Treatments
We set up control, nutritional stress and mating delay treatment groups, each consisting of 96 adult female G. morsitans morsitans (Fig. 1), (see Supporting Information, S1 File). Because reducing the amount of haemoglobin in a bloodmeal results in lower pupal wet weights (Kabayo & Langley 1985), we chose to dilute red blood cells with serum to produce a low-quality diet for the nutritional stress group. Trials testing different ratios of red blood cells to serum showed that flies fed on c. 10% red blood cells produced lighter pupae but had similar survival, over a 50 day period, compared to flies fed on c. 45% red blood cells (S2 File). For the mating delay treatment, virgin females were kept in communal cages for three weeks post-emergence. Once mated, they were separated into individual cages, as described below. Virgin females continue to ovulate, but mature eggs eventually disintegrate (Ejezie & Davey 1977).