To chirp or not to chirp, that is often the question for male crickets. Why? Because chirping can bring love -- or death.

The chirps of crickets are love songs that males sing to lure females, but charping can also lure doom, attracting parasitic flies that infest crickets with larvae, new research shows.

The parasites, called Ormia ochracea, burrow into their hosts and after a week or so of feeding on organs, tear their way out, killing the cricket as they emerge.

Researchers have been aware of this for a long time. They even know it has resulted in the wings of one species of cricket found in Hawaii to evolve to the point that they cannot make the traditional mating sound.

But recent research has found the danger posed by the parasites can dramatically alter how males sing and females respond when parasites are around.

"It's a complex tradeoff we see here. If you're a male and don't sing, you're less likely to get females but more likely to live longer, and if you do sing, you attract both females and parasites," explained animal behaviorist Jane Brockmann at the University of Florida at Gainesville.

"There's no free lunch, I guess," Brockmann told LiveScience.

In experiments with wild crickets native to northern Florida, Brockmann and her colleague Manuel V��lez captured males, placed them in containers in the field, and recorded them during the spring and fall. They also surveyed free singing males in a pasture during both seasons.

In northern Florida, the parasitic flies are present only in the fall. The researchers found cricket songs apparently followed this schedule -- 75 percent of the captured males sang in the spring, compared to only 43 percent in the fall.

Female crickets captured either during the spring or fall that had recordings of male songs played at them revealed similar findings.

During mating, female crickets can be quite aggressive, actually mounting the males.

"The spring females are extremely eager," Brockmann said. "The minute they hear a male singing, they race over to the speaker."

But the fall females are much more cautious.

"They take longer and seem reluctant to approach the speaker," Brockmann said, suggesting they are trying to avoid becoming targets for the flies themselves.

Not all of the findings were clear-cut. Often, male crickets never sang, but nevertheless found mates by simply wandering about until they encountered females.

In addition, while fewer males sang in the fall, the ones that did sang far longer. This placed those males at even greater jeopardy of becoming infested, but Brockmann suggested it could also help male singers to mate far more often.

In other words, singing may be dangerous, but its benefits could at times outweigh both its risks and the benefits of not singing.

These findings shed light on the powerful conflict between natural selection pressures, or the capability to survive, and sexual selection pressures, or the capability to mate.

"We're interested in understanding how animals adapt in the face of these pressures, because it's very difficult to predict what the outcome will be," Brockmann explained.

The researchers reported their findings in the November issue of the journal Ethology and the August issue of the journal Animal Behaviour.

Source:Xinhua/Agencies