Pest Obesity?? Here's More On the Fat Cockroach!

by Tanya Thomas on Jul 7 2009 10:46 AM

A British researcher has discovered that obesity isn't the prerogative of humans alone. Apparently, cockroaches can plump on an unhealthy diet.

Patricia Moore, of the University of Exeter, came to this conclusion after studying how female cockroaches change their mating behaviour in response to their diet, specifically what they eat when they are young, as part of a decade's worth of research.

"We already knew that what they eat as adults influences reproductive decisions," Live Science quoted Moore as saying.

However, it was not known how the food consumed by the eternal pests in life shaped these decisions.

To find out, Moore's team picked young female cockroach nymphs, and divided them into two dietary groups.

She revealed that the cockroaches in one group were fed a good-quality balanced diet of protein-rich fish food and high-carbohydrate oatmeal, while the rest were raised on fish food only.

She further revealed that both groups could eat as much as they wanted.

The difference in diets "was not quantity but variety," Moore said.

When the nymphs became adults, the researchers switched the diets of some of them.

Half of the cockroaches raised with good quality diet lost their oatmeal, while half of the bugs fed poorly were promoted to a good-quality diet.

Moore said that 18 days after the switch, the diet control ended. While some of the surviving cockroaches were dissected, she said, the rest were allowed to live on and reproduce.

The researchers observed that while the lifespan of the members of both groups was about the same, the cockroaches on the poor diet were fatter and took longer to mature.

Moore said that the poorly fed bugs were storing up excess fat at the expense of their growth in case their dietary options got even worse.

"This was a surprising result, but it shows the importance of a balanced diet for healthy development," she said

According to her, the effects of unbalanced meals continued throughout the cockroaches' lives, even for the few that were switched to good-quality food.

She and her colleagues observed that females fed on a poor-quality diet were less willing to mate, and less likely to produce offspring.

Such females were also more picky, and spent more time considering possible mates, said the researchers.

Based on the study's findings, Moore concluded: "Poor diets (during early life) have an effect on the way cockroaches respond to their environment and cannot be reset later on."

A research article describing the study has been published in the journal Proceedings of the Royal Society B.