Insecticide Resistant Mosquito
A hybrid mosquito found in Mali has developed a resistance to the insecticide used in anti-malaria bed nets. Insecticide-treated bed nets (ITNs) are a form of personal protection that has been shown to reduce malaria illness, severe disease, and death due to malaria in endemic regions. According to the CDC, ‘In community-wide trials in several African settings, ITNs have been shown to reduce the death of children under 5 from all causes by about 20%.
Gregory Lanzaro, a medical entomologist at University of California Davis, says he and his team are calling the hybrid mosquito a “super” mosquito as it can withstand exposure to the insecticides used to treat bed nets. The super mosquito is a result of the interbreeding of two species of malaria mosquito.
Lanzaro believes that their study discloses evidence that the introduction of insecticides into the environment of malaria-carrying mosquitoes altered their evolutionary relationship and broke down the “reproductive isolation that separates them.”
“What we provide in this new paper is an example of one unusual mechanism that has promoted the rapid evolution of insecticide resistance in one of the major malaria mosquito species,” Lanzaro asserts. In their study, Prof. Lanzaro illustrates how the hybrid emerged. A type of gene-swapping or “adaptive introgression” transpired at around the same time usage of insecticide-treated bed nets increased.
Malaria is a mosquito-borne disease caused by a parasite. Symptoms of the disease range from fever and chills to flu-like illness. Left untreated victims may develop severe complications and die. According to the CDC, in 2010 an estimated 219 million cases of malaria occurred worldwide and 660,000 people died, most (91%) in the African Region.
The Plasmodium parasite enters the human bloodstream through the bite of an infected mosquito. Once inside the body, the parasite multiplies in the liver, infects red blood cells and disrupts blood supply to vital organs.
Lanzaro was not surprised to find resistance in malaria infected mosquitoes. “Recently,” he adds, “it has reached a level at some localities in Africa where it is resulting in the failure of the nets to provide meaningful control, and it is my opinion that this will increase.”