Factors affecting the acquisition of Plagiorchis noblei (Trematoda: Plagiorchiidae) metacercariae by larvae and pupae of Aedes aegypti in the laboratory.

When exposed to concentrations of less than one Plagiorchis noblei cercariae per cc of water, the acquisition of metacercariae by Aedes aegypti larvae increased significantly with each successive instar but declined precipitously upon pupation. Thus, 1st instar larvae acquired no metacercariae, whereas 4th instars had a mean abundance of 6.15: pupae only acquired a mean of 0.62 parasites. Parasite acquisition was largely a function of host size and activity. Other factors, such as grooming and feeding behavior, may affect the success of cercarial penetration and the distribution of metacercariae in the body of the insect host.