A plague of locusts that darken the sky and destroy everything that grows has been known since biblical times and today threatens the food security of millions of people in Asia and Africa.
But a new discovery reported Thursday — a pheromone emitted by insects to avoid cannibalism in a flock — could potentially pave the way for curbing voracious pests.
Study leader Bill Hansson, director of evolutionary neuroethology at the Max Planck Institute, told AFP that the new paper, published in The sciencebased on previous studies that found that swarms are not driven by cooperation, but by the actual threat of consumption by other locusts.
Although disgusted by modern humans, cannibalism is widespread in nature, from lions that kill and devour other cubs to foxes that consume dead relatives for energy.
For locusts, cannibalism is thought to serve an important ecological purpose.
The migratory locust (Locusta migratoria) occurs in many forms and behaves so differently that until recently it was thought that they were completely different species.
Most of the time they exist in a “solitary” phase, keeping to themselves and eating relatively little, like timid grasshoppers.
But when their population density increases due to rains and temporary good breeding conditions followed by food shortages, they undergo major behavioral changes due to the release of hormones that activate them, causing them to flock and become more aggressive.
According to a 2020 study by Ian Cousin of the Max Planck Institute, this is known as the “herd” phase, and the fear of cannibalism is thought to help the swarm move in one direction, from an area of lower to higher food concentration. for animal research.
Hansson explained that “the locusts eat each other from behind”.
“So if you stop moving, you will be eaten by another, and this led us to believe that almost every endangered animal has some kind of countermeasure.”
Through painstaking experiments that took four years to complete, Hansson’s team established for the first time that rates of cannibalism did increase as the number of “herd” caged locusts increased, proving in the lab what Cousin observed in the field in Africa (t .trigger point was around 50 per cage).
They then compared the scents emitted by solitary and gregarious locusts and found 17 odors emitted exclusively during the gregarious phase.
One of these, known as phenylacetonitrile (PAN), has been found to repel other locusts in behavioral tests.
PAN is involved in the synthesis of a potent toxin sometimes produced by locust locusts—hydrogen cyanide—so the release of PAN seems to be appropriate as a signal to tell others to back off.
To confirm the discovery, they used CRISPR editing to genetically modify the locust so that it could no longer produce PAN, which in turn made it more vulnerable to cannibalism.
To further confirm, they tested dozens of locust olfactory receptors and eventually settled on one that was highly sensitive to PAN.
When they edited the locust’s gene so that it no longer produces this receptor, the modified locust became more cannibalistic.
Researchers Ian Cousin and Einat Cousin-Fuchs wrote in a related commentary in the journal Science that the discovery helped shed light on the “complex balance” between mechanisms that cause migratory locusts to cluster together rather than compete with each other.
So future locust control methods may use technologies that tip this delicate balance in the direction of increased competition, but Hansson warned: “You don’t want to eradicate this species.”
“If we could reduce the size of the swarms, send them to areas where we do not grow our crops, then a lot could be gained,” he added.
quotes: Scientists Find Chemical That Stops Locust Cannibalism (2023 May 7), retrieved May 7, 2023 from https://phys.org/news/2023-05-scientists-chemical-locust-cannibalism.html.
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Research published last year by IpasA US-based reproductive justice NGO has found that global warming has exacerbated existing gender inequalities and directly or indirectly affected women’s sexual health, pregnancy outcomes, contraceptive use and fertility intentions in Bangladesh and Mozambique, two climate-sensitive countries.
The report says that during extreme weather events exacerbated by climate change, such as cyclones, access to medical care and contraceptives was limited. The researchers also found that the climate crisis has exacerbated economic instability and added an additional burden to women’s caregiving responsibilities.
In some cases, this could mean women taking on dangerous jobs to provide for their families, says Sally Deikerman, a senior researcher at Ipas who worked on the report.
“You, as a woman, may be forced to roam waist-deep in water where you catch fry to feed your family, and these rivers are not only polluted by cyclones and the destruction of sewer systems, but sea levels are rising, leading to more and more salinization of the water,” she said. “It directly affects their reproductive organs, causing infections, cancer and injury.”
In Sathira, salt water intrusion has cut off access to clean drinking water, Akhter said.
“There is not a drop of fresh water in the whole area,” she said. “It will take two hours to get fresh water.”
Fatima Idris Eva, a health worker in the Shyamnagar city of Sathira, said she had noticed an increase in the number of patients, including men, with sexual or reproductive ailments over the past two years. According to Eva, this includes women reporting irregular periods, discharge, and sores around the uterus.
“The water in different parts of Shyamnagar is extremely salty,” she said in Bengali. “We have a lot of patients coming in who have uterine problems due to drinking salt water. It’s worrisome.”
But the burden on some women may come long before climate-related health problems arise. Poor families may force their daughters to drop out of school to work or decide to marry off their girls at an early age to alleviate financial stress. Akhter said she herself stopped going to school and got married after Cyclone Ayla that hit Bangladesh in 2009 left her parents in a financial crisis.
“This salt water ruined my childhood, school and life,” she said.
Similarly, twelve-year-old Sakila Akhtar had her childhood years stolen to help her family out of poverty. She said that she once dreamed of becoming a politician in order to change the fate of people in her hometown, but now she is the mother of a one and a half year old daughter.
“I wanted to discover the world in different ways and be able to do many things, like crafts, but now I have to work as a day laborer with a child in my arms,” Akhtar said in an interview in Bengali. “My father has nothing. I had to settle down and get married. My husband is also poor.
Akhtar said she has irregular periods and heavy discharge and her doctor recommended fresh water bathing, but there is none nearby.
Jahanara Begum, 65, remembers when it wasn’t always like this.
“Once there was fresh water here,” she said in Bengali, adding that she now has to travel more than 4 miles to bring drinking water.
Even during the rainy season, households cannot store enough rainwater to last for a long time.
Begum said her husband was ill and she was suffering from uterine cancer and diabetes. Prolonged exposure to brackish water also caused her to itch all over her body.
“I visit doctors and take medication, but there is no solution,” she said. “So many diseases have settled in my body in these few years.”
Women’s reproductive health risks are expected to rise as cyclones and floods become more frequent and intense due to global warming, and as sea levels continue to rise. Studies show that global average sea levels have risen more than 8 inches since 1880, and scientists predict that by 2050 roughly 17% of Bangladesh could be flooded.
“Here everything turns into a cyclone,” said 12-year-old Akhtar. “Here, thinking about the future of people, the storm breaks houses, breaking people’s lives. Here everyone is happy, but everyone is sick.”
When two rivers meet they are sometimes shy to mix. The muddy load of sediment carried by one keeps a distance from pure blue-green of another. Each one reflects a color the landscape he carved, sometimes with caution and sometimes with turbulence.
The steep walls of the canyon testify and scars of steady descent water molecules attracted by gravity destroying crystals and grains, craving clay particles that fall and drift in the stream. Rivers come out and meander away from the harsh mountains and to each other begin to unload their cargo.
Separate paths become one and a thicker stream dives, hiding your sedimentary past along the mixing line where whirlpools test the water. Clouds and clarity complement each other, and, over time, dispersion and mixing shift the current into balance.
This article was originally published as Confluence in Scientific American 328, 5, 24 (May 2023).
doi: 10.1038 / scientific American 0523-24
ABOUT THE AUTHOR(AH)
Marianna Karplus, a geophysicist and associate professor at the University of Texas at El Paso, was inspired to write poetry during her scientific field trips to the US west, the Himalayas and Antarctica. Her poems have been published in several literary magazines.
Migratory songbirds usually fly under the cover of darkness, but the reason for their flight has long eluded researchers. Now, a couple of studies show that birds rely on the onset of twilight and the assumption of clear skies ahead as cues for flight.
The study, published in the journal Movement Ecology, used radio tracking devices and analyzed data from nearly 400 songbirds belonging to nine migratory species, including the yellow-rumped warbler, American redstart and Bicknell’s thrush.
Like most other migratory birds, these species migrate at night, probably to avoid predators, keep cool, and use the daylight hours for feeding. However, the exact reasons why they start their flights when they do so have long been a matter of debate, with some scientists suggesting that they time their sorties to maximize night flight time, or that they rely on celestial objects. such as visible stars, for flight reference.
To try to better understand the timing of birds, the researchers decided to conduct their research where migration begins rather than at stopping points along the way. This allowed them to reduce the impact of variables, such as fuel availability, that could influence the birds’ flight decisions.
The radio data showed a much narrower migration take-off window than expected. ninety percent of the birds identified by the researchers as capable of seasonal migration did so within 69 minutes of dusk.
“It’s a very narrow window, which suggests there’s something important going on at this time of night,” said Nathan Cooper, a research ecologist at the Smithsonian National Zoo and Institute for Conservation Biology and the paper’s first author. news release. “And we argue that this constant early-night departure time is related to the maximum increase in night flight time.”
Second analysis disclosed that migratory songbirds are good meteorologists. When the researchers took a closer look at the four species, they found that the likelihood of departure was “associated with changes in barometric pressure, almost entirely independent of species, season, or location.” They are likely to depart when the barometric pressure has risen in the previous 24 hours, indicating good weather in the coming days.
However, the weather is likely just one of many factors driving the birds to migrate, the researchers say, citing other sources. research this suggests that the timing of migration also depends on sex, age, and celestial signals.