Calculations of the productivity of Glossina austeni Newst. maintained on goats and on lop-eared rabbits.

The productivity of Glossina austeni Newst., maintained on lop-eared rabbits, has been calculated by Jordan & Curtis (1968a). The distinction was made between colonies in the " expanding phase ", when all female offspring produced by the colony are added to the breeding stock and growth is exponential, and the "stationary phase", when sufficient offspring are retained to keep the colony at constant size and the remainder used for some purpose such as sterilisation and release. The calculations were not based on direct observations on colonies in the expanding and stationary phases but on data for the female life-table and age-specific fecundity. For the expanding phase, rm, the innate capacity for increase in numbers (Andrewartha & Birch, 1954), was calculated. Hence the expected rate of increase of an expanding colony could be determined. For the stationary phase, productivity was calculated in terms of the weekly output of disposable pupae or young adult males. Since the performance of rabbit-fed G. austeni was determined, modifications have been made in the method of pupal maintenance employed at this laboratory which have resulted in an improved emergence rate (Nash et ah, 1968). One implication of this is that the values obtained by Jordan & Curtis (1968a) are underestimates of the performance now obtainable with rabbit-fed G. austeni. In this paper, the new data for emergence rate are employed in the calculation of the current productivity of goat-fed females, and in a recalculation of the rabbit performance; the significance of the results is discussed.