Spider with appetite for mosquitoes guides war on malaria

Scientist have discovered a Malaysian jumping spider Paracyrba wanlessi, that prefers preying on mosquitoes to any other prey in a revelation that would help curb the spread of the deadly Malaria disease biologically with statistics indicating that about 600,000 lives are lost annually as a result of Malaria menace.

The news follows previous discovery by ICIPE spider researchers on a jumping spider terminator that only preys on female mosquitoes alone. According to Prof Robert Jackson and Dr Fiona Cross from ICIPE, this new species of mosquito terminator Evarcha culicivora, craves all mosquitoes, whether they are larvae or pupae in water or adult terrestrial mosquitoes any mosquito will suffice.

The findings of the research titled “Intricate Predatory Decisions by a Mosquito-Specialist from Malaysia.” Were published in Royal Society Open Science. In the study, almost the only time that the P. wanlessi chose to eat other prey – such as a waterbug – was when there were no mosquitoes to eat.

The spider even chose mosquitoes over lakeflies, which look quite similar to mosquitoes, and regularly chose the mosquitoes over a variety of arthropod prey such as other spiders, fruit flies, mayflies, beetles, water striders and crickets. P. wanlessi even opted for the mosquitoes when it had never eaten a mosquito before.

According to Dr. Fiona Cross P. wanlessi preys on juvenile as well as adult mosquitoes, and expresses a preference for all mosquito stages even when it has never eaten any mosquito (adult or juvenile) before. This is extraordinary, considering that adult and juvenile mosquitoes are very different animals.”

“To make things more complicated, Paracyrba wanlessi prefers mosquitoes in their usual habitat – juvenile mosquitoes in water and adult mosquitoes out of water – but will express a preference for any mosquitoes in either environment when the alternative is non-mosquito prey,” Cross said.

While it is fascinating to imagine how this knowledge of P. wanlessi’s innate penchant for mosquitoes can be used to help control malaria, the researchers cautioned that immediate enthusiasm over the findings would be premature.

“Our focus in this study was to comprehensively investigate Paracyrba wanlessi's prey-choice behaviour," said Prof Jackson. "Very little, to date, is known about this remarkable spider, and our study should be a helpful step in learning more. It might seem tempting to wonder if this spider could be used in the fight against mosquito-borne diseases, especially because it is a predator of juvenile and adult mosquitoes. However, at this stage, it is too early to know,” he explained.

“At this stage, the most important next step is to learn more about the biology of P.wanlessi,” he said. Cross also warned that transferring the Malaysian spider from its normal environment for use in biological control in Africa would be impossible, as the spiders likely wouldn’t survive. What she did recommend, however, was general awareness-raising about spiders and their important roles in our environments.

For example, she said, the original Mosquito Terminator, Evarcha culcivora, native to Lake Victoria in western Kenya, is attracted to the odours of specific plants. By growing these plants in and around homes, people can encourage these malaria foes to live in their homes.

According World Health Organization about 3.4 billion people – half of the world's population – are at risk of malaria. In 2012, there were about 207 million malaria cases (with an uncertainty range of 135 million to 287 million) and an estimated 627 000 malaria deaths (with an uncertainty range of 473 000 to 789 000).

Increased prevention and control measures have led to a reduction in malaria mortality rates by 42percent globally since 2000 and by 49percent in the WHO African Region. People living in the poorest countries are the most vulnerable to malaria. In 2012, 90 percent of all malaria deaths occurred in the WHO African Region, mostly among children under 5 years of age.