The life-cycle of the bont tick Amblyomma hebraeum in vitro

Abstract

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.