When humanity’s predilection for perfume meddles with the sense of smell of insects and animals, it can sometimes be fortuitous. Case in point: the discovery that Calvin Klein’s Obsession perfume lures jaguars, tigers, and other big cats to expectant nature photographers and videographers. But meddling with odor receptors of other creatures can prove problematic. For example, the cosmetic and food fragrance 1-methylbutyl 3-methylbutanoate elicits aggressive defense behaviour in hornets. Sometimes people meddle with an insect’s ability to smell sexual pheromones as a means to combat invasive species. In 2007, California’s agricultural industry tried spraying an overwhelming amount of invasive moth species pheromone onto fruit crops because they hoped the signal overload would confuse the male moths and disrupt the species’ mating cycle–a solution that led to serious controversy.
The question that Richard Bolek, a PhD student, and his adviser, Klaus Kümmerer, at the University of Freiburg Medical Center, in Germany, want answered is whether some of the fragrances we use—in perfumes, personal care products, and cleaning agents, which get released into the air or down the drain–are inadvertently interrupting some of the chemical communication networks that benign or beneficial insects and animals rely on.
Is our obsession with smelling nice disrupting networks, such as, say, the fascinating ménage à trois network reported in last month’s Science? In that study, moth larvae (Manduca sexta) feeding on tobacco plants leave behind spit chemicals that isomerize some of the plant volatiles floating out of the munched-up leaf. These isomerized plant volatiles then attract predators (Geocoris), which find the larvae delectable.
Some people’s perfumes, and the fragrance of some bathroom cleaners, certainly drive me to near aggression. Bolek is trying to find out if insects and animals feel the same way. As he pointed out at the EUCHEMS conference this week in Nuremberg, Germany, not all fragrances are biodegradable, and there are three times more fragrances used in laundry and other cleaning products now in Germany than just a few decades ago–fragrances that inevitably end up down the drain or in the air. The project is just getting started: Bolek is currently analyzing levels of fragrance molecules he sampled from hospital waste streams, an experimental setting chosen because hospital administrations keeps track of how much and which brands of cleaning products are used. It’s the beginning of something worth keeping an eye (nose?) on.