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      How these parasitic worms turn brown shrimp into bright orange “zombies”

      news.movim.eu / ArsTechnica · Thursday, 7 September, 2023 - 21:02 · 1 minute

    a bright orange shrimp

    Enlarge / Orange amphipods caught the eye (and interest) of Brown University graduate students conducting field research. (credit: David Johnson)

    Scour the salt marshes of Plum Island Estuary in Massachusetts and you're likely to spot bright orange shrimp lurking among the vegetation and detritus. That unusual hue is a sign that a shrimp has been infected with a parasitic worm, which also seems to affect the shrimp's behavior. Infected shrimp typically become sluggish and spend more time exposed in the open marsh, easy pickings for hungry birds. Now biologists at Brown University have sequenced the DNA of these shrimp to hone in on the molecular mechanisms behind the changes, according to a recent paper published in the journal Molecular Ecology.

    “This may be an example of a parasite manipulating an intermediate host to ensure its own transmission between hosts,” said co-author David Rand of Brown University, drawing an analogy to how malaria spreads to humans via the intermediary of mosquito bites. “Rabies could be another relevant example: it drives infected individuals ‘mad’ so they bite others and infect the next host. Learning the molecular mechanisms of these kinds of host-parasite interactions can have important implications for how to manage pathogens generally, and in humans.”

    Parasites that control and alter the behavior of their hosts are well-known in nature. Most notably, there is a family of zombifying parasitic fungi called Cordyceps —more than 400 different species , each targeting a particular insect species, whether it be ants, dragonflies, cockroaches, aphids, or beetles. In fact, The Last of Us game co-creator Neil Druckmann has said the premise was partly inspired by an episode of the BBC nature documentary Planet Earth (narrated by Sir David Attenborough) portraying the "zombification" of an ant in vivid detail . Scientists are keen to study Cordyceps to learn more about the origins and intricate mechanisms behind these kinds of pathogen-based diseases.

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      The Namibian fairy circle debate rages on: Could it be sand termites after all?

      news.movim.eu / ArsTechnica · Wednesday, 26 July, 2023 - 21:48 · 1 minute

    Fairy circles in the Namib Desert.

    Enlarge / Bare, reddish-hued circular patches in the Namib Desert known as "fairy circles" are also found in northwestern Australia. (credit: UHH/MIN/Juergens)

    Himba bushmen in the Namibian grasslands have long passed down legends about the region's mysterious fairy circles: bare, reddish-hued circular patches that are also found in northwestern Australia. In the last 10 years, scientists have heatedly debated whether these unusual patterns are due to sand termites or to an ecological version of a self-organizing Turing mechanism. Last year, a team of scientists reported what they deemed definitive evidence of the latter, thus ruling out sand termites, but their declaration of victory may have been premature. A recent paper published in the journal Perspectives in Plant Ecology, Evolution, and Systematics offers a careful rebuttal of those 2022 findings, concluding that sand termites may be to blame after all.

    As we've reported previously, the fairy circles can be as large as several feet in diameter. Dubbed "footprints of the gods," it's often said they are the work of the Himba deity Mukuru , or an underground dragon whose poisonous breath kills anything growing inside those circles. Scientists have their own ideas.

    One theory—espoused by study co-author Norbert Jürgens, a biologist at the University of Hamburg in Germany—attributed the phenomenon to a particular species of termite ( Psammmotermes allocerus ), whose burrowing damages plant roots, resulting in extra rainwater seeping into the sandy soil before the plants can suck it up—giving the termites a handy water trap as a resource. As a result, the plants die back in a circle from the site of an insect nest. The circles expand in diameter during droughts because the termites must venture farther out for food.

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      Study confirms that painting eyes on cow butts helps ward off predators

      Jennifer Ouellette · news.movim.eu / ArsTechnica · Tuesday, 18 August, 2020 - 12:43 · 1 minute

    Eyes painted on cattle rumps trick lions into thinking they have lost the element of surprise, a new study suggests.

    Enlarge / Eyes painted on cattle rumps trick lions into thinking they have lost the element of surprise, a new study suggests. (credit: Ben Yexley )

    Cattle herds in the Okavango delta region in Botswana are plagued by attacks by lions and other predators, prompting farmers to retaliate by killing the predators. An alternative nonlethal technique involves painting eyes on the butts of cattle to trick ambush predators like lions into thinking they've been spotted by their intended prey. It's called the " Eye-Cow Project ," and a recent paper published in the journal Communications Biology provides some solid empirical evidence for the practice. There are now practical guides for using the "eye-cow" technique available in both English and Setswana, so farmers can try it out for themselves.

    Neil Jordan, a conservation biologist at the University of New South Wales in Australia, came up with the idea several years ago while he was doing field work in Botswana. Local farmers killed a pair of lionesses in retaliation for preying on their herds of cattle, and Jordan wanted to come up with a non-lethal alternative. The African lion population has dropped significantly from more than 100,000 in the 1990s to somewhere between 23,000 and 39,000 in 2016—much of it due to retaliation killings.

    Jordan knew that butterfly wings sporting eye-like patterns are known to ward off preying birds, and are also found in certain fish, mollusks, amphibians and birds, although such patterns had not been observed in mammals. He also discovered that woodcutters in Indian forests have been known to wear masks on the backs of their heads to discourage any tigers hunting for prey. He had observed a lion stalking an impala, and noticed the predator gave up the chase when the prey spotted it. Lions are ambush hunters, Jordan reasoned, and decided to test his "detection hypothesis" that painting eyes on the butts of cows would discourage predatory behavior from the local lion population.

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      Rebellyons-nous, occupation du pont Wilson à #Lyon

      Timothée Jaussoin · Monday, 16 September, 2019 - 07:46 edit · 1 minute

    Le dimanche 15 septembre 2019, sous un soleil de plomb nous avons bloqué avec succès le pont Wilson en plein centre de #Lyon.

    Cet évènement coup de poing, non-violent et festif nous a permis de dénoncer la gravité de la situation face aux chamboulements écologiques et climatiques que nous vivons présentement et à venir très prochainement.

    Cet évènement a été relayé dans la presse par Rue89 et a fait l'ouverture du journal du soir France3 Rhône-Alpes.

    De nombreuses actions de désobéissance civiles non-violentes sont à prévoir prochainement. Plus d'informations sur le site officiel de XR France et sur le site international.

    #ecology #climate #france #extinctionrebellion #xr #action #movement #bridge #pont