Bloodmeal microfilariae density and the uptake and establishment of Wuchereria bancrofti infections in Culex quinquefasciatus and Aedes aegypti

The relationship between ingestion of microfilariae (mf), production of inf ective larvae (L3) and mf density in human blood has been suggested as an i mportant determinant in the transmission dynamics of lymphatic filariasis. Here we assess the role of these factors in determining the competence of a natural vector Culex quinquefasciatus and a non vector Aedes aegypti to tr ansmit Wuchereria bancrofti. Mosquitoes were infected via a membrane feedin g procedure. Both mosquito species ingested more than the expected number o f microfilariae (concentrating factor was 1.28 and 1.81 for Cx. quinquefasc iatus and Ae. aegypti, respectively) but Cx. quinquefasciatus ingested arou nd twice as many mf as Ae. aegypti because its larger blood meal size. Ae. aegypti showed a faster mf migration capacity compared to Cx. quinquefascia tus but did not allow parasite maturation under our experimental conditions . Similar proportions of melanized parasites were observed in Ae. aegypti ( 2.4%) and Cx. quinquefasciatus (2.1%). However, no relationship between rte of infection and melanization was observed. We conclude that in these cond itions physiological factors governing parasite development in the thorax m ay be more important in limiting vectorial competence than the density of m f ingested.