Chitin-rich crab shell powder and nano-sized silver particles could be the key to a new environmentally friendly solution to stopping the spread of mosquitoes carrying diseases like malaria. (Wikicommons)Chitin-rich crab shell powder and nano-sized silver particles could be the key to a new environmentally friendly solution to stopping the spread of mosquitoes that could be carrying diseases like malaria.

Mosquitoes can be much more than just an annoyance at your summer BBQ. They can carry dangerous diseases like malaria, Zika virus, yellow fever and more. Even with years of research on the disease, malaria is still a threat all across the world, but especially so in Sub-Saharan Africa and Asia. There were 198 million cases of malaria and 548 malaria-related deaths. The World Health Organization says that one child in Africa dies per minute due to malaria. There have been many efforts to control mosquito populations and spread of this disease, but the mosquitoes just won’t quit.

The researchers were seeking a new solution to this problem, so the team at the National Taiwan Ocean University turned to chitosan or chitin. Chitin is a non-toxic natural substance that has been previously used in wound healing, manufacturing membrane water filters, and biodegradable food packaging coating. Chitin is found in animal tissues, like insect eggs or bird beaks. It can be chemically changed and is very strong and very cost-effective to use.

First, the team crushed and oven-dried the exoskeletons of hydrothermal vent crabs to extract the chitin and other minerals needed. The creamy-white filtrate was mixed with silver nitrate to obtain a solution of silver nanoparticles.

This solution was then sprayed over six water reservoirs at the National Institute of Communicable Disease Centre in India. It killed mosquito larvae and pupa very effectively. Its effect was best in the early stages of mosquito larvae development.

Researchers also tested this mixture with freshwater goldfish, which feed on mosquito larvae. The solution didn’t have any effect, positive or negative, on the fish. This shows that the mixture is environmentally friendly and non-toxic. It also stopped disease-causing bacterial species growing in this area.

"This research highlighted that chitosan-fabricated silver nanoparticles are easy to produce, stable over time, and 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 goldfishes," says Jiang-Shiou Hwang, who led the research team, "It also effectively inhibits important bacterial pathogens."

Researchers believe that the nanosize particles pass through the insect and into individual cells and interfere with various physiological processes that are part of the mosquito life cycle.

The paper was published in Springer’s journal Hydrobiologia.