The epidemiology of tsetse-transmitted trypanosomiasis depends, among other factors, on the proportion of infected flies in a tsetse population. A wide range of intrinsic and extrinsic factors seem to determine the ability of a tsetse fly to become infected and to transmit the parasite. In this paper, we investigated
the effect of nutritional stress of reproducing female Glossina morsitans morsitans on the susceptibility of
their offspring to trypanosomal infections. Adult female flies that were nutritionally stressed by feeding only once a week, produced pupae with a significant lower weight and offspring with a significant lower fat content aswell as a lower baseline immune peptide gene expression. Moreover, infection experiments showed that the emerging teneral flies were significantly more susceptible to a Trypanosoma congolense or Trypanosoma brucei brucei infection than flies emerging fromnon-starved adult females. These findings suggest that in the field, substantial nutritional stress of adult tsetse flies, as is often experienced during
the hot dry season, can increase significantly the vectorial capacity of the emerging teneral flies and thus result in an increased infection rate of the tsetse population.