Learn How Insects Smell

Insects do not have a sense of smell per se, in the way we define it. They respond to chemicals in their environment like humans and higher mammals do, but are not equipped with a nose, nostrils, and smell receptors. Rather, a new study has revealed, they have specialized proteins that perform about the same role. The tiny molecules are located on their antennae, as evidenced by an investigation conducted on silkworm moths. These proteins make the insect sensible to pheromones, chemical triggers in its environment that have been proven to influence its behavior for a long time, the BBC News reports.

The science team behind the new research used the United Kingdom-based Diamond Light Source synchrotron to resolve the structure of the tiny protein, which was the 100th analyzed at the facility. Experts from Rothamsted Research and the University of London collaborated for the investigation, which aims at discovering new ways of creating insect repellents and pest-control mechanisms. The protein could only be deciphered at Diamond because the facility was able to generate intense electron beans that could probe structures down to their molecular level.

Having studied the structure of the protein in great detail, the UK team was able to accurately determine the precise location at which the pheromone molecule binded to it. “We know that [the moth's] odorant binding proteins pick up pheromones at pores on the outside of their antennae and carry them through a watery layer to nerve endings,” Rothamsted senior researcher Dr. Jing-Jiang Zhou, who has also been the leader of the study, explains. The Head of the Insect Molecular Biology Group, Professor Linda Field, says that precisely how the pheromones bind to the molecules is still something of a mystery, and that more studies are required to infer the correct mechanisms.

“We know they have to bind [together] before they trigger a reaction at the receptor, but looking at how they interact is difficult,” she says, quoted by the British news agency. The X-ray images made possible by Diamond revealed that the very structure of the protein changed when exposed to the common insect pheromone bombykol. “In the long term we want to find how this [binding] works and to block it. My research team is working on mosquitoes and aphids to develop systems to protect both crops and humans,” Field adds.

“It's not just the farming community which stands to benefit from this work. These new insights will be fed into the development and refinement of biosensors where detection sensitivity is paramount – in areas like blood tests,” Zhou concludes.