Impact of fires on cockroaches

While there may be some truth to the story that cockroaches can survive radiation following a nuclear explosion, scientists have found cockroaches can struggle to return to burnt areas following severe bushfires.

Dr Heloise Gibb, Associate Professor at La Trobe University’s Department of Ecology, Environment and Evolution, says the largest of several native cockroaches surveyed in Victoria’s Kinglake-Murrindindi region had trouble recolonising the area six years after the Black Saturday bushfires.

‘We found good evidence that one of eight species we collected – notably the biggest one –appeared to be more sensitive to fire,’ said Dr Gibb. ‘The red-legged litter runner, which is about 3 cm long, had trouble moving from the fire edge back into the centre of the burned area.’

Invertebrates make up a third of a forest ecosystem. Along with millipedes, earwigs, springtails, and various beetles, cockroaches are a group of detritivores – species that break down bark, leaves, and other natural litter.

‘Detritivores are good for the ecosystem, because they break down leaf litter so there’s less fuel for future fires,’ said Dr Gibb. ‘If detritivores don’t bounce back, we could get bigger and more frequent fires.’

In a paper published in the latest issue of Austral Ecology with colleagues Ms Kate Arnold and Dr Nick Murphy, Dr Gibb said that climate change has the potential to compound the problem. ‘If climate change increases the frequency or severity of fires, you can have a positive feedback where these communities don’t have time to recolonise before the next bushfire, leaving more fuel.’

Dr Gibb said some species, such as tyrant ants, thrive after fire due to the open habitat being suitable for a short time, and she didn’t find evidence other cockroaches had been impeded. ‘The habitat had recovered 6 years after the fire, so other species of cockroach recovered quite well.’

Dr Gibb is a member of the Ecological Society of Australia, the peak group of ecologists in Australia with over 1100 members from all states and territories.

Post-fire recovery of litter detritivores is limited by distance from burn edge, is published in the latest issue of Austral Ecology (http://onlinelibrary.wiley.com/doi/10.1111/aec.12404/abstract).

Photo: Trilobite cockroaches

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