Gametocyte production and fertilisation were not different from wild type. During the first 12h of in vitro culture, mutant zygotes differentiated into morphologically advanced ookinetes (stage IV-VI) in similar numbers as wild type. In cultures of wild ookinetes, mature ookinete forms continued to accumulate in in vitro culture, reaching 60% of all macrogamete-derived parasites by 24h, the remainder presumably being unfertilised macrogametes. In contrast, all the morphologically mature ookinetes in the early cultures (12h) of the mutant were replaced successively by stumpy and round forms and at 24h, hardly any typically shaped ookinetes were present. Motility of ookinetes was affected (see 'Additional information'). The mutant ookinetes had a greatly reduced capacity to develop into oocysts; oocyst numbers on the mosquito midgut epithelium were reduced by >94%.

The mutant ookinetes had a greatly reduced capacity to develop into oocysts; oocyst numbers on the mosquito midgut epithelium were reduced by >94%.