Bionomics of anopheline mosquitoes in the Faiyoum Governorate, Egypt, in relation to transmission and control of malaria

ABSTRACT

The biology and ecology of the two main malaria vectors, Anopheles pharoensis and Anopheles multicolor, were studied for two successive seasons [1975 -1976] in the Faiyoum Governorate. The different techniques employed in sampling the biting populations of these anophelines included Monks wood light traps; bed-net traps, human and animal baits. Results of this study indicated Anopheles pharoensis Theob. [1] Field investigations 1. This anopheline is present in different localities of the Faiyoum Govemorate, especially in Senouris, 9 km to the north east of Faiyoum City. 2. Its breeding water in Senouris, had a pH value that ranged from 7.35 - 7.80 [1600 samples examined]. Its salinity ranged from 0.33 - 0.74 gm NaCl / litre [1600 samples examined]. 3. Adult females of this species are zoophilic rather than anthropophilic, exophagic and exophilic. 4. Out of 287 dissected specimens collected from Mensheit Haifa during the month of September 1975; one salivary gland infection was recorded. Two positive stomach infections in Senouris out of 590 specimens dissected during the month of August 1976. 5. Monks wood light traps proved very unsuccessful in collecting adults of this mosquito. 6. The highest biting activity of females of this species was encountered at El-Nazlah and Mensheit Haifa during October; and during August-September in Senouris. 7. Two biting peaks were evident from sunset to sunrise [i] two hours after sunset and [ii] two hours before sunrise, [iii] midnight, [during some night observations]. [2] Breeding in the laboratory Breeding of the different developmental stages of An. pharoensis was carried out successfully at a temperature of 27 +/- 0.5°C and a relative humidity of 85 +/- 5% in a thermostatically controlled walk-in incubator with adjustable temperature, humidity and light. Anopheles multicolor Camb[1] Field investigations 1. This mosquito was found in various localities of the Faiyoum Governorate, especially in the Valley of El-Nazleh. 2. Its larval breeding waters in El-Nazlah had a pH value that ranged from 7.41 - 7.86; its salinty ranged from 11.15 - 23.56 gm NaCI / litre. However, its larval breeding waters in Mensheit Haifa had a pH value that ranged from 7.26 - 8.07 [1600 samples examined]; while its salinity ranged from 2.82 - 27.64 gm NaCl / litre [1600 samples examined]. 3. Adult females of this species are zoophilic rather than anthropophilic; exophagic and exophilic. 4. No salivary gland or stomach infections were found in all dissected specimens [35 dissected]. 5. Monks wood light traps proved very unsuccessful in sampling adults of this mosquito. 6. The highest biting activity of this species in both El-Nazlah and Mensheit Haifa was during September-October. 7. Females of this species had two evident peaks of biting at night [i] at sunset and [ii] midnight