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Guerin, Patrick

Nom
Guerin, Patrick
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patrick.guerin@unine.ch
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https://libra.unine.ch/handle/123456789/310

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  • Publication
    Accès libre
    Aliphatic alcohols and aldehydes of the honey bee cocoon induce arrestment behavior in Varroa jacobsoni (Acari: Mesostigmata), an ectoparasite of Apis mellifera
    (Wiley, 1998)
    Donzé, Gérard
    ;
    Silvia Schnyder
    ;
    Bogdanov, Stefan
    ;
    Diehl, Peter-Allan 
    ;
    Guerin, Patrick 
    ;
    Kilchenman, Verena
    ;
    Monachon, Florian
    The ectoparasitic mite Varroa jacobsoni reproduces in the capped brood of the honey bees Apis cerana and Apis mellifera. Observations on the reproductive behavior of the mite have shown a well-structured spatial allocation of its activity using the bee or cell wall for different behaviors. The resulting advantages for the parasite of this subdivision of the concealed brood environment suggests an important role for chemostimuli in these substrates.
    Extracts of the European honey bee cocoons induce a strong arrestment response in the mite, as indicated by prolonged periods of walking on the extracts applied on a semipermeable membrane and by systematically returning to the stimulus after encountering the treatment borders. Two thin-layer chromatography fractions of the cocoon extract eliciting arrestment were found to contain saturated C17 to C22 primary aliphatic alcohols and C19 to C22 aldehydes.
    We analyzed extracts of the cocoon and different larvae, pupae, and adults of both worker and drone A. mellifera to determine the relative amounts of these chemostimuli in the different substrates employed by Varroa. Both aldehydes and alcohols were more abundant in the cocoon than in the cuticle of adult or developing bees.
    Mixtures of the aliphatic alcohols and aldehydes at the proportions found in the cocoons acted synergistically on the arrestment response, but this activity disappeared when mixed in equal amounts. When these oxygenated chemostimuli were mixed with C19 to C25 alkanes at the proportions found in the cocoon extract, we observed a significantly lower threshold for the chemostimulant mixture. These results indicate how Varroa may use mixtures of rarer products to differentiate between substrates and host stages during its developmental cycle within honey bee brood cells.
  • Publication
    Accès libre
    Cuticle alkanes of honeybee larvae mediate arrestment of bee parasite Varroa jacobsoni
    (1994)
    Rickli, M.
    ;
    Diehl, Peter-Allan 
    ;
    Guerin, Patrick 
    The ectoparasitic mite Varroa jacobsoni invades worker brood cells of the honeybee Apis mellifera during the last 20 hr before the cells are sealed with a wax cap. Cuticle extracts of 8-day-old worker honeybee larvae occupying such brood cells have an arrestment effect on the mite. The mites run for prolonged periods on the extract, systematically returning onto the stimulus after touching the borders of the treated area. Mites increase walking speed and path straightness in response to increasing doses of a nonpolar fraction of the cuticle extract. Saturated straight-chain odd-numbered C19–C29 hydrocarbons were identified by thin-layer argentation chromatography and gas chromatography-mass spectrometry as the most active constituents, with branched alkanes also contributing to the arrestment effect of this active fraction. Analysis of the behavior responses to synthetic n-alkanes indicate that the response is probably based on a synergism between the different alkane components of the fraction rather than to an individual compound.