What Makes A Bug A Pest?

It seems it's all in the guts. Latest Japanese studies refine what is a pest and what is a bug. Depends on the micro-organism in their stomachs.

Writing in the latest issue of the Proceedings of The Royal Society B: Biological Sciences, the researchers said the finding sheds new light on the evolution of pests and may offer fresh approaches to controlling insects that harm livestock and crops.

The team worked on two very closely related species of stinkbugs in Japan - the Megacopta punctatissima, which is a pest of soybean and other crop legumes, and the Megacopta cribraria, that hardly causes any agricultural problems.

After the scientists switched the gut bacteria between the two species, the non-pest species thrived and reproduced prolifically on soybean plants in their laboratory.

The pest species, meanwhile, suffered sharply reduced egg-hatch rates and higher death rates of its nymphs, or larvae -- the very problems that the non-pest species used to face.

"We experimentally exchanged the gut bacteria between the species ... and we found the non-pest species performed very well after the transfer of the symbiont (symbiotic bacteria) and the pest species performed very poorly," Takema Fukatsu of the National Institute of Advanced Industrial Science and Technology said in a telephone interview.

"This indicates that the symbiont determined the pest status of the host stinkbug."

Fukatsu and his colleagues are now analyzing the bacteria found in the two species of stinkbugs.

"We suspect that some mutation may have occurred in their (gut) bacteria and we hope to find the difference between them. In this way, we hope to understand the molecular mechanism underlying what makes a pest and what makes a non-pest," he said.

Looking ahead, Fukatsu hopes their research will have practical applications.

"This molecular mechanism can be used for pest control," he said.