Lipid consumption in ixodes ricinus (acari : ixodidae): temperature and potential longevity

The effect of temperature on the rate of consumption of the lipid reserves in Ixodes ricinus Linnaeus was characterized in constant temperature experiments. There was a consistent linear relationship between temperature and lipid consumption in nymphs and adult females and males between 5 and 37°C. Nymphs and adults were able to withstand extended periods of exposure to temperatures within the range of 2-37°C, although at 2°C there was evidence of thermal stress. The variance about the median rate of lipid consumption was found to increase with increasing rate of lipid consumption. Predictions of longevity were made using the rates of lipid consumption for the three stages studied, which ranged from 16 weeks to more than two years depending on temperature and stage. The predictions were consistent with reported survival times for I. ricinus and followed patterns reported for other ixodid ticks.