Cockroaches had to find a new way to mate due to humans’ attempts to kill them

Males have thought of two ways to get the females again

German cockroach. (Image by Erik Karits from Pixabay)

SAN ANTONIO – Cockroaches have found love in a hopeless place.

A recent scientific study showed that German cockroaches — the nuisance of households across America — have found a new way to mate amid the everyday use of insecticides.

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The study, published on Wednesday in Proceedings of the Royal Society B, states that insecticides use glucose to attract and kill roaches.

But even with their sweet tooth, the roaches have developed a “sensory conflict” called glucose aversion to learn to avoid the poison.

The problem is, well, glucose gets the mood going between male and female roaches.

During courtship, male German cockroaches offer females a “nuptial gift” of a sugary secretion called maltose to expedite copulation.

If the female ingests the fluid, then her saliva rapidly breaks down the maltose to glucose.

Before the glucose aversion, this would allow the male time to “extend his abdomen and grasp the female’s genitalia” as she consumes the sugar.

But the new glucose aversion has seriously ruined the mood for female roaches — therefore ruining mating success.

Female roaches are simply turned off by the sugary gift and leave the rendezvous before the mating can commence, scientists say.

Because we’re talking about roaches here, and because they seem to be immortal, scientists say they have found a way to work around the sexual hardships.

Male roaches now produce more maltotriose, which is more resistant to glucose aversion, the study states. Males also start the mating process faster, before the female can scurry off.

“Results suggest that the two courtship traits emerged in response to the altered sexual behaviour of GA females and independently of the male’s GA trait,” it says. “Although rapid adaptive evolution generates sexual mismatches that lower fitness, compensatory behavioural evolution can correct these sensory discrepancies.”

Scientists added that there was no change in mortality and development in the roaches despite the glucose aversion, except in areas where glucose is a prominent food source.

The origin of the trait is unknown, but scientists said human imposition, like insecticide bait, has led to habit change.

“... Rapid evolution of the sensory system can interfere with other behaviours, and animals must overcome such sensory conflicts,” it says.

Read about the study here.

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About the Author:

Rebecca Salinas is an award-winning digital journalist who joined KSAT in 2019. She reports on a variety of topics for KSAT 12 News.