Thanks to the excessive use of pesticides such as DDT in the 1950s and 1960s, many mosquitoes around the world now have a good deal of resistance to such chemicals. The emergence of pesticide-resistant mosquitoes and the subsequent failure to control malaria is generally considered one of the major lost opportunities to eradicate a deadly diseases.
Researcher Janet Hemingway claims there might be an upside to such resistance. In a study published in New Scientist, Hemingway reported that a variety of mosquitoes she captured that were resistant to organophosphate insecticides were also less able to transmit a disease caused lymphatic filariasis than flies were. Hemingway speculated that perhaps the resistant mosquitoes might also be less likely to transmit malaria.
“We need to check our facts,” Hemingway told New Scientist. “The research shows we may be able to live with resistance because there may be benefits.”
I don’t think so. As Chris Curtis, a researcher at the London School of Hygiene and Tropical Medicine, told New Scientist, Hemingway’s claims conflict with other studies. In fact given how widely DDT and other insecticides have been used and the large number of resistant mosquitoes, there is certainly no shortage of malaria cases. Even if there was some slight decline in any given mosquito’s ability to transmit malaria, that would seem to be overwhelmed by the sheer number of mosquitoes who survive once they become resistant.
Moreover, while the find is certainly intriguing for lymphatic filariasis — which infects 120 million people around the world and causes swelling in the limbs and genitals — there clearly is an environmental cost to pay for excessive spraying of DDT that is probably not worth it. The resistant mosquito strains emerged after unbelievably large quantities were sprayed largely for agricultural purposes rather than for malaria control.
Judicious application of organophosphate insecticides along with continued research on better treatments and possible cures or vaccinations for malaria makes a lot more sense.
Source:
Resistance is useful: Overuse of insecticides could be a blessing in disguise in fighting disease. Andy Coghlan, The New Scientist, October 25, 2000.