NEW DELHI (Taiwan News) -- Scientists from Taiwan and India have made a spray from crab shells and silver nano particles that can curb the spread of malaria-carrying mosquitoes. Researchers from the National Taiwan Ocean University (NTOU) and the National Institute of Communicable Disease Center (NICDC) in Coimbatore had tested the environment-friendly solution successfully in India.
"The solution can be employed at low dosages to strongly reduce populations of the malaria vector, the Anopheles sundaicus mosquito without detrimental effects on the predation of natural mosquito enemies, such as goldfish," said Jiang-Shiou Hwang of the NTOU.
Researchers took chitosan or chitin, a non-toxic natural substance, found in animal tissues, such as the exoskeletons of arthropods, bird beaks and insect eggs, used in wound healing and in manufacturing biodegradable food package coating. Chitosan, that can easily be chemically changed, is quite strong and, because of its abundance in nature, is cost-effective too.
Researchers first crushed and oven-dried the exoskeletons of a number crabs before extracting chitin and other minerals. The subsequent creamy-white filtrate was then mixed with silver nitrate to obtain a brown-yellow solution of silver nano particles.
The solution, when sprayed over six water reservoirs at the NICDC even in small concentrate, it was found that it killed mosquito larvae and pupa quite effectively.
"This research highlighted that chitosan-fabricated silver nano particles are easy to produce, stable over time," Hwang said. "It had the greatest effect during the early stages of the mosquito larvae's development," researchers said.
The solution was also tested in conjunction with freshwater goldfish that fed on mosquito larvae. The nano particle solution did not have any effect on the fish, indicating that it is an environmentally friendly and non-toxic product.
It also inhibited the growth of disease-causing bacterial species such as Bacillus subtilis, Escherichia coli, Klebsiella pneumoniae and Proteus vulgaris.
The study was published in the journal Hydrobiologia.