A portable system for the in vitro feeding of tsetse flies

Abstract

A portable membrane feeder (PMF) was developed for infecting small numbers of laboratory Gtossina with trypanosomes and for their subsequent maintenance in relatively unsophisticated conditions. The feeder was directly heated by a resistor and incorporated a temperature transducer. These two components were connected to a detachable thermostat and a 12 V DC power source enabling the PMF to be employed in the field. The surface temperature reached that pre-set (±0·2°C) within ten to 20 minutes. The feeder complete with silicone membrane was routinely dry-heat disinfected before use.

Tsetse infected from the PMF successfully transmitted two stocks of the subgenus Trypatwzoon to mice, although data were inadequate for infection rates to be compared with those infected from live mice. Significantly more (P<0·005) three to 20-hour-old teneral flies took a first feed from the PMF (74%) than from live mice (50%). Trypanosome motility, occurrence of deformed and agglutinated forms, and loss of infectivity to mice of infected blood in the PMF were used as indicators of deterioration. Results suggested that a reasonable estimate of infective life of a blood meal in the PMF was 30–40 minutes. Dead flies were found infected with Pseudomonas, Proteus and Bacillus which may have originated from mice on which flies were fed. Contamination of blood in the PMF with bacteria was not important.