A promising new tactic in the effort to control malarial infections may be — sorry, arachnophobes — spiders.
A multi-decade (and still going) study conducted through the University of Canterbury in New Zealand and published in the July 2015 edition of Journal of Arachnology finds there are two types of spiders that are skilled mosquito killers.
Paracyrba wanlessi spiders are native to Southeast Asia. These spiders live in hollow canes of bamboo, called culms, in pools of stagnant water. This is perfect for preying on mosquitoes — larval, pupal and adult, alike — along with other water bugs.
The keenly sighted, eight-legged Evarcha culicivora spider, found around Lake Victoria on the border of Kenya and Uganda, also has a taste for mosquitoes.
“Like ‘Bram Stoker's Dracula' or Arnold Schwarzenegger in the James Cameron movie 'The Terminator,' these little specialist predators ignore any other insects that get in the way as they pursue their target victims — mosquitoes,” says arachnologist Fiona Cross, co-author of the study, in a statement released by the university.
E. culicivora is a complicated little creature, writes Cross in an email. Its biology is tightly connected to its preferred prey of mosquitoes, as well as to humans. That's because it's not actually the mosquito that this spider is attracted to. It's human blood these spiders find irresistible, making. E. culicivora the only known predator to select prey based on the prey's diet.
Despite a voracious taste for our blood, E. culicivora isn't physically able to bite humans, which is why these spiders rely on an indirect method to satisfy their bloodlust. E. culicivora preys upon the blood-sucking Anopheles gambiae mosquitoes, specifically the females, who are known to carry and spread malaria. It's these females the spiders seek out, visually assessing their posture, among other identifiers, to figure out which mosquitoes are engorged with human blood.