Science by Email 20 April 2012

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	20 April 2012
News: Sick with loneliness By Patrick Mahony The caterpillars of the large white butterfly have evolved an unusual (and disgusting) defence mechanism. They say there is safety in numbers, but what do you do for protection when you’re left out on your own? Especially if you’re a caterpillar and a hungry bird has its eye on you? Animals have evolved a range of defence mechanisms, from squids that squirt ink to an echidna’s spines. Some animals go to extraordinary lengths to protect themselves: the African crested rat chews and then rubs toxic bark on its fur and allows itself to be bitten in order to poison dogs. The common purpose of these features and behaviours is to prevent one animal becoming another’s dinner. The caterpillars of a species called the large white butterfly have evolved one particularly gross defence mechanism: vomit. The vomit contains semi-digested plant material with chemicals that smell and taste unpleasant to predators, making the caterpillar less appealing to predators. This action comes at a price: research shows that defensive spewing is bad for the caterpillars in the long run. It slows their growth, interferes with reproduction and reduces their rate of survival. New research indicates that the caterpillars are more likely to vomit when alone. When caterpillars are in a large group, they rely more on safety in numbers to protect them from being eaten. When there are more caterpillars, it’s more likely that a creepy-crawly companion will be eaten. When in a group, the caterpillars are also competing for food. A caterpillar that vomits puts itself at a disadvantage compared to others. It’s better for their survival to keep all the nutritious cabbage that forms their diet safe in their bellies. In the animal world, it seems you can always rely on nature to throw up something unusual! More information Caterpillars more likely to vomit alone 10 of the most bizarre animal defence mechanisms Careers link Entomology careers
You will need these materials.   Use the nail to poke some holes in the lid.   Half fill the container with oats or bran and add some potato. Seal the container and observe for a few weeks.   Try this: Life of bugs   You will need Live mealworms (these can be found at pet shops) Potato pieces Plastic container with a lid Nail Oats or bran What to do Use the nail to poke some holes in the lid of the container. Half fill the container with oats or bran and add a piece or two of potato. Add the mealworms to the container. Put the lid on the container. Check on the mealworms every day for 3 to 4 weeks. How do they change? What’s happening? Many insects have a life cycle that consists of distinct stages. The mealworms you start with are the larval stage of this cycle, which hatch from eggs. As the larvae grow, they shed their hard exoskeleton when it no longer fits. Eventually, instead of just shedding their exoskeleton, the larvae turn into pupae. Pupae are largely inactive – at this stage the insects don’t feed or move around much. After a period ranging from days to weeks to months, the adult beetles emerge from the pupae. The adult beetles look very different from the larvae and the pupae. This process where the insect goes through four life stages is called holometabolous metamorphosis. The insect looks very different at different life stages, and in many species they also exhibit different behaviour, eat different foods and live in different habitats at different times. Many insects, including butterflies, flies and beetles undergo this type of metamorphosis. Applications Some insects, such as bees, are beneficial to agriculture as they pollinate a number of food crops. Others, such as fruit flies, are considered a pest as they cause damage to fruit and vegetables. By understanding the different stages of the insect life cycle methods can be tailored to effectively eliminate and manage pests. An example of this is Sterile Insect Technique (SIT). In SIT for fruit fly, pupae are typically treated with radiation. The radiation is not strong enough to kill the pupae, so they hatch as normal. However, the irradiated male fruit flies are infertile (sterile) and cannot produce offspring. Female fruit flies only mate once during their lifetimes. If a female fruit fly mates with a sterile male, her eggs will be unable to develop. By releasing large numbers of sterile males into areas infested with fruit flies, enough females are prevented from reproducing, thus controlling the infestation. By Patrick Mahony Try another Science by Email activity about insects More information Life as a bug Sterile Insect Technique View the online version Quiz questions 1. Which animals belong to the order Lepidoptera? 2. What is muriatic acid more commonly known as? 3. Does sound travel faster in air or water? 4. What significant milestone did the Atlas of Living Australia recently reach? 5. Where might you find chondrules? Did you know? The Australian National Insect Collection is the world’s largest collection of Australian insects. It gains about 100 000 new specimens every year. Websites   See it! Check out these photos of insect eggs. See it! Can you guess which insect leaves which trail? National Youth Science Forum The National Youth Science Forum (NYSF) is a 12 day residential science program for students entering year 12. It runs in January, with sessions in Canberra and Perth. The program includes lab tours, talks and social activities. The program is ideal for students interested in a future career in science, engineering or technology. More information, including how to apply, can be found at the NYSF website. Events National: Critical thinking competition Can you come up with an argument to convince Australia’s Chief Scientist? TechNyou is running a critical thinking competition for those aged 14 and up. To enter, make a video arguing for or against one of the given topics, which include nuclear power, nanotechnology and genetically modified crops. Entries close 1 May 2012. More information can be found on the competition website. Watercraft, Saturday 21 March at 9.00 am on Network Ten Speedboats, paddle steamers, container ships, jet skis and hovercrafts! From hull to bridge and bow to wake, join Dr Rob as he SCOPEs out the science behind watercraft, once again proving that the ordinary becomes extraordinary, under the SCOPE. Next episodes: Thursday 26 April: Sailing Saturday 28 April: Household science Want to have your own episodes of SCOPE to watch whenever you feel like it? Click here to download them directly into your iTunes folder, or go here to download iTunes. Charges apply. Quiz answers 1. Moths and butterflies belong to the order Lepidoptera. 2. Muriatic acid is more commonly known as hydrochloric acid. 3. Sound travels faster in water than air. 4. The Atlas of Living Australia reached its 30 millionth entry. 5. Chondrules are small spheres in meteorites that originally formed from molten material. Researchers from the Australian National University have a new theory about how chondrules formed. Science by Email is a CSIRO publication. The Department of Agriculture, Fisheries and Forestry and bankmecu are proud partners of Science by Email. Editor: Jasmine Leong| Manage your subscription | FAQ

 

 

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