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Guerin, Patrick

Nom
Guerin, Patrick
Affiliation principale
Site web
Fonction
Professeur associé
Email
patrick.guerin@unine.ch
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https://libra.unine.ch/handle/123456789/310

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  • Publication
    Accès libre
    The Tick Blood Meal: From a Living Animalor from a Silicone Membrane ?
    (2007)
    Kröber, Thomas
    ;
    Guerin, Patrick 
    An artificial feeding unit with a reinforced silicone membrane to replace host skin provides ticks with a perch over blood with a tick attachment rate of 75-100%. Some 5 mg of an acaricide like fipronil is sufficient to establish survival curves over different doses down to ppb levels in blood. This in vitro feeding assay for hard ticks is more advantageous than in vivotrials on animals.
  • Publication
    Accès libre
    Darkness induces mobility, and saturation deficit limits questing duration, in the tick Ixodes ricinus
    (2003)
    Perret, Jean-Luc
    ;
    Guerin, Patrick 
    ;
    Diehl, Peter-Allan 
    ;
    Vlimant, Michèle 
    ;
    Gern, Lise 
    The behaviour of Ixodes ricinus nymphs was recorded in 10-day experiments using computer-assisted video-tracking, in the absence of any host stimuli. These ticks switch spontaneously from questing in a desiccating atmosphere to quiescence in a water-saturated atmosphere after dark. Quantification of both questing and quiescence duration demonstrates that questing duration is inversely related to saturation deficit whereas quiescence duration is not. Distance walked after quiescence increased with desiccating conditions, while the distance walked after questing remained unchanged. Almost all locomotor activities of I. ricinus occurred during darkness under either a 14 h:10 h L:D or a 8 h:4 h L:D cycle. We established that all life stages of I. ricinus are equipped to sense shifts in light intensity with bilaterally placed strings of photoreceptors. This permits I. ricinus to use onset of darkness to trigger mobility when desiccation risk is reduced in nature.
  • Publication
    Accès libre
    In vitro assays for repellents and deterrents for ticks: differing effects of products when tested with attractant or arrestment stimuli
    (2003)
    McMahon, Conor
    ;
    Kröber, Thomas
    ;
    Guerin, Patrick 
    Most in vivo and in vitro tests with repellents or deterrents against ticks have not considered which sensory channel is being targeted. We have recorded the responses of two hard tick species (Acari: Ixodidae) in vitro to determine if such products can disrupt the perception of an attractant in a repellent assay or the perception of an arrestment stimulus in a deterrent assay. Ethyl butylacetylaminopropionate (EBAAP), N,N-diethyl-methyl-benzamide (deet), permethrin and indalone were chosen to test their capacity to inhibit the attraction of Amblyomma variegatum Fabricius to its aggregation-attachment pheromone. Vapours of each test product plus those from a synthetic blend of the pheromone were delivered to the walking tick in an air stream on a locomotion compensator. Neither EBAAP, deet, permethrin nor indalone could inhibit attraction of A. variegatum even when each of the test products was delivered at 106 times the pheromone. Indalone did decrease the attraction of A. variegatum to the pheromone and induced repulsion of A. variegatum when presented on its own in the air stream. The effect of permethrin, a sodium channel blocker, was also tested in a deterrent assay measuring the arrestment of Ixodes ricinus (L.) adults on its own faeces and faecal constituents. Permethrin deterred arrestment at doses of 670 fg/cm2 to 67 ng/cm2, i.e. at levels five times lower than the dose of chemostimuli present in the arrestment stimulus. This sensitivity to permethrin suggests that it acts via the contact chemoreception channel.
  • Publication
    Accès libre
    The Dynamics of an Avoidance Behavior by Ixodid Ticks to Liquid Water
    (2000)
    Kröber, Thomas
    ;
    Guerin, Patrick 
    Life stages of different tick species avoid walking on a wet surface surrounding a dry patch by systematically returning to the dry each time they contact the wet surface beyond the border with the tip of a first leg tarsus. Sequential analysis of the border behaviors shows that repetitive contact with the water increases the probability of walks astride the border. Ticks accept this unilateral contact with the water for longer intervals and eventually walk on to the wet surface after a combination of a short patch walk followed by a border walk which is longer than the foregoing ones. Staying time on a small circular patch is shorter than on a large one, arising probably from faster adaptation of peripheral receptors following a higher frequency of border contacts. However, an equal number of border reactions on patches of different sizes and shapes suggests that a counter in the CNS may also influence dry patch departure.
  • Publication
    Accès libre
    Contact chemostimuli in the mating behaviour of the cattle tick, Boophilus microplus
    (1999)
    de Bruyne, Marien
    ;
    Guerin, Patrick 
    Mating of the cattle tick Boophilus microplus is mediated by chemical stimuli on the cuticle of females. Males are arrested on the dorsum of females attached to the host, frequently sample the substrate, and then tip-over to the ventrally located gonopore. These behaviours are also observed in vitro when males are placed on a small glass bead treated with a female extract. Time spent and tip-over by male ticks on dummies is used in an assay to test the behavioural significance of fractions of the extract. TLC separation yields one apolar fraction that arrests males, though much less so than the whole extract, but lost tip-over behaviour. This apolar fraction contains a series of cholesteryl esters that, when tested individually, show no arrestment activity at levels present in the extract but, when combined, are as active as the fraction. When a small silica column is used for fractionation, all biological activity is reproduced after recombining the fractions. In addition to the early eluting apolar fraction containing cholesteryl esters, a set of highly active more polar fractions is isolated. Electrophysiological recordings from gustatory sensilla on the pedipalps of male B. microplus, which are regularly brought into contact with the cuticle of the female during mating, provide evidence for receptors in two of them responding to the whole extract and to the behaviourally active polar fractions. Mating behaviour involving arrestment and tip-over is clearly initiated by a mixture of chemical stimuli, and tip-over behaviour is associated with the more polar material.
  • Publication
    Accès libre
    Ixodid ticks avoid contact with liquid water
    (1999)
    Thomas Kröber
    ;
    Guerin, Patrick 
    Larvae of the cattle tick Boophilus microplus and all life stages of the European sheep tick Ixodes ricinus avoid walking on a wet membrane surface surrounding a dry patch. Of 170 reactions made at a border with liquid water by 22 B. microplus larvae, 40% consisted of immediate turns to the opposite side to bring all the legs back onto a dry patch, 41% were walks along the border, during which the ticks maintained contact with both the dry and wet zones, and 19% were returns to the dry patch after a short excursion onto the wet surround. Since contact with one front leg tip was sufficient to cause return reactions from the wet surface in most of the border contacts, the water receptor(s) that enable ticks to perceive the wet surface are probably located in terminal pore sensilla on the first-leg tarsi. Observations on the return reactions of ticks with different groups of chemosensilla masked confirmed this. Ticks have an ambiguous relationship with water: they appear to avoid direct contact with it, but they need a high humidity to compensate for any deficit in body water.