No abstract

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.

Several aspects of the biology of the tomato moth, Lacanobia oleracea (Linnaeus) were investigated when these insects were fed an artificial diet and kept under laboratory conditions. The six larval stadia occupied a total period of 35.6 days at 20°C and 65% r.h. Larvae of each stadium could be separated by their head capsule widths, but not weight ranges, which overlapped. Feeding studies carried out on larval L. oleracea revealed instar dependent changes in the indices of food consumption and utilization. Larvae increased in weight from the fourth to sixth instar due to a combination of the increased efficiency with which ingested food was converted to body tissue, and increased food consumption by older larvae. Sixth (final) instar larvae exhibited three distinct behavioural phases; during one of these, the feeding phase, larvae consumed a greater amount of diet than either the fourth or fifth instars. The mean pupal period of non-diapausing pupae was 25 days. Pupal diapause was induced when larvae were reared under short day conditions. The male to female sex ratio of adult moths was 1:1.3. Mating generally began during the first scotophase after adult eclosion, and stopped soon after the start of the next photophase. Females usually mated only once, but males were capable of mating at least seven times. Oviposition normally commenced on day 2 of adult life, and the mean total egg production was 1186 eggs/female. Sex pheromone components were not present in solvent extracts of the pheromone glands of 20-day-old female pupae, but low levels were detected in pharate adults. A further increase in pheromone levels in newly-emerged moths was detected and, in isolated virgin moths, pheromone levels increased each day of adult life until day 9. Pheromone levels were significantly lower in two-day-old mated adult females, than in two-day-old virgins.

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 Scompanion 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.

The sex pheromone released by the adult female Tenebrio molitor, 4-methyl-1-nonanol, is well known. In addition, there is evidence that adult males release a pheromone that attracts females. The purpose of the present study was to isolate and identify male-released pheromone(s). Emissions from virgin adult males and females were collected on filter paper and extracted with pentane. Extracts were analyzed by gas chromatography-mass spectrometry. One male-specific compound was detected and identified as (Z)-3-dodecenyl acetate (Z3-12:Ac). In arena bioassays, E3-12:Ac was attractive to females only, at 1 and 10 microg doses. E3-12:Ac was also attractive to females at a 10-microg dose. The presence of both male and female pheromones, each attracting the opposite sex, may contribute to maintaining a high-density population of both sexes.