Who doesn’t love the smell of earth after a rainfall? It turns out humans aren’t the only ones who appreciate this earthy aroma. Many people think it’s the smell of the soil, but it’s actually a scent called petrichor. This smell comes from tiny bacteria in the soil called streptomycetes, which produce a compound called geosmin.
Interestingly, while geosmin can be toxic to some species, others, like certain insects, associate it with food. Researchers have studied this by using tiny electrodes to monitor how sensitive these insects’ antennae are to geosmin. When given two paths in a Y-shaped tube, these insects almost always followed the invisible scent trail of geosmin.
Scientists believe that insects benefit from nibbling on the bacteria colony, and in return, they help the bacteria spread by carrying their spores to new locations. This relationship is similar to how bees help flowers by spreading pollen. This mutually beneficial relationship helps the bacteria survive in poor soil conditions. Isn’t that interesting?