A Mexican plant, widely available in India, is being promoted by National Centre for Disease Control (NCDC) as a handy weapon in the fight against mosquito-borne diseases. The leaf extracts of Agave americana, also known as century plant or Kamal cactus, has larvicidal properties, say NCDC scientists.
Simply put, when mosquitoes are exposed to the leaf extract of this plant at the larval stage (active, immature form), they die. “You can put the extracts in coolers and containers in which water has collected. Within 24 hours, the larvae will be dead,” Dr L J Kanhekar, joint director and head of the department of medical entomologist at NCDC, told TOI.
AC Dhariwal, NCDC director, added that municipal corporations are being advised to promote the use of such plants in the fight against vector-borne diseases through their information, education and communication (IEC) campaigns. “Unlike synthetic insecticides, the plant derived larvicides do not have any harmful effect on the environment or mankind,” he said.
In the past decade, vectorborne diseases have gone up significantly and so has the use of mosquito repellents.This has resulted in problems of resistance and side-effects.Scientists said use of natural repellents can help avoid these problems. “We are mulling over production of leaf ex tracts of Agave Americana in powdered or oil form for ease of use,” Dr Kanhekar said.
Padam Chand Saini, who owns a private nursery in northwest Delhi, said Agave Americana is sold between Rs 100 and Rs 400 depending on its size. “Few people know about their larvicidal properties. Last year, when there was a spurt in chikungunya cases, we got many customers asking for the plant,” he said.
Saini claimed that lemon grass and eucalyptus citriodora, two other varieties of potted plants, are also known for their mosquito-repellent properties.
Agave americana is a succulent desert plant native to Mexico. Many entomologists have reported that several other varieties of the Agave family have also exhibited larvicidal properties, for example Agave Angustofolia or Carribean Agave.”We need to think out of the box to fight against mosquito-borne diseases. It is causing public health crisis in many parts of the world, including India,” said a doctor.
This year, in spite of high temperature, Delhi has reported nearly 100 chikungunya and 40 dengue cases over the past six months. Officials fear the incidence may increase significantly post-monsoon.
Last year, 4,431 cases of dengue and 7,760 cases of chikungunya were reported in Delhi. Several people died due to the diseases. Experts said that early action against mosquito breeding is the only way to prevent outbreaks.