Animals

In a remote corner of Brazil’s Amazon rainforest, researchers have spent decades catching and measuring birds in a large swath of forest unmarred by roads or deforestation. An exemplar of the Amazon’s dazzling diversity, the experimental plot was to act as a baseline that would reveal how habitat fragmentation, from logging or roads, can hollow out rainforests’ wild menagerie.

But in this pristine pocket of wilderness, a more subtle shift is happening: The birds are shrinking.

Over 40 years, dozens of Amazonian bird species have declined in mass. Many species have lost nearly 2 percent of their average body weight each decade, researchers report November 12 in Science Advances. What’s more, some species have grown longer wings. The changes coincide with a hotter, more variable climate, which could put a premium on leaner, more efficient bodies that help birds stay cool, the researchers say.

“Climate change isn’t something of the future. It’s happening now and has been happening and has effects we haven’t thought of,” says Ben Winger, an ornithologist at the University of Michigan in Ann Arbor who wasn’t involved in the research but has documented similar shrinkage in migratory birds. Seeing the same patterns in so many bird species across widely different contexts “speaks to a more universal phenomenon,” he says.

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Biologists have long linked body size and temperature. In colder climates, it pays to be big because having a smaller surface area relative to one’s volume reduces heat loss through the skin and keeps the body warmer. As the climate warms, “you’d expect shrinking body sizes to help organisms off-load heat better,” says Vitek Jirinec, an ecologist at the Integral Ecology Research Center in Blue Lake, Calif. 

Many species of North American migratory birds are getting smaller, Winger and colleagues reported in 2020 in Ecology Letters. Climate change is the likely culprit, Winger says, but since migrators experience a wide range of conditions while globe-trotting, other factors such as degraded habitats that birds may encounter can’t be ruled out.

To see if birds that stay put have also been shrinking, Jirinec and colleagues analyzed data on nonmigratory birds collected from 1979 to 2019 in an intact region of the Amazon that spans 43 kilometers. The dataset includes measurements such as mass and wing length taken from 1979 to 2019 for over 11,000 individual birds of 77 species. The researchers also examined climate data for the region.

By taking careful measurements of tropical birds, such as this white-crowned manakin (Pseudopipra pipra), researchers tracked shifts in body size over 40 years.Cameron Rutt

All species declined in mass over this period, the researchers found, including birds as different as the Rufous-capped antthrush (Formicarius colma), which snatches insects off the forest floor, and the Amazonian motmot (Momotus momota), which scarfs down fruit up in trees. Species lost from about 0.1 percent to nearly 2 percent of their average body weight each decade. The motmot, for example, shrunk from 133 grams to about 127 grams over the study period.

These changes coincided with an overall increase in the average temperature of 1 degree Celsius in the wet season and 1.65 degrees C in the dry season. Temperature and precipitation also became more variable over the time period, and these short-term fluctuations, such as an especially hot or dry season, better explained the size trends than the steady increase in temperature.

“The dry season is really stressful for birds,” Jirinec says. Birds’ mass decreased the most in the year or two after especially hot and dry spells, which tracks with the idea that birds are getting smaller to deal with heat stress.

Other factors, like decreased food availability, could also lead to smaller sizes. But since birds with widely different diets all declined in mass, a more pervasive force like climate change is the likely cause, Jirinec says.

Wing length also grew for 61 species, with a maximum increase of about 1 percent per decade. Jirinec thinks that longer wings make for more efficient, and thus cooler, fliers. For instance, a fighter jet, with its heavy body and compact wings, takes enormous power to maneuver. A light and long-winged glider, by contrast, can cruise along much more efficiently.

“Longer wings may be helping [birds] fly more efficiently and produce less metabolic heat,” which can be beneficial in hotter conditions, he says. “But that’s just a hypothesis.” This body change was most pronounced in birds that spend their time higher up in the canopy, where conditions are hotter and drier than the forest floor.

Whether these changes in shape and size represent an evolutionary adaptation to climate change, or simply a physiological response to warmer temperatures, remains unclear (SN: 5/8/20). Whichever is the case, Jirinec suggests that the change shows the pernicious power of human activity (SN: 10/26/21).

“The Amazon rainforest is mysterious, remote and teeming with biodiversity,” he says. “This study suggests that even in places like this, far removed from civilization, you can see signatures of climate change.” More

A Venus’s-flower-basket isn’t all show. This stunning deep-sea sponge can also alter the flow of seawater in surprising ways.

A lacy, barrel-shaped chamber forms the sponge’s glassy skeleton. Flow simulations reveal how this intricate structure alters the way water moves around and through the sponge, helping it endure unforgiving ocean currents and perhaps feed and reproduce, researchers report online July 21 in Nature.

Previous studies have found that the gridlike construction of a Venus’s-flower-basket (Euplectella aspergillum) is strong and flexible. “But no one has ever tried to see if these beautiful structures have fluid-dynamic properties,” says mechanical engineer Giacomo Falcucci of Tor Vergata University of Rome.

Harnessing supercomputers, Falcucci and colleagues simulated how water flows around and through the sponge’s body, with and without different skeletal components such as the sponge’s myriad pores. If the sponge were a solid cylinder, water flowing past would form a turbulent wake immediately downstream that could jostle the creature, Falcucci says. Instead water flows through and around the highly porous Venus’s-flower-basket and forms a gentle zone of water that flanks the sponge and displaces turbulence downstream, the team found. That way, the sponge’s body endures less stress.

Ridges that spiral around the outside of the sponge’s skeleton also somehow cause water to slow and swirl inside the structure, the simulations showed. As a result, food and reproductive cells that drift into the sponge would become trapped for up to twice as long as in the same sponge without ridges. That lingering could help the filter feeders catch more plankton. And because Venus’s-flower-baskets can reproduce sexually, it could also enhance the chances that free-floating sperm encounter eggs, the researchers say.

It’s amazing that such beauty could be so functional, Falcucci says. The sponge’s flow-altering abilities, he says, might help inspire taller, more wind-resistant skyscrapers.

This simulation shows how water flows around and through a Venus’s-flower-basket (gray). Ridges that spiral across the outside of the sponge cause water inside to somehow slow and swirl, forming particle-trapping vortices. And the sponge’s shape creates a gentle zone of slower water that forms immediately downstream, buffering the creature against turbulence. Vertical cross sections contrast the flow activity of the calm zone (nearer the sponge) and the turbulent zone (downstream).G. Falcucci et al/Nature 2021 More

Climate change is interfering with how researchers count bonobos, possibly leading to gross overestimates of the endangered apes, a new study suggests.

Like other great apes, bonobos build elevated nests out of tree branches and foliage to sleep in. Counts of these nests can be used to estimate numbers of bonobos — as long as researchers have a good idea of how long a nest sticks around before it’s broken down by the environment, what’s known as the nest decay time.

New data on rainfall and bonobo nests show that the nests are persisting longer in the forests in Congo, from roughly 87 days, on average, in 2003–2007 to about 107 days in 2016–2018, largely as a result of declining precipitation. This increase in nests’ decay time could be dramatically skewing population counts of the endangered apes and imperiling conservation efforts, researchers report June 30 in PLOS ONE.

“Imagine going in that forest … you count nests, but each single nest is around longer than it used to be 15 years ago, which means that you think that there are more bonobos than there really are,” says Barbara Fruth, a behavioral ecologist at the Max Planck Institute of Animal Behavior in Konstanz, Germany.

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Lowland tropical forests, south of the Congo River in Africa, are the only place in the world where bonobos (Pan paniscus) still live in the wild (SN: 3/18/21). Estimates suggest that there are at least 15,000 to 20,000 bonobos there. But there could be as many as 50,000 individuals. “The area of potential distribution is rather big, but there have been very few surveys,” Fruth says.

From 2003 to 2007, and then again from 2016 to 2018, Fruth and colleagues followed wild bonobos in Congo’s LuiKotale rain forest, monitoring 1,511 nests. “The idea is that you follow [the bonobos] always,” says Mattia Bessone, a wildlife researcher at the Liverpool John Moores University in England. “You need to be up early in the morning so that you can be at the spot where the bonobos have nested, in time for them to wake up, and then you follow them till they nest again.”

In doing so, day after day, Fruth, Bessone and colleagues were first able to understand how many nests a bonobo builds in a day, what’s known as the nest construction rate. “It’s not necessarily one because sometimes bonobos build day nests,” Bessone says. On average, each bonobo builds 1.3 nests per day, the team found.

Tracking how long these nests stuck around revealed that the structures were lasting an average of 19 days longer in 2016–2018 than in 2003–2007. The researchers also compiled fifteen years of climate data for LuiKotale, which showed a decrease in average rainfall from 2003 to 2018. That change in rain is linked to climate change, the researchers say, and helps explain why nests have become more resilient.

These images show bonobo nests at different stages of decay. Knowing the time it takes for a nest to decay is crucial for estimating accurate bonobo numbers.© B. Fruth/MPI of Animal Behavior

By counting the numbers of nests and then dividing that number by the product of the average nest decay time and nest construction rate, scientists can get an estimate of the number of bonobos in a region. But if researchers are using outdated, shorter nest decay times, those estimates could be severely off, overestimating bonobo counts by up to 50 percent, Bessone says.

“The results are not surprising but also highlight how indirect (and therefore prone to errors) our methods of density estimates of many species are,” Martin Surbeck, a behavioral ecologist at Harvard University, wrote in an e-mail.

Technologies such as camera traps can be used to directly count animals instead of using proxies like nests and are the way forward for animal population studies, researchers say. But until those methods become more common, nest counts remain vital for scientists’ understanding of bonobo numbers.

This phenomenon is probably not limited to bonobos. All great apes build nests, and nest counts are used to estimate those animals’ numbers too. So, the researchers say, the new results could have implications for the conservation of primates far beyond bonobos. More

Fingers crossed for finding nothing: July marks the main trapping season to check for Asian giant hornets still infesting Washington state.

The first of these invasive hornets found in North America in 2021, in June, was probably not from a nest made this year, scientists say. So that find doesn’t say how well, or if, the pests might have survived the winter. Yet that hornet shows quite well the relentless risk of newly arriving insects.

That initial specimen, a “crispy” dead male insect lying on a lawn in Marysville, Wash., belongs to the hefty species Vespa mandarinia. Nicknamed murder hornets, these were detected flying loose in Canada for the first time in 2019 and in the United States in 2020 (SN: 5/29/20). Yet the “dry, crispy” male is not part of known hornet invasions, said entomologist Sven Spichiger at a news conference on June 16.

Testing shows the male “is definitely not the same genetic line as the ones we have found,” said Spichiger, of the Washington State Department of Agriculture in Olympia. Neither the U.S. finds, until now all from Washington’s Whatcom County, nor British Columbia’s on the other side of the border are closely related to the newfound hornet. It’s a separate incursion no one had noticed until now.

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This oddball new specimen may help correct the skewed impression that sneaky invasive arrivals are rare. The hornets’ appearance in North America may have been a shock to some, but in reality, worrisome insects show up often, and will probably keep doing so. Fortunately making a permanent home is harder than getting here, scientists say.

When news of the Asian giant hornets’ arrival first broke in 2019, one of the people who was not at all surprised at a foreign species was entomologist Doug Yanega of the University of California, Riverside. “It is very fair to say that there are many invasive species,” he emphasizes. “We just got a new African mantis species in California this past year in LA, and the expectation is that it is likely to spread.”

But even alarming pest arrivals rarely kick up the fuss prompted by Asian giant hornets. At a peak in hornet news during May 2020, Yanega contrasted the new intruders with the South American palm weevil (Rhynchophorus palmarum). That big weevil had reached southern California and could “wipe out every palm tree in the state,” according to Yanega. Yet, “there have been ZERO [national] mainstream media reports about this, an insect that seriously threatens to have a VASTLY greater negative impact on the economy and our way of life than those hornets ever will,” he fumed in an e-mail.

That relentless influx of invading insects may be one reason so few make it into the general news. For instance, U.S. Customs and Border Protection reported 31,785 incidents detecting some pest just for fiscal year 2020.

For 2021, to pick just one example of worrisome arrivals that have not gone viral, inspectors at Washington Dulles International Airport in Virginia and later at Baltimore/Washington International noticed little brown pests called Khapra beetles (Trogoderma granarium) in Basmati rice and then in dried cow peas that travelers were trying to bring in from abroad. Officials banned the contaminated foodstuffs.

The Dulles contraband had the bigger number of living insects: 12 larvae and four adults. Even that tiny number of tiny insects was unacceptable. This is the only insect species that U.S. customs officials act upon even when all specimens are found dead. The beetles nibble stored seeds but will also soil the goods with stray body parts and hairs that can make human babies fed dirty grain quite sick and adults uncomfortable. In 1953, a major California effort started to stamp out infestations of Khapra beetles and eventually preserved crop marketability. But the effort was expensive, costing the equivalent of about $90 million in today’s economy.

Tiny but destructive Khapra beetles (shown, side and front view), which California eliminated at great expense, almost got into the United States at least twice in 2021 in air passenger luggage. Customs stopped those two incursions.Both: Pest and Diseases Image Library, Bugwood.org (CC BY-NC 3.0 US)

Tiny but destructive Khapra beetles (shown, side and front view), which California eliminated at great expense, almost got into the United States at least twice in 2021 in air passenger luggage. Customs stopped those two incursions.Both: Pest and Diseases Image Library, Bugwood.org (CC BY-NC 3.0 US)

Beetles aside, menacing hornets of other species have shown up before the latest Asian giants, says Paul van Westendorp, an apiculture specialist who now strategizes British Columbia’s fight against V. mandarinia. In May 2019, just months before the discovery of an Asian giant hornet’s arrival, a V. soror hornet appeared in Canada. It was “alive, but not for long,” van Westendorp says. “I had a chance to admire that specimen.” Not a frail beast, this species hunts down other insects and has been reported to catch prey as large as a gecko. V. soror looks very much like a V. mandarinia, he says.

Even Asian giant hornets themselves have turned up at least once in the United States before 2020. An inspector in 2016 flagged a package coming into the San Francisco airport holding a papery insect nest but not mentioning insects on the label. The nest held Asian giant hornet larvae and pupae, some still alive when discovered. These and other species of hornets, including the ominously named V. bellicosa, accounted for about half of the 50 interceptions of hornets and yellow jackets flagged from 2010 to 2018 at U.S. ports of entry, researchers reported in 2020 in Insect Systematics and Diversity.  

Only some stowaways will manage to make permanent homes in new territory. Of these, the real troublemakers seem to be a minority. For instance, out of 455 plant-attacking insects that settled into forests in the continental United States, 62 cause noticeable damage, according to a 2011 tally from U.S. Forest Service researcher Juliann Aukema and colleagues. Even a few rampaging invasive pests, though, can get expensive. Biologists are throwing themselves into the fight.

Relentless as the onslaught of unwanted arrivals is, there’s hope for stamping out the more noticeable invasions if caught early. Vespa hornets are “very large-bodied and obvious, so people will see them,” says entomologist Lynn Kimsey of the University of California, Davis, one of the authors of the 2020 hornet overview. A Vespa affinis nest showed up in San Pedro, in Southern California at least a decade ago. However, she says, “it was killed and there’s been no sighting of the species since, as far as I’ve heard.”

Catching such intrusions early isn’t always easy, however. The port of Oakland takes in about 1 million shipping containers from overseas a year, but at best U.S. Department of Agriculture inspectors can check maybe only 10 percent for stowaway insects, Kimsey says. Add to this all the cargo coming into Long Beach, San Diego and the other West Coast ports — plus all the cargo jets. “What’s amazing is that we don’t see more invasives,” she says. “I think this tells you how hard it is for exotic species to get established.”

They’ll keep arriving though. All the more reason to keep an eye out for something funny on the lawn, even if it’s just a withered nugget. More

In an opening scene of the new film Fathom, Michelle Fournet sits at her computer in the dark, headphones on. The marine ecologist at Cornell University is listening to a humpback whale song, her fingers bobbing like a conductor’s to each otherworldly croak and whine. Software converts crooning whale sounds into the visual space of craggy valleys and tall peaks, offering a glimpse at a language millions of years in the making.

Debuting June 25 on Apple TV+, Fathom follows two scientific teams studying the enigmatic songs of humpbacks. The film captivates, diving into the quest to unveil the inner world of these animals and their ever-changing song culture — one considered far older than our ancestors’ first upright steps.

On opposite sides of the Pacific Ocean, scientists head out onto the water. In a mountain-fringed bay in Alaska, Fournet makes repeated attempts to talk to the whales, playing them a painstakingly reconstructed rendition of a yelp that she thinks may be a greeting. In French Polynesia, behavioral ecologist Ellen Garland of the University of St. Andrews in Scotland listens to humpback songs, mapping how they are tweaked, learned and shared by whales across the South Pacific. These settings are stark and gorgeous, their isolation artfully shown through silent, foggy mornings and endless cobalt seas. In a film fundamentally about oceans filled with sound, ample quiet rests on the surface.

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Directed by Drew Xanthopoulos, Fathom portrays humpbacks and other whales as complex, highly social beings without overstated anthropomorphism. In one goose bump–inducing scene, Garland’s narration identifies whales’ social similarities to humans, but set in a totally different environment. Perceiving each other chiefly with sound cast over stupefying distances, “whales evolved to build relationships in the dark,” Garland says.

Fathom also gives an intimate look at what scientists undertake to find humpbacks in the vast ocean. Equipment breaks. Whales prove unpredictable. Strategies must change on the fly. These moments communicate the tough realities of science and the resilience needed for successful research.

Much of the film is immersed in scenes like these, between troubleshooting and long waits on boat surveys. At times, the film’s pace languishes; connections to greater perspectives, such as the possibility of a globally interlinked song culture, are touched on but not fully examined.

Nonetheless, Fournet’s simple distillation of her complex quest lingers: “I’m trying to start a conversation.” Her words remind us that Fathom is inherently seated at the threshold of unfathomable territory.

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Watch a trailer for Fathom. More

The first genetically modified mosquitoes that will be allowed to fly free outdoors in the United States have started reaching the age for mating in the Florida Keys.

In a test of the biotech company Oxitec’s GM male mosquitoes for pest control, these Aedes aegypti started growing from tiny eggs set out in toaster-sized, hexagonal boxes on suburban private properties in late April. On May 12, experiment monitors confirmed that males had matured enough to start flying off on their own to court American female mosquitoes.

This short-term Florida experiment marks the first outdoor test in the United States of a strain of GM male mosquitoes as a highly targeted pest control strategy. This strain is engineered to shrink local populations of Ae. aegypti, a mosquito species that spreads dengue and Zika (SN: 7/29/16). That could start happening now that the GM mosquitoes have reached mating age because their genetics makes them such terrible choices as dads.

The mosquitoes now waving distinctively masculine (extra fluffy) antennae in Florida carry genetic add-ons that block development in females. No female larvae should survive to adulthood in the wild, says molecular biologist Nathan Rose, Oxitec’s chief of regulatory affairs. Half the released males’ sons, however, will carry dad’s daughter-killing trait. The sons of the bad dads can go on to trick a new generation of females into unwise mating decisions and doomed daughters (SN: 1/8/09).

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The trait is not designed to last in an area’s mosquitoes, though. The genetics just follow the same old rules of natural inheritance that mosquitoes and people follow: Traits pass to some offspring and not others. Only half a bad dad’s sons will carry the daughter-killing trait. The others will sire normal mosquito families.

Imagined versions of live-mosquito pest control in Florida have been both glorified and savaged in spirited community meetings for some time (SN: 8/22/20). But now it’s real. “I’m sure you can understand why we’re so excited,” said Andrea Leal, executive director of the Florida Keys Mosquito Control District, at the mosquito test (virtual) kickoff April 29.

The debate over these transgenic Ae. aegypti mosquitoes has gone on so long that Oxitec has upgraded its original more coddled version with one that is essentially plug and play. The newer strain, dubbed OX5034, no longer needs a breeding colony with its (biting) females and antibiotics in easy reach of the release area to produce fresh males.

Instead, Oxitec can just ship eggs in a phase of suspended development from its home base in Abingdon, England, to whatever location around the world, high-tech or not, wants to deploy them. Brazil has already tested this OX5034 strain and gone through the regulatory process to permit Oxitec to sell it there.

The targets for these potential living pest controls will be just their own kind. They represent only about 4 percent of the combined populations of the 45 or so mosquito species whining around the Keys. Other species get annoying, and a more recent invader, Ae. albopictus, can also spread dengue and Zika to some extent. Yet Leal blames just about all the current human disease spread by mosquitoes in the Keys, including last year’s dengue outbreak, on Ae. aegypti.

It’s one of the top three mosquitoes in the world in the number of diseases it can spread, says Don Yee, an aquatic ecologist at the University of Southern Mississippi in Hattiesburg, who studies mosquitoes (SN: 3/31/21). His lab has linked at least three dozen human pathogens, including some viruses and worms, to Ae. aegypti. Although most mosquitoes lurk outdoors in vegetation, this one loves humankind. In the tropics, “the adults are literally resting on the walls or the ceiling,” he says. “They’re hanging around the bathroom.” The species bites humans for more than half of its blood meals.

In a long-running battle with this beast, staff in Florida in late April added water to boxes of shipped eggs and set them out at selected suburban private properties on Vaca, Cudjoe and Ramrod Keys. Other spots, with no added mosquitoes, will be watched as controls. All locations were chosen in part because American-hatched females of the same species were already there to be wooed, Rose says.

Toaster-sized hexagonal boxes (one pictured) that contain eggs of genetically modified Aedes aegypti were set out on selected private property in the Keys in late April. There the males develop normally — and then fly away to mate.Oxitec

Males typically don’t billow out of their boxes in a gray cloud but emerge sporadically, a few at a time. If all goes well in this preliminary test, up to 12,000 GM mosquitoes in total across the release sites will take to the air each week for 12 weeks.

Neighboring households will host mosquito traps to monitor how far from the nursery boxes the Oxitec GM males tend to fly. That’s data that the U.S. Environmental Protection Agency wants to see. Based on distance tests elsewhere, 50 meters might be the median, Rose estimates. 

The distance matters because pest controllers want to keep the free-flying GM mosquitoes away from outdoor sources of the antibiotic tetracycline. That’s the substance the genetic engineers use as an off switch for the self-destruct mechanism in female larvae. Rearing facilities supply the antibiotic to larvae, turning off the lethal genetics and letting females survive in a lab to lay eggs for the next generation.

If GM males loosed in Florida happened to breed with a female that lays eggs in some puddle of water laced with the right concentration of tetracycline, daughters that inherited the switch could survive to adulthood as biters and breeders. The main possible sources in the Keys would be sewage treatment plants, Rose says. The test designers say they have selected sites well away from them.

After the distance tests, bigger releases still start looking at how well males fare and whether pest numbers shrink. Up to 20 million Oxitec mosquitoes in total could be released in tests running into the fall.

Despite some high-profile protests, finding people to host the boxes was not hard, Rose says. “We were oversubscribed.” At public hearings, the critics of the project typically outshout the fans. Yet there’s also support. In a 2016 nonbinding referendum on using GM mosquitoes, 31 of 33 precincts in Monroe County, which comprises the Keys, voted yes for the test release. Twenty of those victories were competitive though, not reaching 60 percent.

The males being released rely on a live-sons/dead-daughters strategy. That’s a change from the earlier strain of Oxitec mosquitoes. Those males sabotaged all offspring regardless of sex. The change came during the genetic redesign that permits an egg-shipping strategy. Surviving sons, however, mean the nonengineered genes in the new Oxitec strain can mix into the Florida population more than in the original version.

Those mixed-in genes from the test are “unlikely” to strengthen Floridian mosquitoes’ powers to spread disease, researchers from the EPA and the U.S. Centers for Disease Control and Prevention wrote in a May 1, 2020 memorandum. Many factors besides mosquito genetics affect how a disease spreads, the reviewers noted. Oxitec will be monitoring for mixing.

There may be at least one upside to mixing, Rose says. The lab colonies have little resistance to some common pesticides such as permethrin that the Floridian mosquitoes barely seem to notice.

Pesticide resistance in the Keys is what drives a lot of the interest in GM techniques, says chemist Phil Goodman, who chairs the local mosquito control district’s board of commissioners. During the dengue outbreak in 2009 and 2010, the first one in decades, the district discovered that its spray program had just about zero effect on Ae. aegypti. With some rethinking of the program’s chemicals, the control district can now wipe out up to 50 percent of mosquitoes of this species in a treated area. That’s not great control, at best. Then when bad weather intervenes for days in a row, the mosquitoes rebound, Goodman says.

The invasive mosquito species Aedes aegypti (shown), which can spread Zika, dengue and yellow fever, is now under attack in the Florida Keys by GM males genetically tweaked to sabotage the American mosquito populations.Joao Paulo Burini/Moment/Getty Images Plus

Since that 2009–2010 outbreak, catching dengue in Florida instead of just through foreign travel has become more common. In 2020, an unusually bad year for dengue, Florida reported 70 cases caught locally, according to the CDC’s provisional tally. 

Traditional pesticides can mess with creatures besides their pest targets, and some critics of the GMO mosquitoes also worry about unexpected ecological effects. Yet success of the Oxitec mosquitoes in slamming the current pests should not cause some disastrous shortage of food or pollination for natives, Yee says. Ae. aegypti invaded North America within the past four centuries, probably too short a time to become absolutely necessary for some native North American predator or plant.

For more details on pretrial tests and data, the Mosquito Control District has now posted a swarm of documents about the GM mosquitoes. The EPA’s summary of Oxitec’s tests, for instance, reports no effects noticed for feeding the aquatic mosquito larvae to crawfish.

Yee doesn’t worry much about either crustaceans or fish eating the larvae. “That’s somewhat analogous to saying, well, we’re concerned about releasing buffalo back into the prairies of the Midwest because they might get eaten by lions,” he says. Crawfish and fish, he notes, don’t naturally inhabit the small containers of still water where Ae. aegypti mosquitoes breed.

Still, new mosquito-fighting options are springing up: Radiation techniques might become precise enough to sterilize males but leave them attractive enough to fool females into pointless mating. And researchers are developing other genetic ways to weaponize mosquitoes against their own kind.

One technique that uses no GM wizardry just infects mosquitoes with Wolbachia bacteria that make biting unlikely to spread dengue. The latest data from Mexico and Columbia suggest this infection “could be effective in the southern U.S. and across the Caribbean,” says biologist Scott O’Neil, based in Ho Chi Minh City, Vietnam, founder of the World Mosquito Program.

He has no plans for working in the United States but is instead focusing on places with much worse dengue problems. His version of the Wolbachia strategy just makes bites less dangerous (SN: 6/29/12). The mosquito population doesn’t shrink or grow less bloodthirsty, so this approach might not appeal to Floridians anyway. More