Mating age of Glossina austeni Newstead

Before removal from the emergence cage, 12.8% of 141 newly emerged females of Glossina austeni Newstead less than 24 h old were found on dissection to have been inseminated. Likewise, dissection of a sample of sterilised females destined for release showed that 5.43% of 2487 females had already been inseminated while still in the emergence cages. It was decided therefore to put female and male flies together in production cages from the day of emergence at a ratio of 1 male to 5 females and leave them to mature and mate in the cages. The females produced viable pupae of acceptable mean weight and desired quality with the proportion of A-Class pupae less than 10%. The number of pupae per initial female (PPIF) did not differ from pupae produced by pre-aged parent flies. It is now clear that there is no need to age female and male flies of G. austeni before mating. Parent flies of less than 1 day old put together in production cages from the day of emergence have been used for mass rearing G. austeni in the Tsetse and Trypanosomosis Research Institute (TTRI) colony to produce males for the eradication programme in Zanzibar since December 1995. This has substantially reduced the labour of fly production by removing the need to age flies and the need to chill and separate flies after mating.