EFFECT OF THE LIFE-SPAN OF FEMALE GLOSSINA-PALPALIS-GAMBIENSIS ON THEWEIGHT AND SIZE OF ITS PROGENY

Pupae and teneral flies of Glossina palpalis gambiensis originating fr om three successive reproductive cycles were compared for their size a nd weight. In general, pupal weight and fly weight increased, whereas fly size, measured as wing vein length, decreased with the number of r eproductive cycles. The linear regression observed between weight and wing vein length of the fly demonstrated that, particularly for flies originating from the first and second larvipositions, small changes in wing vein length reflected substantial differences in weight. The res ults of these laboratory experiments were compared with some field dat a on Glossina morsitans from Zambia and related literature. The life s pan of the female tsetse, affecting the size of her progeny, could cla rify partially some of the field observed seasonal changes in size, wh ereas the correlation between fly size and weight could eventually exp lain the differential mortality of some size classes of tsetse flies. However, whether these laboratory observations can be extrapolated to the field has still to be confirmed.