International day of mosquitoes

The days of mosquito-borne diseases might be numbered ….

August 20^th was the international day of mosquitoes. These small insects might be a nuisance for us in northern Ontario, but in other parts of the world they affect the lives of millions of people by transmitting some of the most deadly diseases. With this in mind, I want to share some of the current ongoing mosquito research, which aims to decrease their impact on human populations.

New type of mosquito trap

Mosquitoes require standing water in order to reproduce. Females will lay eggs in water and the immature larvae will complete their aquatic lifecycle by consuming algae and bacteria. In a matter of days or weeks (depending on the species), the larvae will emerge from the water as an adult. Many mosquito eradication programs have focused on killing the adults with pesticides or trapping them with nets. The problems with these methods are two-fold: i) pesticides can have negative impacts on the environment and ii) trapping adults does not solve the problem that adult mosquitoes are already present to transmit diseases. Scientists have now focused on methods of removing mosquitoes as larvae before they become adults. A Canadian researcher, Dr. Gerardo Ulibarri, developed a larval mosquito trap. This automated trap (Green Strike) is essentially a tub with water in which a specialized concoction is added to attract female mosquitoes. The females lay eggs within the water of the tub and the tub automatically removes the larvae before they mature into adults. Although this trap is quite effective, it is too costly to be sold and used in developing countries.

Dr. Ulibarri continued his work in developing a cheaper trap. He developed a trap that uses materials readily available and can be made quite easily. This new type of trap called the “ovillanta” is made from old car tires and PVC piping. Once assembled, users only have to add water and a yeast/bacteria concoction to it to attract female mosquitoes. Users have to regularly remove the mosquito eggs and larvae by filtering the concoction solution.   Dr. Ulibarri reported that these “ovillanta” appear to function better than “tub” mosquito traps in attracting female mosquitoes. The main advantage with these “ovillanta” is that they are cheap to make and maintain. These traps could effectively control mosquito populations, without the use of pesticides! Learn more about the “ovillanta” here.

Better mosquito repellent

We know that certain repellents such as DEET work effectively in repelling mosquitoes. But scientists do not know exactly how these repellents work. Very little research has been done to determine what exactly happens physically to the mosquitoes when repellents are applied. Do repellents “mask” the smell of people or do they make a person smell repugnant to the mosquito?

Scientists are currently conducting research to determine which chemicals can affect the ability of mosquitoes to detect humans. One chemical called ethyl pyruvate shows some promise.   When this chemical is applied to sensors found on the head of a female mosquito (since only female mosquitoes bite), the neural activity from the sensors decreases dramatically. In other words, ethyl pyruvate decreases the capacity of the mosquito to sense the carbon dioxide breathed out by people. Unfortunately, ethyl pyruvate is not a viable option as a repellent due its high cost of production. This research is providing valuable information on how mosquitoes detect humans. Hopefully in the near future, scientists will develop new and more effective repellents. Learn more about this exciting mosquito research here.

Genetically modified mosquitoes

With the advent of genetic engineering, new techniques are being developed to combat mosquito borne diseases. One such application is using genetically modified male mosquitoes to combat the spread of Zika virus. Offspring from these males will not live long enough to reproduce.   In essence, the genetically modified males help to reduce mosquito populations and the corresponding spread of Zika virus.

Another novel method involves using a new genetic technique called CRISPR.   CRISPR stands for “Clustered regularly interspaced short palindromic repeats” and it was discovered within certain types of bacteria. This genetic technique allows the incorporation of new genetic information with the DNA of an organism and that genetic information can be transmitted to future generations. This technique is currently being examined to eradicate malaria. Malaria is caused by a parasite, which infects the blood and is estimated to affect over 200 million people per year. Malaria is transmitted in the saliva of an infected mosquito as it bites for a blood meal. Research on these genetically modified mosquitoes has shown that they are unable to transmit the malarial parasite. Furthermore, most offspring from these mosquitoes “retain” this ability and they too cannot infect people. The advantage of this technique is that the genetic trait is maintained within the mosquito population without the need of human intervention.

Using genetic techniques to control mosquito borne diseases is an exciting new field. With these techniques there is no need to use poisonous chemicals to control mosquito populations. Potentially, several mosquito borne diseases could be effectively “wiped out” in a short period of time. Learn more about these techniques here.