Fisheries experts of Bangladesh Agricultural University have suggested introduction of "biological control of mosquito" by releasing small fishes of local species into the breeding sites.

This low-cost method is simple and environment-friendly, they said.

In a recent virtual press conference, Dr Harunur Rashid, a professor of Department of Fisheries Management under Faculty of Fisheries at BAU, talked about his research on such method. Dean (acting) Prof Md Abul Mansur presided over the programme.

Dr Rashid said he started his research -- "Biological Control of Mosquito Larvae Grown in Waterlogged Environment using Larvivorous Fishes and Comparison of Efficiency between Native and Exotic Fish Species" -- in Chottagram in 2017.

Dr Rashid said he used two exotic varieties -- guppy and mosquitofish -- and three local species -- khalisa, darkina and dhani of larvicidal nature.

It was found that the local fishes are more efficient in consuming mosquito larvae living in the drain water; and of them, khalisa fish is the best performer. The artificial breeding of the country varieties is also easy, said Dr Rashid.

World Health Organization (WHO) also suggested use of small local species in mosquito control, he said.

In many Asian countries like Vietnam, Laos, Malaysia, Singapore, Hong Kong and India, small local fishes are used as part of integrated initiatives to check mosquito menace, said the researcher.

Under "Integrated Vector-borne Disease Control Programme", fishes are released in drains and stagnant waterbodies in the cities of those countries and they have got good results. This method has also been initiated in rural areas, said the professor.

Dr Rashid said some seven years ago, this guppy and mosquitofish were released in the drains of Dhaka and Chottagram cities on experimental basis.

During the initial stage of his research, he found they were breeding in the drain water.

The authorities can release the local species in drains and waterlogged places in the city to contain mosquito menace. The BAU fisheries scientists will also provide support in this regard.

The experts also said alteration of natural habitats in the terrestrial ecosystem, deforestation, urbanisation, dam constructions etc are resulting in increasing waterlogging problems in many Asian countries including Bangladesh. One common public health concern with waterlogging is rise in mosquito population in waterlogged areas.

Together with other management and pesticide control measures, biological control is found to be one of the most effective and convenient methods, they said.