Activity, ageing and penetration of hookworm larvae

Abstract

Lipid levels of infective larvae of Ancylostoma tubaeforme are reduced and their behavioural activity declines with age. We have measured behavioural activity using the percentage active, rate of activity, and the percentage of larvae able to penetrate a membrane. Neostigmine bromide, a cholinergic drug, increased larval activity in all tests. Larvae, stored at 4 and 10 °C and in hypertonic saline, were inactive but consumed lipid. When returned to isotonic saline at 26 °C, these larvae were no more active than those at 26 °C throughout. We found no evidence that such inactive larvae had entered a state of quiescence. All our results, and those of other workers, have been used to emphasize that larval ageing is related directly to decreased metabolic rates, and not primarily to lipid levels.