Fumigation ‘not a solution’

GCU Zoology Dept head says sprays result in mosquitoes developing resistance to insecticides.

LAHORE:

Dengue mosquitoes can be controlled effectively by biological methods as use of insecticide was not a sustainable way of eliminating the mosquito, Government College University Lahore Zoology Department chairwoman Prof Dr Nusrat Jahan said on Thursday.

She was speaking at a seminar on Prevention and Control of Dengue Fever.

She said fumigation of neighbourhoods should be considered an emergency measure only and not be taken as the standard way of eliminating mosquitoes known for spreading the virus. She said mosquitoes could develop immunity to insecticides and chemicals used in fumigation from exposure over a period of time.

She said several predatory insects and other invertebrates were found to feed on aedes mosquito and their eggs. Biological control of mosquitoes, she said, was more effective and caused little risk to humans, wildlife and the environment.

The useful predators included copepods, parasitic nematodes, larvivorous fish and microbial entomopathogens including bacillus thuringiensis.

Prof Jahan said different formulations of biological insecticides were commercially available and had become the preferred mode of preventing a dengue outbreak in some other countries coping with the disease.

She said a mixture of small crustaceans (known as copepods) and an enzyme called Bti was one of the most effective biological methods to prevent dengue fever. She said the mixture was found to have eliminated all first stage aedes larvae present in large water containers.

Another method, she said, was the setting up of ovitraps. An ovitrap can be made by a filling a black plastic container with water and adding a thin paddle of wood in it. Chemical as well as biological insecticides can be added to the water to kill the mosquitoes.

The GCU chief zoologist said the department was currently conducting research on detecting dengue viruses in the vector mosquitoes.

She said further research in medical entomology could be helpful in developing effective strategies for managing the population of these mosquitoes.

She said over the last two decades the number of dengue fever cases across the globe had increased four times.

The first outbreak of the disease in Pakistan was reported from Karachi in 1994, she added.

She said people should make it a habit to keeping water containers covered and clean. She said discarded containers as well as obsolete tyres should be disposed of so that they did not provide a breeding site to mosquitoes. She stressed effective and timely disposal of waste.

GCU Vice Chancellor Prof Dr Muhammad Khaleequr Rahman said that the university would support the Zoology Department in continuing research on prevention of dengue fever.

He said the university had arranged fumigation of the premises as well as the surrounding areas. He said an awareness raising campaign was also underway.

Published in The Express Tribune, September 30^th, 2011.