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Anopheles (Cellia) aconitus Dönitz, 1902

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Habitats

Anopheles aconitus can be found from sea level to upland hill zones at higher altitudes (600-800 m), but is generally restricted to below 1000 m. Depending on the season (rainfall and/or agricultural cycle), it can be a very abundant mosquito. Larvae are frequently found in open country near foothills and forest fringes with rice fields (active and fallow), various shallow pools (rock, stream, seepage, flood) and slow moving streams with grassy margins. Both coastal plain and upland rice fields (young and older plants) are particularly favoured habitats, especially when plants are closer to maturity and greater than 1.5 m in height. Larvae can also be found in abundance in fallow rice fields and rain-fed pools in dry fields. Aquatic habitats are almost exclusively clear (non-polluted but sometimes turbid or slightly cloudy), stagnant or slow-flowing fresh water, mostly sun-exposed, and only on occasion are larvae found in small running (lotic) streams. In most cases, common larval habitats contain various floating plants (e.g. water hyacinth) and algae. Other natural and human-made larval sites include lakes, swamps, marshes, flooded grassland, shallow ponds, ground depressions, pools in rocks, creeks and river beds, irrigation channels, fish ponds, roadside storm water drains, open ditches and tanks (reservoirs) with grassy margins. On rare occasions this species has been found in wells, borrow pits, wheel ruts, hoof prints or small container habitats. Adult mosquitoes can be found throughout the year in many localities but often show strong seasonal population peaks that coincide with the time of rice harvest.

Rice fields, Indonesia
Rice fields, Indonesia

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Resting and feeding preferences

Females are primarily zoophilic, sometimes strongly so, but when larger animals (e.g. bovids) are scarce, they will feed on humans as an alternative host. Females will feed on humans both inside and outside houses and in varying proportions, depending on location, generally with no strong preference reported. Feeding can occur throughout the evening, typically beginning at dusk, with the majority of females feeding on humans before midnight. In Timor-Leste, peak feeding has been reported to commonly occur during the first hour of the evening continuing only sporadically for the remainder of the night. Variation in feeding habits has been noted by location (e.g. coastal vs upland) and season. Some blood-fed females will rest indoors by day, but overall this species is considered strongly exophilic throughout its range. Natural outdoor adult resting places include steep, shaded stream banks, irrigation ditches and low shaded undergrowth. Common human-made resting sites are found in and around animal shelters.

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Vectorial capacity

Throughout much of its geographical range Anopheles aconitus is considered a secondary (incidental) malaria vector, however, under ideal conditions this species can play a major role in malaria transmission. This species has been incriminated as a secondary, but important, regional vector of malarial parasites in Thailand and Bangladesh. In Indonesia, it is considered a primary, but focal, vector throughout much of Java and areas of Sumatra, especially in locations with intense rice cultivation. It appears to play no, or only a very minor, role as a vector in Sulawesi, Kalimantan and the Lesser Sunda island group (e.g. Bali, Lombok, etc.). In general, vectorial capacity can be increased by large seasonal or continuous biting densities. Even in areas where An. aconitus is still regarded as a primary vector (e.g. upland areas of Java and Sumatra), its epidemiological importance appears density dependent (both mosquito and human) and is likely to be influenced by the number of cattle or buffalo present in relation to humans. During seasonal peak periods when large numbers of adults are in close proximity to more concentrated human populations, especially when fewer cattle or other non-human hosts are available, its medical importance can dramatically increase. The close association of An. aconitus with rice cultivation practices and periodic adult population peaks has been linked to increased malaria transmission in central Java during the two main periods of harvest (March-April and August-September). In fact, in the early decades of malaria control in Indonesia, knowledge of the close relationship of this species with rice and irrigation schemes lead to the development of successful, non-chemical, vector control practices using environmental and mechanical interventions such as intermittent irrigation and drainage schemes.

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Further details and the sources for this text can be found in

Sinka, M.E., Bangs, M.J, Manguin, S., Chareonviriyaphap, T., Patil, A.P., Temperley, W.H., Gething, P.W., Elyazar, I.R.F., Kabaria, C.W., Harbach, R.E. and Hay, S.I. (2011). The dominant Anopheles vectors of human malaria in the Asia-Pacific region: occurrence data, distribution maps and bionomic précis. Parasites and Vectors 4: 89

This text has come from multiple sources which are all listed in the above paper