Saturday, May 25, 2013
Cockroaches lose their 'sweet tooth' to evade traps
By Victoria Gill for BBC News
24 May 2013
A strain of cockroaches in Europe has evolved to outsmart the sugar traps used to eradicate them.
American scientists found that the mutant cockroaches had a "reorganised" sense of taste, making them perceive the glucose used to coat poisoned bait not as sweet but rather as bitter. A North Carolina State University team tested the theory by giving cockroaches a choice of jam or peanut butter. They then analysed the insects' taste receptors, similar to our taste buds. Researchers from the same team first noticed 20 years ago that some pest controllers were failing to eradicate cockroaches from properties, because the insects were simply refusing to eat the bait.
Dr Coby Schal explained in the journal Science that this new study had revealed the "neural mechanism" behind this refusal. In the first part of the experiment, the researchers offered the hungry cockroaches a choice of two foods - peanut butter or glucose-rich jam [known as jelly is the US]. "The jelly contains lots of glucose and the peanut butter has a much smaller amount," explained Dr Schal. "You can see the mutant cockroaches taste the jelly and jump back - they're repulsed and they swarm over the peanut butter." In the second part of the experiment, the team was able to find out exactly why the cockroaches were so repulsed. The scientists immobilised the cockroaches and used tiny electrodes to record the activity of taste receptors - cells that respond to flavour that are "housed" in microscopic hairs on the insects' mouthparts "The cells that normally respond to bitter compounds were responding to glucose in these [mutant] cockroaches," said Dr Schal. "So they're perceiving glucose to be a bitter compound. The sweet-responding cell does also fire, but the bitter compound actually inhibits it - so the end result is that bitterness overrides sweetness." Highly magnified footage of these experiments clearly shows a glucose-averse cockroach reacting to a dose of the sugar. "It behaves like a baby that rejects spinach," explained Dr Schal. "It shakes its head and refuses to imbibe that liquid, at the end, you can see the [glucose] on the side of the head of the cockroach that has refused it."
The process of natural selection would strongly favour any chance genetic change that caused a cockroach to avoid the bait and therefore death. Since individuals with the trait would have a greater chance of surviving and reproducing, their descendants with the trait would in time replace those that lacked the trait in the cockroach population. This is the same process that has led to the evolution of antibiotic resistance in disease-causing bacteria, and warfarin resistance in rats. The discovery of natural selection was one of the greatest scientific breakthroughs of all time and this year sees worldwide celebrations commemorating the 100th anniversary of the death of Alfred Russel Wallace, the naturalist who co-discovered natural selection with Charles Darwin in 1858.
Dr Elli Leadbeater from the Institute of Zoology in London said the work was exciting. "Usually, when natural selection changes taste abilities, it simply makes animals more or less sensitive to certain taste types. For example, bees that specialise on collecting nectar are less sensitive to sugar than other bees, which means that they only collect concentrated nectar. Evolution has made sugar taste less sweet to them, but they still like it. In the cockroach case, sugar actually tastes bitter - an effective way for natural selection to quickly produce cockroaches that won't accept the sugar baits that hide poison." Dr Schal said this was another chapter in the evolutionary arms race between humans and cockroaches. "We keep throwing insecticides at them and they keep evolving mechanisms to avoid them," he said. "I have always had incredible respect for cockroaches," he added. "They depend on us, but they also take advantage of us."
[Another example of Evolution in action alongside the increase in anti-biotic resistance that is causing us more and more headaches at the moment. Of course when you think about such modifications are inevitable. We humans are just another selection force on many creatures we come into contact with. Some of them have been or will be pushed into extinction because of our actions. Some will be pushed to the boundaries of the world where we have little or no interest and thrive there. Some will evolve strategies to combat out attempt to control or kill them and some will fight back – with varying levels of success. Some, probably viruses or bacteria, will become much stronger because of our efforts to eradicate them and could eventually destroy us because of that. All the more reason to understand evolutionary processes and act accordingly. For without that level of understanding we may unwittingly bring into being something that could finish us off.]
Friday, May 24, 2013
Thursday, May 23, 2013
Just Finished Reading: A Brief History of Britain (1485 – 1660) - The Tudor and Stuart Dynasties by Ronald Hutton
The very first thing I thought when I picked up this book was that it looked a bit thin. How, I thought, can the author cover and do justice to 175 years of British (not just English!) history in 290 pages. It’s not exactly as if those years were times of quiet contemplation after all! Only the large scale we had the end of Plantagenet rule with the death of Richard III at Bosworth and the rise of the Tudors who are arguably the most famous and loved of our monarchs. Both Henry VIII and his daughter Elizabeth I tower above so many other people during the Early Modern period that it’s difficult to see anyone else – though some very impressive people are scattered through their time. Then there’s the English Reformation caused by Henry’s split with Rome and the inevitable conflict between Catholic and Protestant both at home and abroad including the threat from Catholic Spain which sent her famous Armada against us. Of course Elizabeth being the ‘Virgin Queen’ didn’t leave an heir and had to be followed by James Stuart in 1603 and Charles Stuart in 1625. In the following 17 years tensions between King and Parliament led, in 1642, to a long and bloody Civil War and finally to the declaration of a republic, known as the Commonwealth in 1649 led by Oliver Cromwell who has been a figure of hate and admiration ever since depending on the political stance (and nationality) of the people involved. With the collapse of the Commonwealth in 1660 Charles II was restored to the throne in a matter of weeks and the brief experimentation with republicanism passed into history.
Wednesday, May 22, 2013
Tuesday, May 21, 2013
Monday, May 20, 2013
My Favourite Movies: Interview with the Vampire
As you will know by now I’m a fan of vampires in most genres – especially movies and how could I avoid this one. Starring some of my favourite actors and adapted from one of my favourite series of books by Anne Rice.
Telling the story of Louis (played by and large in an understated manner by Brad Pitt) who, on losing his wife and child in 18th Century New Orleans, invites death at every opportunity. Enter Lestat (played in over-the-top fashion by, I think, somewhat of a miscast Tom Cruise) who offers him death or eternal life as a vampire. Louis chooses life and regrets it for the next 400 years. Telling his story in modern day San Francisco to struggling author Dan Malloy (played in typical fashion by Christian Slater) he relates his struggles with immortality – whilst still feeling guilt with every life he takes – the ‘making’ of the child vampire Claudia (in one of Kirsten Dunst’s early roles), their journey across Europe looking for more of their kind and his final meeting with the vampire Armand (played with real style by Antonio Banderas) and the violent fall-out of their encounter. Beautifully filmed and told with style (it’s a Neil Jordan film after all) I found this movie a delight to watch. Despite not exactly seeing Cruise as Lestat (Stuart Townsend played him much better in Queen of the Damned I thought) he was often suitable frightening, perverse and borderline scary just as a creature without apparent limits would be I guess. Dunst, then aged a mere 12 years old was amazing as the woman trapped forever in a child’s body because of Lestat’s desire to keep Louis with him through his love for her.
Full of sumptuous locations, sudden violence, plenty of blood and a fair bit of gallows humour this is a treat for any vampire lover out there. Since its release in 1994 I don’t think it’s aged at all and seems just as fresh as it did back then. These guys (and girl) are proper vampires. They kill whenever they need to or simply want to. By and large, once Louis gets over his guilt trip, they see humans as food to be consumed and discarded as required. Sometimes they play with their food and sometimes they dispatch it without another thought. They think of themselves as superior to mere mortals and revel in their abilities – just as proper vampires should. They’re not nice people (even Louis) and don’t pretend to be anything other than what they are – predators. They don’t glow in sunlight, they die. OK, Rice messed about with some of the folklore – crosses, stakes and holy water have no effect on them – but the rest is pretty much spot on and traditional. It’s definitely how I like my vampires – carnivores rather than wimpy vegetarians!