Gareth Bryning

Distinguishing signals and cues: bumblebees use general footprints to generate adaptive behaviour at flowers and nest

Chemicals used in communication are divided into signals and cues. Signals are moulded by natural selection to carry specific meanings in specific contexts. Cues, on the other hand, have not been moulded by natural selection to carry specific information for intended receivers. Distinguishing between these two modes of information transfer is difficult when animals do not perform obvious secretion behaviours. Although a number of insects have been suspected of leaving cues at food sites and nest entrances, studies have not attempted to experimentally distinguish between cues and signals. Here, we examine the chemical composition of the scent marks left by the bumblebee Bombus terrestris at food sites and compare it to those found at a neutral location. If bees are depositing a cue, we expect the same chemicals to be found at both sites, but if they deposit a signal we only expect to find the scent marks at the food site. We were also interested in identifying the chemicals left at the nest entrance to determine if they differed from those used to mark food sites. We find that bees deposit the same chemicals at food, nest and neutral sites. Therefore, bumblebees leave behind general chemical footprints everywhere they walk and we propose that they learn to use these footprints in a manner that ultimately enhances their fitness, for example, to improve their foraging efficiency and locate their nest. Experimentally, distinguishing these two modes of information transfer is crucial for understanding how they interact to shape animal behaviour and what chemical bouquets are under natural selection.

A Ranking of European Veterinary Medicines Based on Environmental Risks

ABSTRACT The most likely entry pathways of veterinary pharmaceuticals to the environment are via slurry or manure from intensively reared animals to soil and via dung or urine from animals grazing on pasture. These pathways may result in contamination of surface water via runoff or leaching and drainage. Direct entry into water may occur by defecation by pasture animals or by companion animals. In addition, application of medicines for aquaculture is important for a limited number of veterinary medicinal products. For a large number of veterinary medicinal products, consistent data on the environmental risk have never been generated. In this project, a simple risk-based ranking procedure was developed that should allow assessing the potential for environmental risks of active substances of veterinary medicinal products. In the European Union approximately 2000 products containing 741 active substances were identified. In the prescreening step and in agreement with the technical guidelines released by the European Medicines Agency, 294 natural substances, complex mixtures, and substances with low expected exposure were exempted from the ranking procedure. For 233 active substances, sufficient information was collated on 4 exposure scenarios: Intensively reared animals, pasture animals, companion animals, and aquaculture. The ranking approach was performed in 4 phases: 1) usage estimation; 2) characterization of exposure to soil, dung, surface water, and aquatic organisms depending on exposure scenarios; 3) characterization of effects based on therapeutical doses; and 4) risk characterization, which is the ratio of exposure to effects (risk index), and ranking. Generally, the top-ranked substances were from the antibiotic and parasiticide groups of veterinary medicines. Differences occurred in the ranking of substances in soil via application to either intensively reared or pasture animals. In intensive rearing, anticoccidia, for example, are used as feed-administered medicines (feed additives) in comparatively large doses over a long time. For pasture animals, these substances are used less, if at all, and therefore receive lower ranks. Besides that, the risk indices for the aquatic compartment are large for substances used in aquaculture or applied to companion animals. In conclusion, the ranking scheme developed for this project provided a scientifically based and pragmatic means of assessing the relative priority of veterinary medicines for further detailed risk assessment. The outcome of this project will support pharmaceutical industries and competent authorities when seeking authorization for market applications of veterinary pharmaceutical products.