A new study from researchers at North Carolina State University found that cockroaches communicate with each other via the gut bacteria located in their feces. The team of researchers discovered a variety of fatty acids that contribute to pheromone production were in the feces, which serve as a means of attracting other roaches.

"When you lose the gut bacteria, you lose the aggregation pheromones," Coby Schal, co-author of the study, said in a press release.

More than 40 different pheromones were discovered in the feces of German cockroaches; Schal and his colleagues found that those without gut bacteria lacked 12 of these compounds and only had very small amounts of 24 of them. Furthermore, they also tested nymphs, which are newborn roaches, and compared the results to older roaches both individually and in groups. The results were the same, with aggregation occurring in those with compounds in their feces and little aggregation found in those with low or no levels of the compounds.

"The chemical compounds seem especially essential for nymphs," said lead author Ayako Wada-Katsumata. "It's important for nymphs to determine a safe place, and these pheromones help do just that."

The researchers followed up on their findings by using gas chromatography and mass spectrometry techniques to narrow the 40 attractive compounds down to the six that where the strongest attractants.

"Aggregation pheromones may drive colony fidelity," Schal said. "Different gut bacteria create different chemical profiles of aggregation pheromones, but many of these compounds overlap, depending on the food available to roaches. This suggests that aggregation is plastic, as compounds can be mixed and matched for different groups of roaches, depending on their environment."

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