doi:10.1038/nindia.2017.59 Published online 26 May 2017
Scientists have developed a non-toxic mixture of crushed crab shells and silver nanoparticles that can kill larvae and pupa of malaria-spreading mosquitoes. The mixture could help halt the spread of disease-carrying mosquitoes.
Researchers from the National Institute of Communicable Disease Centre in Coimbatore, India along with colleagues from Taiwan, Saudi Arabia and Italy used chitosan, a non-toxic biomaterial derived from crab and lobster shells, to make the mixture. Chitosan has earlier been used in wound healing, membrane water filters and biodegradable food package coating.
Chitosan-fabricated silver nanoparticles (Ch-AgNP) were found to be highly toxic to Anopheles sundaicus, a malaria vector. In laboratory experiments, the mixture showed 100% larval reduction in 72 hours. The researchers then sprayed the mixture over six water reservoirs. "Even in small concentrates, it killed mosquito larvae and pupa quite effectively," they report.
The nanosized particles pass through the insect cuticles into individual cells and interfere with various physiological processes in the mosquito's life cycle, the researchers say. The solution did not have any detrimental effect on goldfish (Carassiu auratus), which is a natural predator of mosquito larvae "indicating that it is an environmentally friendly and non-toxic product." The mixture also inhibited the growth of disease-causing bacterial species such as Bacillus subtilis, Escherichia coli, Klebsiella pneumoniae and Proteus vulgaris.
Ch–AgNP may offer a novel and safer control strategy against A. sundaicus mosquito vectors, as well as against Gram-negative and Gram-positive pathogenic bacteria. The finding also suggests that chitosan-based products "could potentially be less harmful to non-target insects compared to conventional insecticides.
1. Murugan, K. et al. Chitosan-fabricated Ag nanoparticles and larvivorous fishes: a novel route to control the coastal malaria vector Anopheles sundaicus? Hydrobiologia (2017) doi: 10.1007/s10750-017-3196-1