It turns out that not all colonies of Madagascar hissing cockroaches harbor the mites, a species called Gromphadorholaelaps schaeferi. Researchers do not know why that is. But the cockroaches that do harbor mites also harbor fewer molds on their bodies.
In the study, female cockroaches with mites had 64 percent fewer fungal colonies than those lacking mites. In males, the difference was 31 percent, and in nymphs, or younger and smaller cockroaches, there were 24 percent fewer fungi.
To ensure the mites were responsible for the reduction in fungi, the researchers tested colonies with and without mites, but also removed mites from colonies that originally had mites and added mites to cockroaches that didn't initially harbor any mites. In all cases, the presence of mites resulted in lower levels of mold.
The most commonly found mold species found on the body surfaces of young and adult Madagascar hissing cockroaches were Rhizopus, Penicillium, Mucor, Trichoderma and Alternaria, several of which are listed by the Centers for Disease Control and Prevention (CDC) as common indoor molds.
"The presence of the mites caused a reduction in all fungi on the surface, not just a select few kinds of fungus," said Jay Yoder, a professor of biology at Wittenberg University and lead author of the study.
About 20 to 25 mites live on each adult cockroach. The scientists experimented by adding more mites to the insects' surfaces, but found that more mites didn't result in a more significant reduction in molds.
"The number on each insect is based on the food available," Benoit said.
In captivity, Madagascar hissing cockroaches thrive on dog food and fruit. Benoit said they tend to slobber on themselves when they eat, leaving saliva and organic d
|Contact: Joshua Benoit|
Ohio State University