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A peep into fascinating world of insects Antarctic bacteria a clue to different kinds of life Prof Yash
Pal THIS UNIVERSE |
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A peep into fascinating world of insects Insects dominate the animal kingdom, both in terms of numbers and variety. According to a rough estimate, insects constitute 90 per cent of the animal kingdom. These six-legged animals, which have been living on earth for more than 250 million years, are very successful in adapting to life and have exploited all kinds of environmental niches, ranging from snow-clad mountains to tropical forests and from deserts to rainforests. Though we presume insects as our competitors, the fact remains that human beings compete with insects. Only 5 per cent of the insects are pests and rest of them are either useful or harmless. In fact, fascinating world of insects is not boring but really very interesting. The insect world is so diverse in sizes that you can find an insect ranging from few millimeters (trichgrommatid wasps) to around 30 cm (stick insect) in length. Insects can also defy the law of gravity due to the air drag which is proportional to the surface of a moving object. They can carry weight many times heavier than their own weight. You might have seen ants taking loads of wheat or rice grain for storage in their colonies. A flea can jump horizontally up to 13 inches and vertically up to 7 inches. If a man were to achieve the same feat, he would have to jump horizontally 700 feet and vertically 450 feet. Being small creatures, insects are vulnerable to attacks by frogs, lizards, birds, mammals and predatory members of their own group, but they have developed certain mechanisms to protect themselves from their enemies. Mimicry is very common in butterflies, stick and leaf insects, mantids, etc. For example, in stick insects Carausius morosus, the hind wings are highly coloured but they are concealed during rest and the insect become motionless looking like a dried twig. The limbs in this condition can be moved into any position and will stay there as if the joints are made up of wax. Similarly, leaf insect, Phyllium crurifolium, looks like a leaf as the pattern on the wings is like leaf venation and it becomes difficult for the predator to differentiate between the leaf and the insect. Oriental butterfly, Kallima sp., provides one of the best examples of camouflage sitting with its wings folded beside dry leaves, and mimic dead leaves. It also copies the leaf pattern such as moulds or rusts or holes often seen in dead leaves. Some loopers feign death, appear like dry twigs and hence go unnoticed. Many species release chemicals which are toxic, deterrent or unpalatable, thereby escaping predation. The cantharid beetles, Mylabris spp., are highly coloured and easily spotted by any insect eating animal, but the cantharadin emitted by adults have unpleasant effects. Therefore, the predators avoid eating them. Cantharadin can cause blisters on human skin. The hair of caterpillars often contains histamine and pain-producing substances and in general, hairy caterpillars cause rashes on the human skin. The bombardier beetle, Brachimus sp., ejects foul-smelling, hot and volatile spray containing hydroquinones and hydrogen peroxide, with a district audible explosion towards the enemy and, therefore, escapes predation. The larvae of swallowtail butterflies possess a horn-like structure, the osmeterium, behind the head, which is protruded in case of danger, releasing butyric acid that repels the enemy. So, it is a combination of visual threat and repellent odour. Many species of phytophagous insects have developed the capacity to sequester deterrent substances of plants in order to utilise them as defensive tool against predators. Ak grasshopper, Poekilocerus pictus, sequesters the toxins, calactin and calotropin to ward off the enemy. Monarch butterfly, Danaus plexippus, one of the most frequent insects in the US is known for its ability to ingest toxic chemicals (cardioglycosides) produced by its milkweed host plants and storing toxin for its own protection. Both larvae and adults are toxic to the potential predators (birds) and they display the toxicity through warning colouration. The viceroy butterfly, Basilarchia archippus, which is palatable, mimic monarch colouration, thereby avoids predation. Some insects like termites, ants and bees show the degree of specialisation to which insects have reached. They have evolved their own division of labour and even their own language. Honeybees have altruistic behaviour, and it only stings in case of emergency because after stinging, the bee is sure to die. If there is no danger, these labourious insects remain busy in their chores and will not harm you. Mosquitoes alert you before sucking your blood by putting ‘music’ into your ears but are killed so often. This ‘music’ is not generated by mouth but it is the humming sound that is produced by buzzing of their wings. Bees also produce humming sound around their colonies and also in the fields where they forage. The shriek sound in forests that you hear during summer is of male cicadas to call their female counterpart for mating. It is generally said that cicadas are lucky because they have voiceless females. The nymphs of cicada take 17 years to come out of soil as adult. Moths and butterflies have so beautiful colour patterns and designs on their wings that can serve as a source of designing for textile mills, but in our country special attention towards this aspect is required. The Japanese have a highly developed tradition of aesthetic appreciation for insects which is reflected in their art and literature. The Chinese hold singing crickets in very high esteem. On the whole, the insect world is fascinating. The writer is Senior Entomologist at Dr Y.S. Parmar University of Horticulture and Forestry,
Nauni (Solan)
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Antarctic bacteria a clue to different kinds of life A study by polar researchers has revealed an ancient community of bacteria able to thrive in the lightless, oxygen-depleted, salty environment beneath nearly 70 feet of ice in an Antarctic lake, giving insight into the unique ecosystem. The research, funded by the National Science Foundation and NASA, provides clues about biochemical processes not linked to sunlight, carbon dioxide and oxygen — or photosynthesis. The authors of the study say it may explain the potential for life in salty, cryogenic environments beyond Earth, where energy in ecosystems is typically fueled by the sun. The study, published this week in Proceedings of the National Academy of Science, came out of a collaborative effort of polar researchers from a number of institutions, including the University of Illinois at Chicago, Montana State University and the University of Colorado. The energy driving bacterial life in Lake Vida, a mostly frozen, brine lake below the Antarctic ice shield, may be derived from chemical reactions between the salt water and the underlying, iron-rich rock, researchers said. Conditions at Lake Vida are similar to habitats on Mars and are believed to be present elsewhere in the solar system, creating a potentially new framework for evaluating the likelihood of extraterrestrial life and how it might be sustained. “It can tell us about the origins of life on earth and it also educates us about looking for life elsewhere,” said Peter Doran, principal investigator with the Lake Vida project and environmental sciences professor at the University of Illinois at Chicago. Researchers analysed cores lifted from Lake Vida during expeditions in 2005 and 2010. Microbiologist Christian Fritsen, a co-author of the paper and Professor at the Desert Research Institute in Nevada, said an examination of the cores showed a lake six times saltier than sea water with an average temperature of 8 degrees Fahrenheit (-13° Celsius) and the highest nitrous oxide levels of any natural water body on Earth. Researchers had expected little or no life under such extreme conditions, Fritsen said. “When I first looked down the microscope for bacteria, there was so much more than I ever imagined. It was a world we hadn’t quite expected,” he said. The microbes in the isolated lake contain representatives from eight major bacterial groups, suggesting a complex ecosystem instead of a remnant population of a single life form, the research shows. — Reuters
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THIS UNIVERSE
Does every planet in the universe orbit around a star? I suppose a planet is by definition supposed to be the junior of or tied to some celestial body. This body can most obviously be a star. It might be only a neutron star, even a black hole. Recently, I read a story about discovery in which a planet seemed to be roaming the universe alone. I am not sure about the veracity of this claim. In some sense, thinking of a planet without a star is like thinking of a child that is not related to any parent. Perhaps that is not quite true because children are sometimes cast off to live by themselves, by social or physical calamities. I find it difficult to think of a planet (or for that matter even a star) to be entirely alone because of parental or familial necessities, even in the celestial world. Can we charge a mobile phone battery in vacuum? I do not know whether you have sent me a tricky question, but I do know that there are batteries carried by satellites and these are continuously charged by batteries that are kept charged by solar power. I suggest that satellite batteries cannot be members of a species entirely different from those used in solar cells. But I might be wrong in some essential way.
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Scientists make wheat genetic code breakthrough LONDON: Scientists from Britain, Germany and the United States have unlocked key components of the genetic code for wheat, helping to create varieties that are more productive and better able to cope with disease, drought and other crop stresses. The identification of around 96,000 wheat genes, and insights into the links between them, comes just two years after UK researchers published the raw data of the wheat genome. Sea snails show impact of acidic ocean LOndon: The shells of some marine snails in the seas around Antarctica are dissolving as the water becomes more acidic, threatening the food chain, a study published in the journal Nature Geoscience said. Oceans soak up about a quarter of the carbon dioxide released into the atmosphere each year and as CO2 levels in the atmosphere increase from burning fossil fuels, so do ocean levels, making seas more acidic. — Reuters |
Insects dominate the animal kingdom, both in terms of numbers and variety. According to a rough estimate, insects constitute 90 per cent of the animal kingdom. These six-legged animals, which have been living on earth for more than 250 million years, are very successful in adapting to life and have exploited all kinds of environmental niches, ranging from snow-clad mountains to tropical forests and from deserts to rainforests.
