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Showing posts with label Animals. Show all posts
Showing posts with label Animals. Show all posts

Saturday, 9 November 2019

Ants trapped for years in a bunker survived in an absolutely terrible way

In the woods of western Poland is a Soviet nuclear base dismantled, which includes two underground bunkers in which nuclear munitions were once kept ... After the military complex was abandoned, these strange artificial grottoes became resting places for them. overwintering bats.

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In the early 2010s, volunteers began to visit these bunkers to monitor the bats population in winter, and discovered a different type of inhabitant ...: a huge mass of wood ants ( Formica polyctena ) trapped on the floor of the bunker, survivor without a queen nor any of their usual comforts. So how did these creatures survive without light and without food ...?

When it was discovered in 2013, this "colony" of underground ants already had about a million living workers and several million dead ... Namely that they did not reproduce: instead, the population had been reconstituted by accident .

The ant colony of the bunker, with a real "cemetery" against the back wall. Credits: Wojciech Stephan / Czechowski et al./Journal of Hymenoptera Research

In the ceiling of the bunker was a rusty ventilation duct, connecting the dark room to the forest above. A colony of giant ants had built a mound on the ground just above the bunker vent, and as the metal rusted, part of their ranks began to fall into the concrete cavern below. ...

The ventilation pipe located on the ceiling of the bunker. Credits: Rutkowski et al./Journal of Hymenoptera Research

The study of the limits of the living conditions of ants is of great interest to some entomologists. For several years, researchers have visited the bunker several times and watched with fascination as this isolated population continued to grow and survive despite a clear lack of light, heat and food.

Now scientists finally know how these trapped insects managed to survive: the mass consumption of their own imprisoned nestmates ...  Cannibalism was suspected by the researchers: you should know that these ant-woods are, after all, the the only major source of food available in this restricted area, other than occasionally dead mice or bats. Moreover, it is known that this particular species consumes its own fallen dead in territorial " ant wars ", and when food is scarce.

To confirm this intuition, a team of researchers collected the bodies of several ants, scattered in the bunker. Looking closely at 150 dead workers, the team found that the vast majority of bodies (about 93%) had holes (as gnawed) and bite marks.

Scientists confirm that these are obvious signs of mass consumption, with virtually no other body in the bunker able to leave these marks.

" The survival and growth of the bunker 'colony' over the years, without producing its own offspring, has been possible thanks to a continuous supply of new workers from the upper nest and an accumulation of corpses,  " concluded the researchers. "  The corpses were an inexhaustible source of food, which allowed the survival of the trapped ants under otherwise extremely unfavorable conditions,  " they added.

The colony built above the ventilation pipe. Credits: Czechowski et al./Journal of Hymenoptera Research

According to the results of the researchers, it seems that the wood ants can face a remarkable adversity to survive. But, fortunately for this colony, the individuals the populated are no longer obliged to fend for themselves: in 2016, the researchers installed a wooden ramp (which can be seen in the image below) in the bunker, connecting the ventilation pipe to the ground. After four months, almost all the trapped ants had deserted the floor of the bunker.

Here is the help given to the ants trapped in the bunker (a simple piece of wood, allowing them to get out of the bunker of death ...). Credits: Rutkowski et al./Journal of Hymenoptera Research

Indeed, now, ants that have the misfortune to fall into the dark bunker, will no longer be forced to resort to cannibalism to survive. They can simply go out and go quietly to their occupation on the surface, in the open air, with their companions.


Wednesday, 6 November 2019

The decline of insect populations over the last decade has been largely underestimated

For several years, biologists have noted a continual decline in insect populations around the world, linked to the disappearance of certain biospheres and the alteration of ecosystems by human activities, particularly the intensification of agriculture and deforestation. . However, a new large-scale study reveals that the magnitude of this decline in insect populations over the last decade has been largely underestimated.

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In a large-scale biodiversity study, an international team of researchers found that insect species in forests and grasslands in Germany had decreased by about a third. And this only in the last decade.

" A decline of this magnitude over a period of just 10 years has completely surprised us, " said Wolfgang Weisser, ecologist at the Technical University of Munich (TUM). " It's scary, but it's the picture in a growing number of studies ."

Between 2008 and 2017, the research team collected more than one million insects from 300 sites in Germany. Of the approximately 2700 species studied, many appear to be declining. In fact, the team said that in recent years, some rare insects have never been found.

A significant drop in insect populations in the grasslands

No matter where the researchers looked, the conclusion was the same. From pastures for sheep to grasslands to forests, the team reported significant losses in insect diversity, and the largest losses were in grasslands, particularly those surrounded by farms.

In this type of environment, insect abundance decreased by 78%, while biomass dropped by 67%. The loss of insects in German meadows has already been demonstrated, but never in such detail. Most of the previous studies focused only on biomass, the total weight of all insects, not the number of species present.

The researchers found a significant decline in the abundance of insect species. Rare species disappear in favor of more common opportunists. Credits: Sebastian Seibold et al. 2019

" The fact that a large part of all insect groups is actually affected has not yet been demonstrated. Before our survey, it was unclear whether and to what extent forests were also affected by the decline of insects, "says TUM ecologist Sebastian Seibold.

Forest environments also affected

In forest areas, biomass has decreased by 40% and the number of species has decreased by a little over a third. According to the team, those who suffered the most were insects that covered long distances. Although this may be due to decimated forests, further research will be needed to determine the cause.

Although the decline in biomass, abundance and number of insect species is higher in grasslands (blue), forests are also affected by these extinctions (orange). Credits: Sebastian Seibold et al. 2019
" Our results show that there is a general decline in biomass, abundance and number of arthropod species across trophic levels. The decline of arthropods in forests shows that loss is not limited to open habitats, "the researchers write.

Rare insects replaced by opportunistic species

Additional research will be needed to obtain a complete picture of these changes in biomass, abundance and diversity - but the data contains some clues. The losses in the German grasslands were the highest among the rarest insects, which could explain to a large extent the alarming numbers.

In the forests, on the other hand, the scenario is different. Here, the biomass of insects has remained relatively constant over 10 years. In fact, the most abundant insects have become even more ubiquitous. This suggests that when insects disappear in forest environments, they are quickly replaced by other, more opportunistic species.

Identify the specific causes of insect decline

In the most catastrophic scenario, some entomologists warned that insects could disappear within a century; others believe that it is more likely that a small number of species will survive by taking advantage of the loss of competitors.

The authors did take climate change into account, but these were beyond the scope of this study. Not everyone is convinced that climate change is the main factor in the loss of insects, but there is good reason to believe that it could help.

" Although the factors of arthropod decline in forests remain unclear, in grasslands these factors are associated with the proportion of agricultural land in the landscape. However, we can not determine whether the observed declines are caused by the effects inherited from historical intensification of land use or by the recent intensification of agriculture at the landscape level.


Saturday, 26 October 2019

Monkeys were caught eating rats in a palm oil plantation in Malaysia

A macaque devouring a rat. | Anna Holzner
Pig-tailed macaques (family Cercopithecidae) feed mainly on sweet fruits and other vegetables. But, to the surprise of the scientists who made this intriguing discovery, they can also eat an astronomical amount of ... rats. Indeed, macaques were caught eating rats in a palm oil plantation in Malaysia.

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The researchers found that, far from being seen as pests, monkeys could ultimately be prime guests in Malaysian oil palm plantations, compensating more than the few fruits they steal by reducing a threat well. more important: rodents.

Over the last six years, scientists from Malaysia and Germany have closely monitored two populations of Pig-tailed Macaques (here in particular Macaca nemestrina) from the south of Segari Melintang Forest Reserve, Malaysia. The monkeys spent a lot of time relaxing in the palm oil plantation surrounding the reserve, which represents about one-third of their living area.

Farmers may not have been happy with the intrusion of monkeys, but for macaques, the palm oil plantation was like a supermarket: indeed, although monoculture encroaches on their habitat, it offers them "cheap" food. Note that these macaques spend several hours a day in the plantations, about half of their total feeding time. As a result, it is not surprising to see them busy eating palm fruit.

What was a little more surprising though, even shocking when scientists discovered it, is the main dish of macaques: rats. " I was stunned when I saw that macaques were feeding on rats in plantations, " says Nadine Ruppert, an ecologist at Universiti Sains Malaysia. " I did not expect them to hunt these relatively big rodents or eat so much meat. They are widely known to be frugivorous primates, which only feast on small birds or lizards from time to time  , "she added.

An adult male pigtailed macaque consuming a rat in oil palm plantations. Credits: Anna Holzner
This observation leads to interesting questions: Are monkeys really the enemies of farmers? Is their presence a lower cost for them, since they perform a service for the least practical fight against rats? Why do these monkeys eat so many rats?

Through their research, scientists have found that monkeys eat more than 12 tons of palm fruit a year. It may sound like a lot, but you should know that this amount is only a little over half a percent of the total production of the plantation area covering their home range ... This is nothing compared to the damage caused by rats, which they can potentially nibble up to 10% of the products of the plantation.

Of course, if the monkeys ate only a few rats from time to time, it certainly would not make a big difference. But it turns out that they can consume very large quantities ... " In discovering cavities in oil palm trunks, where rats seek refuge during the day, a group of pig-tailed macaques can capture more than 3000 rats a year!  Said Anna Holzner, an anthropologist at the University of Leipzig, Germany.

As a result, if a primate-hungry population feeds on rats that cause havoc on the plantations, their damage could be reduced to only 2% (instead of 10%). Of course, there is still the 0.56% damage caused by the monkeys. But the total would represent a loss of less than 3%, which is always more advantageous than the 10% caused only by rats ...

However, in this calculation, one must also consider ethics. Indeed palm oil plantations are important activities in Southeast Asia, but their cost to the environment is more than considerable.

As a result, finding ways to turn these plantations into non-hostile areas for the surrounding wildlife could help to save, in part, the industry's terrible reputation for its impact on wildlife.

" We hope that our results will encourage private and public plantation owners to consider protecting these primates and their natural forest habitat in and around existing and newly established oil palm plantations ," said Anja Widdig. , lead author of the study, also from the University of Leipzig.