Larvae of Culex mosquito (Photo: James Gathany, CDC)
RESEARCHERS from Bengal Engineering and Science University in Howrah,
West Bengal, claim to have found a cheap and effective way of
controlling mosquito breeding: water-soluble carbon nanoparticles
(wsCNPs).
In a paper published online on
September 12 in RSC Advances, the
researchers showed that when mosquito larvae ingested the nanoparticles,
their metabolism slowed down, they did not attain the pupal stage and
slowly died. The nanopowder could be of immense use in managing mosquito
larvae breeding sites.
The researchers used wood wool, readily available at any carpenter’s
workshop, to produce the powder. The process was similar to that of
making kajal. The researchers used two earthen pots—one to keep wood
wool and the other to cover it. The wood wool soot deposited on the
upper pot was scraped out and washed with acetone. The washed soot was
then air dried and oxidised with nitric acid to obtain wsCNPs.
The nanoparticle was tested on three types of mosquitoes–Anopheles,
Aedes and Culex. To monitor the growth and life cycle, optical
fluorescence microscope was used for imaging. One-day-old larvae were
cultured in three laboratory aquariums. The larvae were administered
variable doses of wsCNPs (0.5, 1, 2 and 3mg/l). It was found that a dose
of 3mg/l arrested the growth of mosquito beyond the larval stage and
after four weeks the larvae perished.
To test for toxicity, a year-long study was conducted on zebrafish
which were fed wsCNP-ingested dead mosquito larvae. No adverse effects
were reported. According to the authors, carbon nanomaterials do not get
absorbed by body tissues and may not possess the threat of entering the
food chain. In the US, carbon produced from burnt vegetables is
approved by the Food and Drug Administration and is used in a
homeopathic gripe water for infants.
“The idea of testing nano carbon for mosquito larva emerged as an
off-shoot of a previous work on cancer drug delivery. We were studying
this using fruit flies and mosquitoes when we observed this effect of
the nano particle,” says Sabyasachi Sarkar, chemist and co-author of the
study.
“The process of making 3mg of wsCNPs, excluding labour costs, came
close to less than a rupee. It took a couple of hours to wash the soot
with acetone and an overnight treatment with nitric acid. Overall the
material synthesis took three days,” Sarkar told Down To Earth.
David Sullivan, associate professor of microbiology and immunology at
Johns Hopkins Malaria Research Institute, US, says the study looks
promising enough to be tested in field. However, he also says that
further research is needed to assess if the water treated with wsCNPs is
fit for drinking after purification.
