly related to site aridity. The striking similarity in the hydraulic traits across Scots pine sites suggests that no adjustment in hydraulic architecture was needed, likely as a consequence of a drought-avoidance strategy. In contrast, sessile oak displayed adjustments in the hydraulic architecture along an aridity gradient, pointing to a drought-tolerance strategy

A unified platform to manage, share, and archive morphological and functional data in insect neuroscience

Insect neuroscience generates vast amounts of highly diverse data, of which only a small fraction are findable, accessible and reusable. To promote an open data culture, we have therefore developed the InsectBrainDatabase (IBdb), a free online platform for insect neuroanatomical and functional data. The IBdb facilitates biological insight by enabling effective cross-species comparisons, by linking neural structure with function, and by serving as general information hub for insect neuroscience. The IBdb allows users to not only effectively locate and visualize data, but to make them widely available for easy, automated reuse via an application programming interface. A unique private mode of the database expands the IBdb functionality beyond public data deposition, additionally providing the means for managing, visualizing, and sharing of unpublished data. This dual function creates an incentive for data contribution early in data management workflows and eliminates the additional effort normally associated with publicly depositing research data

Integrating biological vasculature into a multi-organ-chip microsystem

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.A chip-based system mimicking the transport function of the human cardiovascular system has been established at minute but standardized microsystem scale. A peristaltic on-chip micropump generates pulsatile shear stress in a widely adjustable physiological range within a microchannel circuit entirely covered on all fluid contact surfaces with human dermal microvascular endothelial cells. This microvascular transport system can be reproducibly established within four days, independently of the individual endothelial cell donor background. It interconnects two standard tissue culture compartments, each of 5 mm diameter, through microfluidic channels of 500 μm width. Further vessel branching and vessel diameter reduction down to a microvessel scale of approximately 40 μm width was realised by a two-photon laser ablation technique applied to inserts, designed for the convenient establishment of individual organ equivalents in the tissue culture compartments at a later time. The chip layout ensures physiological fluid-to-tissue ratios. Moreover, an in-depth microscopic analysis revealed the fine-tuned adjustment of endothelial cell behaviour to local shear stresses along the microvasculature of the system. Time-lapse and 3D imaging two-photon microscopy were used to visualise details of spatiotemporal adherence of the endothelial cells to the channel system and to each other. The first indicative long-term experiments revealed stable performance over two and four weeks. The potential application of this system for the future establishment of human-on-a-chip systems and basic human endothelial cell research is discussed.BMBF, 0315569, GO-Bio 3: Multi-Organ-Bioreaktoren für die prädiktive Substanztestung im Chipforma