Statistical modelling of conidial discharge of entomophthoralean fungi using a newly discovered Pandora species

Entomophthoralean fungi are insect pathogenic fungi and are characterized by their active discharge of infective conidia that infect insects. Our aim was to study the effects of temperature on the discharge and to characterize the variation in the associated temporal pattern of a newly discovered Pandora species with focus on peak location and shape of the discharge. Mycelia were incubated at various temperatures in darkness, and conidial discharge was measured over time. We used a novel modification of a statistical model (pavpop), that simultaneously estimates phase and amplitude effects, into a setting of generalized linear models. This model is used to test hypotheses of peak location and discharge of conidia. The statistical analysis showed that high temperature leads to an early and fast decreasing peak, whereas there were no significant differences in total number of discharged conidia. Using the proposed model we also quantified the biological variation in the timing of the peak location at a fixed temperature.Comment: 23 pages including supplementary materia

Statistical modelling of conidial discharge of entomophthoralean fungi using a newly discovered Pandora species

Entomophthoralean fungi are insect pathogenic fungi and are characterized by their active discharge of infective conidia that infect insects. Our aim was to study the effects of temperature on the discharge and to characterize the variation in the associated temporal pattern of a newly discovered Pandora species with focus on peak location and shape of the discharge. Mycelia were incubated at various temperatures in darkness, and conidial discharge was measured over time. We used a novel modification of a statistical model (pavpop), that simultaneously estimates phase and amplitude effects, into a setting of generalized linear models. This model is used to test hypotheses of peak location and discharge of conidia. The statistical analysis showed that high temperature leads to an early and fast decreasing peak, whereas there were no significant differences in total number of discharged conidia. Using the proposed model we also quantified the biological variation in the timing of the peak location at a fixed temperature

Effect of CO2 concentrations on entomopathogen fitness and insect-pathogen interactions

Numerous insect species and their associated microbial pathogens are exposed to elevated CO2 concentrations in both artificial and natural environments. However, the impacts of elevated CO2 on the fitness of these pathogens and the susceptibility of insects to pathogen infections are not well understood. The yellow mealworm, Tenebrio molitor, is commonly produced for food and feed purposes in mass-rearing systems, which increases risk of pathogen infections. Additionally, entomopathogens are used to control T. molitor, which is also a pest of stored grains. It is therefore important to understand how elevated CO2 may affect both the pathogen directly and impact on host-pathogen interactions. We demonstrate that elevated CO2 concentrations reduced the viability and persistence of the spores of the bacterial pathogen Bacillus thuringiensis. In contrast, conidia of the fungal pathogen Metarhizium brunneum germinated faster under elevated CO2. Pre-exposure of the two pathogens to elevated CO2 prior to host infection did not affect the survival probability of T. molitor larvae. However, larvae reared at elevated CO2 concentrations were less susceptible to both pathogens compared to larvae reared at ambient CO2 concentrations. Our findings indicate that whilst elevated CO2 concentrations may be beneficial in reducing host susceptibility in mass-rearing systems, they may potentially reduce the efficacy of the tested entomopathogens when used as biological control agents of T. molitor larvae. We conclude that CO2 concentrations should be carefully selected and monitored as an additional environmental factor in laboratory experiments investigating insect-pathogen interactions

L'intervention internationale au nom des droits de l'homme: L'autorité de l'approche finaliste

L'intervention internationale au nom des droits de l'homme, impliquant l'emploi unilatéral de la force d'un Etat dans la juridiction d'un autre Etat, peut-elle être admise au regard du droit international ? Nous proposons de résoudre cette question en nous intéressant à un dénominateur commun devant relier tout à la fois l'intention de l'intervenant, la Charte de l'ONU et la DUDH. Ce dénominateur se trouve dans une norme primordiale que nous appelons finaliste parce qu'elle postule que la réalisation universelle des droits de l'homme est souhaitable et possible. Nous vérifions par une démarche historique et épistémologique l'origine, la pertinence et la portée de cette norme ainsi que de son antithèse, la norme primordiale fataliste. Le jeu qu'entretiennent entre elles ces deux normes fait ressortir les intentions réelles de l'intervenant et découvrir un ensemble d'obligations implicites à la charge de ce dernier. Il permet de déterminer l'autorité juridique de l'intervenant

Preliminary results of survey on food safety aspects of drone brood from Apis mellifera L.

Drone brood removal is a common practice for the control of the honeybee parasite Varoa destructor in beehives of Apis mellifera L. in Switzerland and other European countries. At present, the removed drone brood is not used. The demand for alternative protein sources is growing and drone brood has a big potential to become a new food product and a new income for beekeepers. In contrast to insects currently produced for food, honeybees feed in an open system in the environment, which is difficult to control. Therefore, food borne pathogens from the environment on drone brood need to be assessed carefully. We analysed samples of drone brood from eight Swiss apiaries regarding important food borne pathogens. This survey gives a first overview on microbiological food safety of drone brood from A. mellifera. Based on our results, further studies will be conducted to develop a process of drone brood production that is safe regarding food borne pathogens

Bienenhaltung in der Schweiz.

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