By Alice Vincent, Wired UK

Evolutionary biologists have tested to show that it is not only motorbiking bad boys who embody the ‘live fast, die young’ mantra, but also those hard nuts of the insect world, crickets.

In a study looking at the relationship between sexual performance, life expectancy and metabolic rate undertaken by David Hosken and his team, of the University of Exeter, crickets which exert a lot of energy during their lives have been found to die earlier.

Hosken explains in a press release: “Metabolism can be thought of as the burning of fuel that keeps us alive. Metabolic rate is the speed at which we burn the fuel. If we burn it faster we die younger.” Resting metabolic rate is how much energy the body burns off when it is, well, resting; or as Hosken puts it, “the body’s idling speed”. These rates vary amongst different organisms.

From this information, the team reasoned that some crickets will have a “smaller energy budget” than others, so that some will be more tired than others after similar activity. One activity which uses up a lot of energy is crickets’ “advertising of sexual maturity”. or making noisy mating calls by rubbing their serrated wings together. Hosken and his team predicted that the differing impacts of the mating calls on crickets’ energy supplies “could have an impact on lifespan”.

This hypothesis was tested by an experiment with 70 lab-raised male crickets whose mating calls were recorded for 15 hours. The next day, the 10 day old insects were weighed and had their resting metabolic rate assesed by measuring how much carbon dioxide they produced. Crickets with a higher metabolic rate burned more energy and therefore produced more carbon dioxide. They were then left to live out the rest of their days in another container.

As published in Behavioural Ecology and Sociobiology, crickets with a higher metabolic rate died sooner, proving, as Hosken says, that “males that live fast die young”.

Although the team’s prediction was shown to come true, the equation is not quite that simple, as they found no evidence that the effort the crickets put into their mating calls influenced longevity. Hosken says that this may be due to fact that this relationship between physiological performance and behavioral traits is “largely under-explored.”

Image: me’nthedogs/Flickr

Source: Wired.co.uk

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