Thursday, 13 July 2017

Stupid Design - Cannibal Caterpillars


Beet armyworms on tomato leaves. A choice of nasty-tasting leaves or juicy sibling!
Plants under attack can turn hungry caterpillars into cannibals

I almost laughed out loud when I read this one. Not only is it a lovely little piece of biology and so easy to explain in terms of genetic evolution but it's also an example of the mind-numbing stupidity of any sentient designer who had to come up with such a design to solve a problem it had designed!

Abstract
Plants are attacked by myriad herbivores, and many plants exhibit anti-herbivore defences. We tested the hypothesis that induced defences benefit tomato plants by encouraging insects to eat other members of their species. We found that defences that promote cannibalism benefit tomatoes in two ways: cannibalism directly reduces herbivore abundance, and cannibals eat significantly less plant material. This previously unknown means of defence may alter plant–herbivore dynamics, plant evolution and pathogen transmission.


Basically, having designed tomatoes and then having designed these caterpillars to eat the tomato leaves, the tomato has had to be redesigned to produce a chemical that stops the caterpillars eating its leaves - and start eating one another instead!

No! Seriously! And creationists assure us that there is evidence of the brilliance and super-intelligence of their putative designer all around us!

In fact, when you examine it in anything more than a superficial, blind and biased way looking for confirmation of bias, almost everything you see in nature turns out to be the product of an unthinking, undirected, unplanned process with no conception of the future and with everything living for the moment.

Sadly, the full text of the paper sits behind an expensive paywall, but a press release from the University of Wisconsin-Madison has the details. The caterpillars, known as beet armyworms are an economically important agricultural pest that feed on a wide variety of crops so a natural defence would be both ecologically sound and economically beneficial.

Because plants are obliged to be sedentary they don't have the range of escape options available to animals so have had to evolve more sophisticated, chemical defences - which is why many plants are poisonous. One of their defences is to produce a chemical 'scream' which serves the same purpose as the scream of a captured animal - it alerts the others to the presence of danger. Plants then respond to this chemical 'scream' by producing substances that deter the herbivore from eating them. This could be a toxin or an unpalatable taste. One such chemical is methyl jasmonate.

In the case of the armyworm, there is already a tendency to resort to cannibalism when food is scarce - because they've eaten it all. This doesn't help the plants that have all been eaten of course, but the tomato plant appears to have induced cannibalism way before that stage and the likelihood was that it was something they were producing in response to attack.

So to test the hypothesis that it was something the tomatoes were producing that was inducing cannibalism, the team devised a simple experiment. They sprayed tomato plants with a range of concentrations of methyl jasmonate as well as a control solution, then they introduce eight caterpillars to each plant and counted the number of caterpillars remaining each day for eight days. After eight days, the amount of plant material remaining was weighed to determine how much had been eaten.

With the control solution and lower concentrations of methyl jasmonate, the caterpillars ate the entire plant before turning cannibal but at the higher concentrations, the plants remained intact and the caterpillars turned cannibal much sooner.

The tomato avoids being eaten and the number of herbivorous predators in the environment get reduced. Any intelligent (sic) design advocate would proudly trumped the brilliance of this solution - until asked to explain why a brilliantly intelligent designer would have designed to problem in the fist place.

Far from the evidence of intelligent design being all around us, what is all around us is evidence of solutions to problems caused by solutions to earlier problems which were themselves problems... etc... Evolution is good at both solving problems and at creating other problems for other things for them to solve - because it doesn't have a plan and reacts only to the here and now.

It's a strange definition of intelligent design for the designer to be continually designing problems to solve its own problems. Not for the first time does the creationist industry seem to be relying on private definitions of every-day words and on the credulity of people who are far from intelligent themselves.

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