Car exhaust keeps moths from smelling the roses

A study in the journal Science found that the smell of car exhaust and other urban emissions makes it harder for moths to find flowers. It turns out that moths are not really confusing one for the other. Instead, one smell is altering the representation of the other smell in the moth's brain. Why does this happen? What is common between fuel emissions and flower fragrances? The answer is that several of the volatile organic compounds (VOCs) in fuel emissions are derivatives of benzene, as are VOCs in the smell of flowers. For example, benzaldehyde, a compound in the plume of the Sacred Datura flower, is formed by substituting a formyl group compound for a hydrogen atom in a benzene ring. Toluene, found in fuel fumes, comes from substituting a hydrogen item with CH3. The author of the Science study, Jeff Riffell, told me in an email that this could be why these two compounds, which come from such disparate sources, elicit similar responses in the brains of moth. Click below for the link to my short piece on the study:

http://news.sciencemag.org/plants-animals/2014/06/car-exhaust-keeps-moths-smelling-roses