The Quest for A Total Annihilation of the Killer Mosquitoes

Mr Kunle tried to swath the annoying buzz in his ear and only ended up slapping himself. It hurt, but that had been his nightly routine for the past one week. The mosquitoes appear resistant to all the insecticide he could lay his hands on. As he tried again to sleep, the buzz increases making sleeping difficult. More mosquitoes. He is up for a sleepless night. He only wishes the world would be free of these tiny blood-sucking annoying flying insects.

Kunle is not alone in that wish to get rid of the blood-sucking little vampires that cause an estimated 247 million malaria cases with at least a million fatalities. Mosquitoes are among the species that have up to 3500 variants. Out of these only about a 100 of it bothers to bite humans.

In the midst of this handful, there are three recognised species responsible for sending many people to their early graves in the worst-hit countries in Africa which are Nigeria, Uganda, Democratic Republic of Congo, Mozambique, Cote d'Ivoire and the United Republic of Tanzania. These countries account for 47% of the total malaria cases.

The species of mosquitoes we have to blame for this are Anopheles, Aedes and Culex.

The female species are capable of laying 1000 eggs in her lifetime which can be up to 30 days with the females living longer than the male. The eggs are capable of being dormant for up to a decade and only hatch under the optimum condition.

Unraveling the mystery

In the Sahel region of Africa, researchers looking for ways to permanently place the nail on the coffin of mosquitoes are working on an interesting theory. Like all the affected region in Africa, there is the period where there are rains and a period of dryness with no rain. In the no rain period popularly known as dry season in the Sahel regions of Africa, the population of mosquitoes during the extreme dry period is almost zero. But a weird phenomenon takes place in the first three days of rain; the mosquitoes reproduce and are everywhere. This phenomenon is weird because the entire average life cycle period of adult mosquitoes from egg to an adult is at least eight days.

What the researchers noticed was that fully grown ready-to-suck-blood mosquitoes mysteriously lays siege on the population in just after three days of rain. The answer to this mystery unravels the fact that the adult mosquitoes did not just complete their lifecycle in under three days, a biological improbable, but rather that the adult mosquitoes hide during the dry season waiting patiently to run amock on the first three days of wet weather.

An Idea is Born

The idea is simple, locate the hiding place of these mosquitoes and destroy them before the rains.

Enter Dana to the game. Dana is a German Shephard with a difference. She has the unique ability to sniff out the hiding places of dormant mosquitoes in Mali. You can watch her in action here.

The effort was from the team led by Tovi Lehmann of the U.S. National Institute of Health's Lab of Malaria and Vector Reseach. Dr Tovi Lehmann is a research entomologist. An entomologist studies insects and is a branch of zoology.

His team comprising of Africans, Americans, and other partners have spent an estimated $700,000 in their quest to seek out hiding places of insects using every method including the specially trained dog, Dana, which with a unique ability to smell out the hidden mosquitoes camp.

Though there is the possibility that the vast swarms of mosquitoes observed may be from migration from nearby places facilitated by strong winds, the researchers think aestivation, similar to hibernation where some insects go dormant during the dry spell only to appear during the rain via a simple experiment the team did. They painted about 7000 mosquitoes which they released to the wild. After a year, they were surprised to see some mosquitoes with the same paint on them. Since mosquitoes have a lifespan of only about 30 days on the extreme side, the only explanation is that the mosquitoes hibernated to reappear the next year during the rains in May.

Going the genetic route

The sterile insect technique (SIT) is not a new method of pet control. The technique has proven useful in the r=eradictation of screw-worm fly (Cochliomyia hominivorax (Coquerel)) from locations in Central and North America. This stemmed the losses in livestock in the area, a program that kicked off in 1957

While Dr Tovi Lehmann is looking to wipe out the mosquitoes while they "sleep" during the dry season, some British researchers are looking at attacking the little monsters via their genetic makeup.

Dr Andrea Crisanti a scientist from the Imperial College in London wants to tamper with the genes of females mosquitoes making them sterile. If the entire female mosquitoes were unable to reproduce, it means we have less than two months to say goodbye to mosquitoes forever. The idea is a great one, but like all great ideas, they do not come without its hitches.

First, how do we get a great convention that will be attended by all the mosquitoes so we can effectively get to work and re-engineer their genes?

The scientist has the answer to that; we do not need the mosquitos in one place to carry out this gene war. All they need is their trusty CRISPR-Cas9 excellent genome-editing tool.

By screwing up the chromosomes, the mosquitoes can now pass this infertility gene to the next generation. The team have successfully done this editing on 600 mosquitoes with 75% of the population successfully passing down the mutation after four generation. That in itself shows the idea may just be what we need to say a final bye to malaria. But is it so?

The thing is that no one is sure how this genetic business will end up to. Will type of traits will these mutant mosquitoes have? Will we have genetic mayhem of a different breed of mosquitoes with new capabilities on our hands?

The director of Malaria Foundation, Ingeborg van Schayk echoed this sentiment too.

'We do not support the release of GM mosquitoes as long as the long-term effects on people and their environment remain uncertain... We don't know if malaria mosquitoes will adapt to being "modified" and leave us with even bigger problems.' DailyMail

The DDT solution

There is this saying by the philosopher George Santayana, that human is doomed to repeat the history if they refuse to learn from it.

In the 60s, there was this mad rush to kill of mosquitoes with the use of the chemical Dichlorodiphenyltrichloroethane or DDT for short. It was a colourless and odourless chemical.

Thousands of drums of DDT later, we had a 95 percent drop in the number of deaths associated with malaria. But soon a book written in 1962 by Rachel Carson, Silent Spring, dropped the many disadvantages of the use of DDT including it being carcinogenic to humans plus other threats to wildlife, started the movement which leads to DDT being outlawed in 1972.

Recently there have been calls to bring back DDT in the fight against the zika virus, a virus spread by mosquitoes. Some African countries still use DDT. South Africa in the year 2000 reintronduce DDT. They limited the use to only walls indoors and the 61,000 recorded cases dropped by half after half a year of use.

Proponents of the genetically modified mosquitoes are of the opinion we should first give it a try and see how it pans out before criticising it.

Conclusion

Will it too bad for the environment/biodiversity if all the mosquitoes are eliminated? For instance, a declining snake population in the USA due to use of pesticides may lead to a drastic increase in mice, rats, insects, small amphibians, and the other things they prey on.

Although mosquitoes kill a lot of people, they are not an invasive species. Ironically the humankind is the number one invasive species.

But in the case of mosquitoes, extinction of the little annoying pesky flying things is something no one will cry over.

We can all breathe a sigh of relief, after all, we have had an entire species of beloved animals like the Tasmanian Tiger and passenger pigeon go extinct plus a host of others and we are just ok without them.

REFERENCES

1. WHO: Malaria Report
2. The Mosquito Hunt
3. Mosquitoes engineered to pass down genes that would wipe out their species
4. Keeping Up With the Fast-Moving Science of Gene Drives
5. Screwworm control and eradication in the southern United States of America