Study Reveals Why Cockroaches Are Constantly Grooming Themselves
Besides being annoying, cockroaches and self-absorbed narcissists now have another thing in common: both spend a lot of time grooming themselves.
However, unlike vain egotists who spend half their time in front of mirrors being utterly obsessed with themselves, insects like roaches have a more practical reason for taking care of their looks. A new study published Monday in the journal Proceedings of the National Academy of Sciences found that insects constantly groom themselves to keep their senses sharpened.
Researcher Coby Schal, an entomologist at North Carolina State University, found that insect grooming, specifically antennal cleaning, helps remove both environmental pollutants and chemicals produced by the insects themselves.
The findings reveal that incessant self-grooming helps insects maintain their acute olfactory senses, which are responsible for a variety of functions like finding food, sensing danger and detecting mates for reproduction.
The latest study consisted of a simple set of experiments for researchers to understand what material the insects were trying to remove from their antennae, where this material was coming from and the difference between how the function of a groomed and un-groomed antennae.
After a series of experiments on American cockroaches, researchers found that the incessant insect grooming served to clear the tiny, microscopic pores on the antennae, which serve as channels for chemicals travel to reach the insects' sensory receptors for olfaction. The cockroaches in the study clean their antennae by using their forelegs to place the antennae in their mouths, which they use to systematically clean every segment of the antenna from base to tip.
While both volatile and non-volatile chemicals collected on the un-groomed antennae of cockroaches, the study revealed that there was a significant accumulation of cuticular hydrocarbons or fatty, candlewax-like substances secreted by the roaches themselves to protect against water loss.
"It is intuitive that insects remove foreign substances from their antennae, but it's not necessarily intuitive that they groom to remove their 'own' substances," Schal said in a news release.
Researchers also tested how well roaches how well groomed and un-groomed cockroach antennae detected the scent of a known sex pheromone compound and found that insects with cleaned antennae responded to these odors significantly more quickly than those with un-groomed antennae.
Investigators also conducted experiment son carpenter ants, houseflies and German cockroaches, and found that while the different insects groomed differently, the experiments showed that ants and flies also accumulated more cuticular hydrocarbons when their antennae went un-cleaned.
"The evidence is strong: Grooming is necessary to keep these foreign and native substances at a particular level," Schal concluded. "Leaving antennae dirty essentially blinds insects to their environment."
Shal and his team said that the latest study might even explain why certain types of insecticides work more effectively than others. Researchers explain that an insecticide midst or dust that accumulates on a cockroaches antennae would be more effective than residual insecticides that penetrate the thick cuticle because the pesticide would be ingested by the roach almost immediately due to their habit of constant grooming.