National Geographic : 2016 Aug
Science vs. mosquitoes 59 +100% No change NORTH AMERICA SOUTH AMERICA EUROPE TROPIC OF CANCER TROPIC OF CAPRICORN EQUATOR ASIA AFRICA AUSTRALIA –100% random bodies of water that humans tend to create just by living day to day: A pet dish will do, or an upturned jar top, a discarded tire, a cistern with a cracked lid. She will spread each egg batch around, making it much harder for natural or man-made interventions to wipe out a whole brood at once. She can find egg-laying spots that aren’t wet yet but will be, when the weather changes; she’s that ingenious. She bites all day long; bed nets (which have helped re- duce worldwide malaria deaths because the malaria-carrying Anopheles tends to bite at night) aren’t as effective against Zika and other Aedescarried diseases. And when you reach down to slap a biting Ae. aegypti, she’s likely to dart lightly away, es- caping the descending palm of death, and then come back to bite you again. “So she makes sure you get a multiple dose,” says University of Kentucky entomologist Grayson Brown, who in March went to Brazil, where Zika has hit hard, to help lead an Aedes aegypti summit. “Crisis in the Americas” was the summit’s billing, and Brown says the discussion includ- ed more crises than the potentially explosive spread of Zika. Yellow fever remains a terrible worry, as do dengue, chikungunya, and Maya- ro, a mosquito-spread monkey virus infecting people in northwestern Brazil. Defensive strat- egies under consideration range from simple to scientifically ambitious: campaigns to clean out breeding spots, experimental trap designs, larva-killing acoustic signals, plans to prevent mosquitoes from reproducing successfully by infecting them with bacteria or altering their genetic makeup. One presentation described an “autocide” technique that takes lethal ad- vantage of the way Ae. aegypti spread each brood to multiple sites: lace the first with larva poison that the mosquito takes in when she lands. Then at her next site, she poisons her own offspring. No silver bullets, though. “There is not going to be a silver bullet,” Brown says. “It’s going to be hard work. But it has to be done, on a year- to-year basis—for forever.” j Up to 600 million more people may be exposed to invasive Zika-carrying Aedes albopictus. Some regions could become too hot for mosquitoes. Projected change in suitable habitat by 2050 for Aedes albopictus Skeeter Scatter Mosquitoes thrive in a tropical climate. Scientists expect this zone to widen toward the poles as the planet warms.