A bug's life is tailor-made for survival, scientists say
Release Date 01 September 2009
Scientists have pinpointed why insect life is so varied - because plant-eating bugs stick to their own tiny neighbourhoods to reduce the chances of being eaten.
Insects have adapted to live in particular circumstances - such as the leaf or root of a plant at a particular time of year - to limit their number of potential predators. Researchers at the Universities of Reading and Edinburgh say this helps explain why the creatures have diversified to account for one-third of all animal species.
The study has found that bugs which live in similar circumstances are often attacked by the same predatory insects.
Different parts of a single tree, at various times of year, can feature struggles between many plant-eating insects and their enemies. This helps to explain why, for example, as many as 800 species of insects may be found in one English oak tree.
The study focused on gallwasps - tiny wasps that live in oak trees, in homes known as galls, and showed that their galls provide defence against their enemies. Each gallwasp lives in a particular type of structure, in a specific place on a distinct type of oak at a certain time of year, and the circumstances influence which predators are able to attack.
The gallwasps' enemies have evolved countermeasures to some gall defences, but not all - the insects are engaged in an evolutionary arms race that has lasted for at least 40 million years.
Professor James Cook, from the University of Reading's School of Biological Sciences, said: "Insects make up much of the biodiversity on land, so it's vital to understand how their communities are put together. We have shown that these communities evolve in predictable ways to the networks of species interactions between plants, insect herbivores and insects that eat these herbivores. Our work also shows that, in evolutionary terms, herbivores can both 'run and hide' but natural enemies are always 'chasing' them."
Notes to editors
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The research was carried out by the University of Edinburgh, University of Reading and the Centre for Ecology and Hydrology, together with researchers in Hungary. The study was funded by the Natural Environment Research Council and published in PLoS Biology.
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