Bionomics of Anopheles maculatus complex and their role in malaria transmission in Thailand.

The bionomics of Anopheles maculatus complex and its role in malaria transmission were conducted in Pakchong and Sadao districts, Nakhon Ratchasima and Songkhla provinces, respectively, from January 1984 to July 1985. In Pakchong, An. maculatus species A was the most dominant species, followed by species B form F and species C which was rare. The densities of species A and species B form F were high between July and November, with their peaks in October. Biting activities of both species occurred through out the night, with a major peak during the first quarter of the night on all seasons. In Sadao, only An. maculatus species B form E was detected with peak densities between February and June. Biting activities of this species varied according to seasons. The prevalence of mosquitoes was influenced by monthly rainfall, relative humidity and air-temperature. All species of female An. maculatus complex studied prefered to feed on animal rather than on human, and tended to bit human more outdoors than indoors, and thus exhibiting a zoophilic and exophagic behaviour. Life expectancies of An. maculatus species A ranged from 1.6 to 6.6 days, species B form F from 1.1 to 8.1 days, and species B form E from 0.7 to 21.2 days. The natural malaria infection rate was very low. Out of 4,430 guts dissected, only 0.23% were found infected with oocysts. There were no sporozoites detected in the 4,472 dissected salivary glands.

Bionomics of Anopheles minimus and its role in malaria transmission in Thailand.

The bionomics of Anopheles minimus, one of the main malaria vectors in Thailand, were conducted in Pakchong district, Nakhon Ratchasima province, from January 1984 to June 1985. The prevalence of An. minimus was influenced by monthly rainfall, relative humidity, temperature and wind velocity, with a major peak of density from September to November. An. minimus preferred to feed on animal rather than on human, tended to bite human more outdoors than indoors, and thus exhibiting zoophilic and exophilic behaviour. The biting activity of the mosquitoes on animal exhibited high densities throughout the night in all seasons, whereas on human they tended to be an early evening biter in the dry cool season, and early morning biter in the wet season, and thus increasing the chance of man-vector contact. The life expectancy of An. minimus varied from month to month, ranging from 2.7 to 11.5 days, with the longest longevity during the dry cool season. The natural malaria infection rate of this species was very low. Out of 1,518 dissected guts, only 0.4% were found infected with oocysts. There were no sporozoites detected in the 1,560 dissected salivary glands.