Studies on the Bionomics of Aëdes aegypti (L.) in its Natural Habitats in a Coastal Region of Kenya

Abstract

Studies have been made of the bionomics and ecology of Aëdes aegypti (L.) entirely under natural conditions and in its natural habitats on the Kenya coast.Development from egg to adult under conditions approximating as nearly as possible to those in nature took a minimum of eight days and a maximum of twenty-five.Males were in excess of females, in the proportion seventeen to ten, from eggs hatched in natural breeding places.Although the mosquito may be able to propagate in houses, adults from outside habitually enter premises. If this entry is for egg-laying, then eradication by domestic larval control alone, although reputedly achieved elsewhere, is not possible under conditions obtaining in the coastal belt of Kenya. Windowtrap captures, however, indicate that the entry may not be for the purpose of egg-laying.The seasonal reduction of both larvae and adults in houses during the hot, dry months of February and March is attributed to a combination of the absence of breeding places outside and the shorter life span of the mosquito at this time.It is shown that both sexes enter and leave native huts throughout the 24-hour period, but the movement is confined almost wholly to the hours of daylight. The flight from houses is much reduced in the cool months (July and August). This corresponds with the season when most enter.

Genes and Odors Underlying the Recent Evolution of Mosquito Preference for Humans

“…References for subsp. formosus and mixed populations (bottom row): Entebbe, Uganda [7]; Mombasa, Kenya [48]; Ganda, Kenya [7]. (B) An early example of host attraction and preference assays from 1973 in a two-port olfactometer [8].…”

Sampling Adults by Animal Bait Catches and by Animal-Baited Traps

“…Roberts & Scanlon (1975), however, failed to observe any obvious depletion effect with nocturnal species such as Culex salinarius and Aedes fulvus. An initial high catch was also reported in Aedes aegypti in catches performed both outdoors and in huts in Kenya (Teesdale, 1955). Colless (1956Colless ( , 1957 considered that mosquitoes arrived at bait by a process of random wandering, or at least by a process not directly orientated to the bait.…”

“…Because of such opportunistic feeding it may be necessary to perform a preliminary bait catch for about 30 min, or even 1 hr, to clear an area of hungry unfed mosquitoes before diel biting cycles can be studied (Service, 1969a; Teesdale, 1955). In England, however, Renshaw (1991) believed the high initial catch of Aedes can tans was due to hungry females following her through a wood to the catch site.…”

“…In Uganda, Henderson et al (1972) employed mosquito catchers to walk at least 25 yd then stop and catch for 10 min, after which they proceeded for another 25 yd or more. In Kenya more adults of Aedes aegypti and other Aedes species were caught by catchers slowly walking through the bush than in stationary catches (Teesdale, 1955(Teesdale, , 1959.…”

“…Similarly Teesdale (1955) caught considerably fewer mosquitoes in window traps used as entry rather than exit traps, but in Nigeria entry traps fitted to village huts caught substantial numbers of Anopheles gambiae, Anopheles Junestus and even Anopheles nili (Service, 1963). They were very useful in showing that about 24, 16 and 52% respectively of these three species entered huts as blood-fed individuals.…”