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Diehl, Peter-Allan
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Diehl, Peter-Allan
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Ancien.ne collaborateur.trice
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Voici les éléments 1 - 2 sur 2
- PublicationAccès libreThe life-cycle of the bont tick Amblyomma hebraeum in vitro(1995)
; The life-cycle of the hard tick Amblyomma hebraeum was completed in vitro by feeding all life-stages of the tick through silicone membranes on bovine blood from an abattoir. Ticks were placed in a simple feeder consisting of a honey jar containing the blood with a glass tube insert (o.d. 42 mm) across the end of which the membrane was stretched. This feeding unit was held in a water bath (38°C). Larvae and nymphs fed on a membrane (<90 μm thick) made of silicone reinforced with Kodak® lens cleaning paper, and adults on a silicone membrane (0.5 mm thick) reinforced with Terylene® netting. To control microbial growth, gentamicin (5 μg/ml) and nystatin (100 i.u./ml) were added to the weekly open-collected blood, which was manually defibrinated. The blood was changed twice daily for nymphs and three times for adults and larvae. Attachment of ticks was induced with combinations of host hair, tick faeces, a bovine pelage extract and a synthetic aggregation-attachment pheromone mixture. The in vitro life-cycle started with unengorged “natural” adults, which had moulted from nymphs fed on steer. The life-cycle closed with unengorged, first in vitro generation adults which had moulted from nymphs fed in vitro. Although the feeding and development of larvae and nymphs were similar to in vivo controls, females fed and developed poorly in vitro. The toxicity of the systemic acaricide Ivermectin® for nymphs of A. hebraeum was confirmed using the in vitro feeding method. - PublicationAccès libreFeeding electrogram studies on the African cattle brown ear tick Rhipicephalus appendiculatus: evidence for an antifeeding effect of tick resistant serum(1992)
; Feeding behaviour of partially engorged Rhipicephalus appendiculatus (Neumann) (Acari: Ixodidae) on rabbit serum held in capillary tubes and placed over the tick mouthparts was studied using the feeding electrogram technique with simultaneous macro video photography. Correlation of electrical events with fluid movement in the vicinity of the tick's mouthparts and the capillary meniscus, permitted the characterization of an orderly sequence of signals, termed the ‘Feeding Complex’, associated with highest weight gains. This complex consisted of a 3–8 Hz fast-sucking waveform typically lasting 4–5 min, a sharp drop in potential at salivation, and rest lasting 1 or 2 min where no waveform or fluid movements occur. Very high impedence recordings from within the tick capitulum indicate that the fast-sucking waveform coincides with bursts of potentials corresponding to contraction of the pharyngeal dilator muscles, whereas during rest a tonic series of spikes signifies that the floor of the salivarium is actively lowered. Feeding electrograms of ticks fed on serum from tick-resistant rabbits showed significantly fewer feeding complexes. The weight gains achieved by these ticks were reduced correspondingly. This suggests that some of the humoral effectors of immunity have an antifeedant effect on this unusual parasite of rabbits.