Mosquitoes are a part of life here in Malaysia. They’re in every tropical country. It’s bad enough that their buzzing sound is irritating and their bites cause your skin to become itchy. What’s worse is that sometimes, those bites can lead to dengue fever.
This is a common enough occurrence; almost everyone knows someone who has had dengue fever before — a family member, friend, neighbour. It’s a pretty horrible thing and can even lead to death.
We can try to ward off mosquitoes using mosquito coils or mosquito screens on our windows. But it’s hard to completely avoid mosquitoes when you live in a tropical country. Fogging helps to an extent but after a while, mosquitoes return.
There has to be a better solution. The idea of introducing “modified” male mosquitoes into the wild that would result in non-viable offspring is one way that could be very effective. It’s not actually a new idea and has been tried overseas and even here in Malaysia.
Brazil experimented with genetically-modified mosquitoes in response to the Zika virus that emerged in 2015. It did so with male mosquitoes developed by a company called Oxitec from the UK. When those males mated with female mosquitoes in the wild, their offspring wouldn’t be viable.
This concept is sound but many people — rightly or wrongly — have a negative reaction against anything that’s genetically-modified, be it plants or insects. When Oxitec tried to do a similar test with GMO mosquitoes in Florida, the community there voted against it. We’ve also had some trials with modified mosquitoes in Malaysia as early as 2010 but in 2015, the government decided against rolling out this plan.
The same concept, albeit with a new twist, has just been approved by the US Environmental Protection Agency (EPA) and it could very well be the solution to the mosquito woes of many tropical countries, including Malaysia.
INTERESTING BACTERIA
Earlier this month, the EPA approved the use of male mosquitoes infected with bacteria called Wolbachia pipientis to be used as a method to kill off the Asian tiger mosquito (Aedes albopictus), which is known for spreading diseases like dengue and Zika.
The Wolbachia bacteria is apparently common in the insect world but they’re harmless to animals and humans. When a male mosquito infected with it mates with a female mosquito from the wild, the fertilised eggs won’t hatch. As more of these bacteria-infected males are released, the wild population of Aedes mosquitoes should theoretically decrease.
This bacteria is interesting because it doesn’t just live inside the insects that it infects, it lives inside their cells, which means that it’s passed down from mother to offspring, rendering them unviable because the paternal chromosomes do not form properly
It’s worth noting that male mosquitoes don’t bite humans. It’s only the females that do so as they need blood to nourish their eggs. So the release of these infected male mosquitoes will not result in more mosquito bites.
The fact that MosquitoMate’s killer mosquito is not genetically-modified works in its favour. While Oxitec’s genetically-modified mosquito was rejected in Florida, MosquitoMate has already successfully conducted several tests there as there was no public resistance to it.
Malaysia is also in the midst of running some trials involving Wolbachia-infected male mosquitoes. Earlier this year it was reported that tests would be conducted in Aedes-prone areas in Shah Alam and Keramat.
It would literally be years before these trials are concluded. According to press reports, the Health Ministry will do a final evaluation at the end of 2020 before deciding whether to roll out this programme to the rest of the country.
ADVANTAGES AND LIMITATIONS
There’s actually another non-GMO approach that could be adopted to rid an area of mosquitoes. And it has already been tested in this country. Three years ago, toxorhynchites (toxo) mosquitoes were released into the Subang Jaya area in an effort to curb mosquitoes from breeding.
The toxo mosquito is known for eating other mosquito larvae and thus could help to decrease the Aedes population by eating its larvae. The great thing about toxo mosquitoes is that they feed on plant nectar, not blood, and thus will not bite humans.
This all sounds pretty good except that the trials weren’t that successful due to the environmental condition in Subang Jaya, which is something of a concrete jungle. Apparently, for the toxo mosquito to thrive, it needs to have lots of vegetation — with trees and bushes around. That makes it unsuitable for urban areas. Hence, the Wolbachia approach is probably better suited for cities.
That said, there are also some limitations to this approach. MosquitoMate’s lab workers currently separate the males from the females manually. This process is time consuming and obviously doesn’t allow for scaling up production.
That’s okay if you’re just producing mosquitoes for test runs but not when you want to roll it out commercially. Millions of mosquitoes are needed just to cover one city. Imagine what it’s like when many cities across the world want this innovative solution.
Clearly a more efficient way to separate the sexes of the mosquitoes will be needed. If there’s a huge demand for this product, I’m sure the company will find some solution to this. And if they do, it can really make a big difference to the world.
According to a WHO factsheet released earlier this year, the incidence of dengue has grown dramatically around the world in recent decades. It estimates that there are currently 390 million dengue infections per year. And it cites another study, about the prevalence of dengue, which estimates that 3.9 billion people in 128 countries are at risk of infection with dengue viruses.
And that’s just for dengue. There are many other mosquito-borne diseases like Zika, yellow fever, malaria, chikugunya and so on that can be reduced, if not eradicated, if the Wolbachia-infected male mosquitoes have a chance to do their job.
Oon Yeoh is a consultant with experiences in print, online and mobile media. reach him at oonyeoh@gmail.com