Exposure to Sublethal Doses of Fipronil and Thiacloprid Highly Increases Mortality of Honeybees Previously Infected by Nosema ceranae

International audienceBACKGROUND: The honeybee, Apis mellifera, is undergoing a worldwide decline whose origin is still in debate. Studies performed for twenty years suggest that this decline may involve both infectious diseases and exposure to pesticides. Joint action of pathogens and chemicals are known to threaten several organisms but the combined effects of these stressors were poorly investigated in honeybees. Our study was designed to explore the effect of Nosema ceranae infection on honeybee sensitivity to sublethal doses of the insecticides fipronil and thiacloprid. METHODOLOGY/FINDING: Five days after their emergence, honeybees were divided in 6 experimental groups: (i) uninfected controls, (ii) infected with N. ceranae, (iii) uninfected and exposed to fipronil, (iv) uninfected and exposed to thiacloprid, (v) infected with N. ceranae and exposed 10 days post-infection (p.i.) to fipronil, and (vi) infected with N. ceranae and exposed 10 days p.i. to thiacloprid. Honeybee mortality and insecticide consumption were analyzed daily and the intestinal spore content was evaluated 20 days after infection. A significant increase in honeybee mortality was observed when N. ceranae-infected honeybees were exposed to sublethal doses of insecticides. Surprisingly, exposures to fipronil and thiacloprid had opposite effects on microsporidian spore production. Analysis of the honeybee detoxification system 10 days p.i. showed that N. ceranae infection induced an increase in glutathione-S-transferase activity in midgut and fat body but not in 7-ethoxycoumarin-O-deethylase activity. CONCLUSIONS/SIGNIFICANCE: After exposure to sublethal doses of fipronil or thiacloprid a higher mortality was observed in N. ceranae-infected honeybees than in uninfected ones. The synergistic effect of N. ceranae and insecticide on honeybee mortality, however, did not appear strongly linked to a decrease of the insect detoxification system. These data support the hypothesis that the combination of the increasing prevalence of N. ceranae with high pesticide content in beehives may contribute to colony depopulation

Power and temperature dependent model for High Q superconductors

Measuring the internal quality factor of coplanar waveguide superconducting resonators is an established method of determining small losses in superconducting devices. Traditionally, the resonator losses are only attributed to two-level system (TLS) defects using a power dependent model for the quality factor. However, excess non-equilibrium quasiparticles can also limit the quality factor of the planar superconducting resonators used in circuit quantum electrodynamics. At millikelvin temperatures, quasiparticles can be generated by breaking Cooper pairs via a single high-energy or multiple sub-gap photons. Here a two-temperature, power and temperature dependent model is proposed to evaluate resonator losses for isolating TLS and quasiparticle loss simultaneously. The model combines the conventional TLS power and temperature dependence with an effective temperature non-equilibrium quasiparticle description of the superconducting loss. The quasiparticle description is based on the quasiparticle number density calculated using rate equations for an external quasiparticle generation source, recombination, and trapping. The number density is translated to an effective temperature using a thermal distribution that may be different from the bath. Experimental measurements of high-quality factor resonators fabricated from single crystal aluminum and titanium nitride thin films on silicon are interpreted with the presented model. This approach enables identification of quasiparticle and TLS loss, resulting in the determination that the TiN resonator has comparable TLS and quasiparticle loss at low power and low-temperature, while the low-temperature Al resonator behavior is dominated by non-equilibrium quasiparticle loss

Evaluation of a biological risk management tool on large western United States dairies

Critical to changing biosecurity practices on the farm is an individual assessment of those practices contributing to disease transmission. The purpose of this project was to assess, implement, and refine a biological risk management survey for use on large western United States dairy farms. Assessment tools developed by Iowa State University Center for Food Security and Public Health (Ames, IA) were refined using a focus group process and by testing them on 40 dairy herds in California. Each question was evaluated using standard criteria and producer responses. Some survey questions required refinement for clarity and others were considered unnecessary. New questions were added based on a biosecurity literature review, resulting in a new set of questions that can be used by extension educators and food animal veterinarians to help identify disease risk areas and educate dairy producers

Cuticular hydrocarbons as a basis for chemosensory self-referencing in crickets : a potentially universal mechanism facilitating polyandry in insects

Females of many species obtain benefits by mating polyandrously, and often prefer novel males over previous mates. However, how do females recognise previous mates, particularly in the face of cognitive constraints? Female crickets appear to have evolved a simple but effective solution: females imbue males with their own cuticular hydrocarbons (CHCs) at mating and utilise chemosensory self-referencing to recognise recent mates. Female CHC profiles exhibited significant additive genetic variation, demonstrating that genetically unique chemical cues are available to support chemosensory self-referencing. CHC profiles of males became more similar to those of females after mating, indicating physical transfer of CHCs between individuals during copulation. Experimental perfuming of males with female CHCs resulted in a female aversion to males bearing chemical cues similar to their own. Chemosensory self-referencing, therefore, could be a widespread mechanism by which females increase the diversity of their mating partners

EXPLORING THE VIBRATIONAL STRUCTURE OF THE VINYLIDENE ANION USING ARGON PREDISSOCIATION SPECTROSCOPY

Author Institution: Sterling Chemistry Laboratory, Yale Universtiy, PO Box 208107, New Haven, CT 06520We report Ar-mediated vibrational spectra of the vinylidene anion, a relevant intermediate in various chemical processes, and its fully deuterated form in order to characterize the vibrational energy levels present in this species. Identification of the C-H asymmetric and symmetric stretching frequencies was made and confirmed by the deuterium isotope shift. This information could then be used to clarify the origin of two higher energy peaks around 4000 and 4200 cm^-^1 in the light isotope, which occur quite close to the photodetachment threshold. Preliminary analysis indicates their assignment to combination bands involving excitation of the C=C stretch along with the C-H fundamentals. The work was then extended to include the NNO molecule as a messenger species