Comparative exsheathment of microfilariae of Wuchereria bancrofti in certain mosquito species.

The exsheathment of ingested microfilariae (mf) of Wuchereria bancrofti in their vector Culex. (Cx.) pipiens and in a refractory mosquito species Aedes (Ae.) caspius was assessed. No exsheathed mf were encountered in the mid gut of tested mosquitoes, while they were observed in abdomen and thoracic muscles. All exsheathed mf migrated from the mid gut of both tested species. The lowest percentage of ingested mf was recorded in the mid gut of Cx. pipiens and the thoracic muscles of Ae. caspius one day post feeding. On the other hand, 94.2% out of the exsheathed mf reached the thoracic region of Cx. pipiens and one-tenth of this proportion was observed in the thorax of Ae. caspius. Failure of a large percentage of mf to exsheath after being ingested in the Ae. caspius indicates inefficient vector ability to support the filarial development to the infective stage.