Some factors affecting eclosion ofGlossina morsitansWestw. from pupae

Abstract

Observations on biological variablity of pupae ofG. morsitansWestw. collected in the field, and effect on eclosion of the adult fly due to temperature, light and gamma-radiation are reported.The homogeneity of eclosion from wild pupae varied during the year owing to variations in pupal viability. Emergence was lower in the warmer months September to December than in the cooler ones, May to August, and in one season low eclosion rates were connected with a high proportion of runts, although another analysis revealed no correlation.Gamma-radiation redused eclosin by killing all pupae treated during their first ten days after larviposition. MOrtality of male pupae was increased by irradiation between the 15th and 13th day of pupal life, while eclosion was apparently normal with treatments given between the 16th and 29th day. Weight losses indicated that five- to ten-day-old pupae possibly did not die before the 30th day after larviposition while younger pupae containing fourth-instar larvae at the time of treatment were killed either immediately or by the 15th day.Diurnal emergence from wild pupae in the laboratory showed a peak during the afternoon (1400–1730 hr.) which was not affected by light or gamma-radiation. In the field, eclosion occurred primarily between 15° and 27°C. and was apparently inhibited by higher and lower temperatures. Relative humidity did not appear to be involved in the timing of emergence.