Normal numbers of gametocytes, gametes, zygotes and mature ookinetes are formed. In Giemsa stained smears the morphology of mutant ookinetes is comparable to that of wild type ookinetes. Ookinetes have a reduced (30-90%) capacity to produce oocysts in A. stephensi mosquitoes(see phenotype 'Oocysts').

When fed to A. stephensi mosquitoes, significant reductions in oocyst numbers of between 30 and 90% were obtained with the mutant parasites. The oocyst formed, produced normal numbers of sporozoites, that were infectious to the mammalian host.