Vampire spiders: The new heroes in the fight against malaria?

Marie-Lyne Fillion
10 May 2016

Above: A jumping spider from the genus Evarcha (Olaf Leillinger, Wikimedia Commons)

Spiders. Are. EVERYWHERE! Planet Earth is home to around 40,000 types of spiders. And 3.5 per cent of the world population—including me and Ronald Weasley—are scared to death of them. That’s right, I have arachnophobia! And I do my best to keep far away from any kind of spider. But there’s one species that is becoming very popular with medical researchers: a type of jumping spider called Evarcha Culicivora.

E. culicivora is known as a “mosquito specialist”. It is very well adapted to hunting mosquitoes and prefers them over other prey. In fact, this spider’s favorite meal is a female Anopheles mosquito carrying blood in its abdomen.

Why is this important? Because that species of mosquito is the main culprit in the transmission of malaria. Of course, the spider doesn’t care about saving human lives. So why does it go through the trouble of targeting certain mosquitoes? And how does it do it?

Did you know? There are about 430 species of Anopheles mosquitoes, but only 30-40 of them transmit malaria.

Jumping spiders have very good vision. They can see their prey, and the prey’s position, in great detail. This not only allows E. culicivora to distinguish a mosquito from other prey, but also helps this spider position itself to attack.

For example, if the spider is facing the front or the side of the mosquito, it will sneak around to the back. As you know from trying to scare people (or from being scared by someone), this is the best place to be when launching a surprise attack! The spider knows this, too, and takes advantage because it means a better chance at catching a yummy meal.

E. culicivora spiders can also tell different species of mosquitoes apart based on body position. The Anopheles mosquito is very recognizable because it rests with its abdomen tilted up in the air. In particular, young spiders prefer this kind of mosquito because it’s is easier to sneak under the mosquito’s abdomen without accidentally touching it. This position also makes it easier to grab onto the mosquito if it tries to fly away or shake off the spider. This is less of a concern for adult spiders since they are stronger than younger ones.

Did you know? Spiders are part of the class Arachnida, which also includes scorpions, mites, and ticks.

Like mosquitoes, E. culicivora is attracted to human odour. They can be found in or around buildings inhabited by people, which are ideal mosquito hunting grounds. Scientists have discovered that even a smelly sock is enough to attract both of these critters. Talk about motivation to pick up your dirty laundry!

The blood in the abdomen of female mosquitoes that have just bit an animal or human gives off a particular odour. This makes them especially easy for E. culicivora to find. But that’s not the only reason these spiders prefer blood-carrying mosquitoes. Eating them also gives E. culicivora a special smell that is attractive to spiders the opposite sex! (Hey! Doesn’t President Snow smell of blood and roses? I think we just found his biggest fan!). In fact, this blood perfume works so well at attracting mates that the spiders continue killing mosquitoes even after they’re full!

Did you know? Between the 2000 and 2015, new malaria cases worldwide decreased by 37%. However, the World Health Organization still estimates that 3.2 billion people are at risk of contracting the disease.

Thanks to its good vision and sense of smell, E. culicivora could be a big help in controlling the spread of malaria. But should we let loose more of these jumping spiders in hopes of killing as many pesky disease-carrying mosquitoes as possible? What might be some pros and cons for both the human population and the surrounding ecosystem?

Learn More!

Mosquito-terminator spiders and the meaning of predatory specialization (2015)
R. Jackson & F. Cross, Journal of Arachnology 43

Mosquito-specialist spiders (2010)
F. Cross & R. Jackson, Current Biology 20

A predator from East Africa that chooses malaria vectors as preferred prey (2006)
X. J. Nelson & R. R. Jackson, PLOSONE 1

Marie-Lyne Fillion

 


Comments are closed.

Comment

Avatar  gucci replica

They can see their prey, and the prey’s position, in great detail. This not only allows E. culicivora to distinguish a mosquito from other prey, but also helps this spider position itself to attack.