Facultative blood-feeding by nulliparous autogenous Egyptian aedes caspius pallas [diptera: culicidae]

ABSTRACT

Facultative blood-feeding, in which nulliparous autogenous Aedes caspius females imbibed blood from a human host before laying their first egg batch, was compared in various geographic populations under laboratory conditions. It accounted for about 39% in the populations tested [range 27 - 54%]. Temporal blood-feeding activity studies demonstrated that nulliparous autogenous females were liable to ingest blood from 1 to 6 days postemergence, although most females elected to feed when 2 or 3 days old. Ovarian development, determined at the time of blood-feeding, varied from Christopher's stage II B to stage V indicating that vitellogenesis did not inhibit blood-feeding and that the degree of maturation of the ovaries was not a limiting factor to blood-feeding of autogenous females. However significant population differences regarding ovarian stage at the time of blood ingestion were observed. Most autogenous females were half blood-fed regardless the degree of maturation of their follicles. It seems likely that many nulliparous autogenous Ae. caspius will not delay their initial blood meal until they have laid their autogenous egg batch, this would result in early repeated host seeking attempts by these mosquitoes, thereby increasing their vectorial capacity