Spider Movement, UV Reflectance and Size, but Not Spider Crypsis, Affect the Response of Honeybees to Australian Crab Spiders

According to the crypsis hypothesis, the ability of female crab spiders to change body colour and match the colour of flowers has been selected because flower visitors are less likely to detect spiders that match the colour of the flowers used as hunting platform. However, recent findings suggest that spider crypsis plays a minor role in predator detection and some studies even showed that pollinators can become attracted to flowers harbouring Australian crab spider when the UV contrast between spider and flower increases. Here we studied the response of Apis mellifera honeybees to the presence of white or yellow Thomisus spectabilis Australian crab spiders sitting on Bidens alba inflorescences and also the response of honeybees to crab spiders that we made easily detectable painting blue their forelimbs or abdomen. To account for the visual systems of crab spider's prey, we measured the reflectance properties of the spiders and inflorescences used for the experiments. We found that honeybees did not respond to the degree of matching between spiders and inflorescences (either chromatic or achromatic contrast): they responded similarly to white and yellow spiders, to control and painted spiders. However spider UV reflection, spider size and spider movement determined honeybee behaviour: the probability that honeybees landed on spider-harbouring inflorescences was greatest when the spiders were large and had high UV reflectance or when spiders were small and reflected little UV, and honeybees were more likely to reject inflorescences if spiders moved as the bee approached the inflorescence. Our study suggests that only the large, but not the small Australian crab spiders deceive their preys by reflecting UV light, and highlights the importance of other cues that elicited an anti-predator response in honeybees

Processing of Body Odor Signals by the Human Brain

Brain development in mammals has been proposed to be promoted by successful adaptations to the social complexity as well as to the social and non-social chemical environment. Therefore, the communication via chemosensory signals might have been and might still be a phylogenetically ancient communication channel transmitting evolutionary significant information. In humans, the neuronal underpinnings of the processing of social chemosignals have been investigated in relation to kin recognition, mate choice, the reproductive state and emotional contagion. These studies reveal that human chemosignals are probably not processed within olfactory brain areas but through neuronal relays responsible for the processing of social information. It is concluded that the processing of human social chemosignals resembles the processing of social signals originating from other modalities, except that human social chemosignals are usually communicated without the allocation of attentional resources, that is below the threshold of consciousness. Deviances in the processing of human social chemosignals might be related to the development and maintenance of mental disorders

Targeting Trained Innate Immunity With Nanobiologics to Treat Cardiovascular Disease

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A meta-analysis of predation risk effects on pollinator behaviour

Flower-visiting animals are constantly under predation risk when foraging and hence might be expected to evolve behavioural adaptations to avoid predators. We reviewed the available published and unpublished data to assess the overall effects of predators on pollinator behaviour and to examine sources of variation in these effects. The results of our meta-analysis showed that predation risk significantly decreased flower visitation rates (by 36%) and time spent on flowers (by 51%) by pollinators. The strength of the predator effects depended neither on predator taxa and foraging mode (sit-and-wait or active hunters) nor on pollinator lifestyle (social vs. solitary). However, predator effects differed among pollinator taxa: predator presence reduced flower visitation rates and time spent on flowers by Squamata, Lepidoptera and Hymenoptera, but not by Diptera. Furthermore, larger pollinators showed weaker responses to predation risk, probably because they are more difficult to capture. Presence of live crab spiders on flowers had weaker effects on pollinator behaviour than presence of dead or artificial crab spiders or other objects (e.g. dead bees, spheres), suggesting that predator crypsis may be effective to some extent. These results add to a growing consensus on the importance of considering both predator and pollinator characteristics from a community perspective

Reliability of non-invasive cardiac output measurement in individuals with tetraplegia

Study design:The study is conducted on the basis of comparative-repeated measures.Objectives:The objective of this study is to assess the reliability of non-invasive cardiac output (CO) measurements in individuals with tetraplegia (TP) at rest and during exercise using Innocor, and to test the hypothesis that CO measurements are less reliable in TP than in able-bodied (AB) individuals.Setting:Ambulatory volunteers, Switzerland.Methods:Nine male motor-complete TP (C5-C7) and nine pair-matched AB performed repeated CO measurements at rest and during submaximal arm-crank and wheelchair exercises in four different test sessions. Within- and between-day reliabilities were compared between TP and AB.Results:Mean differences between measurements at rest (TP vs AB, within-day: 0.1±0.5 vs 0.2±0.6 l min(-1), between-day: -0.7±0.6 vs -0.1±0.8 l min(-1)), during arm-crank (TP vs AB, within-day: 0.1±0.9 vs 0.5±0.7 l min(-1), between-day: -0.3±1.1 vs 0.0±1.1 l min(-1)) and wheelchair exercises (TP vs AB, within-day: 0.3±1.2 vs -0.1±0.8 l min(-1), between-day: 0.1±1.1 vs 0.5±0.9 l min(-1)) were not significantly different between TP and AB (all P>0.05). Coefficients of variation in TP (within-day, rest: 6.8%, arm-crank: 9.6% and wheelchair: 10.8%; between-day, rest: 11.9%, arm-crank: 11.2% and wheelchair: 10.3%) and in AB (within-day, rest: 7.7%, arm crank: 6.8% and wheelchair: 6.0%; between-day, rest: 9.2%, arm crank: 8.5% and wheelchair: 8.0%) indicated acceptable reliability.Conclusion:In contrast to our hypothesis, we found non-invasive CO measurements using Innocor to be as reliable in TP as they are in AB. Consequently, Innocor can be recommended for repeated assessments of CO in TP within routine diagnostics or for evaluation of training progress.Sponsorship:The study was supported by the Swiss National Science Foundation (Grant no. 32-116777).Spinal Cord advance online publication, 21 December 2010; doi:10.1038/sc.2010.173