Comparison of water ingestion between black flies (Simuliidae) and a mosquito (Aedes aegypti; Culicidae) using radiolabelled glucose

Abstract

Ingestion of water by larvae of the black flies Simulium verecundum, Prosimulium mixtum/fuscum and Cnephnia dacotensis and by larvae of the mosquito Aedes aegypti was studied with radiolabelled glucose as a tracer. Extremely low (≤ 200 dpm/3 h) radiolabel uptake occurred in the black flies species, while Aedes aegypti, a species that is known to drink, had high radiolabel counts (> 6000 dpm/3 h). Radiolabel uptake by S. verecundum did not change for larvae fed in absence of current or with plugged mouthparts versus normal larvae. Radiolabel uptake by Aedes aegypti larvae with plugged mouthparts was < 3% of radiolabel uptake in normal larvae. Aedes aegypti was able to ingest the soluble glucose. Simulium verecundum, Prosimulium mixtum/fuscum and Cnephia dacotensis were unable to ingest the soluble sugar. The rationale for this difference is in the different filter-feeding mechanism of Culicidae and Simuliidae.