Studies on pheromones in insects have fascinated scientists in many fields for decades. Awareness of these chemicals and their importance in the lives of insects goes back several decades. However, scientists have made great leaps forward in understanding their uses recently and have even begun to suggest ways in which pheromones might be used by humans to control insect populations in more ways than one.
Insects emit traces of chemicals at various points throughout each day of their lives. Scientists have discovered that these chemical traces vary in composition and quantity. They serve as a form of communication. From a human viewpoint, it might appear as a substitute for language. If the amount of information that insects can share based on movement and sound is limited, the amount of information that they can share with chemical scents is apparently much greater.
To date, scientists have determined that insects use pheromones for several purposes or signals. Signaling sexually reproductive readiness is obviously one of the most important uses of pheromones. They can also be used to signal locations, mark trails, send various alerts and cause swarming behavior.
Attracting mates is one of the most important functions of pheromones in insects. Due to the importance of this emission, the sexual pheromones of insects are extremely potent and effective. In the 19th century, a French naturalist took extensive notes on the phenomenon. Shortly after the emergence of a lone female moth from her cocoon in his laboratory, his home was suddenly awash in male moths.
After years of research, the naturalist determined that it must be a smell rather than a sound or some other form of signaling that was drawing the moths to this female and others on whom he experimented. He correctly speculated that this work would have significant value for people in the future. The production or inhibition of sexual pheromones could obviously play a role in controlling insect populations.
A Delicate Mixture - Initial attempts to produce or reproduce copies of these pheromones failed disappointingly for decades. The simple mixture of certain chemicals in a laboratory did not seem to evoke the same reactions in insects that production of the very same chemicals by their fellow creatures did. In the 1960s, while studying an aggregation pheromone in bark beetles, a Stanford scientist discovered that it took a specific mixture of these chemicals in order to bring about the desired behavior in the beetles.
The ability to create and mix chemicals properly in order to imitate pheromones has led to several uses in human attempts to deal with insects. The use of sexual pheromones enables the production of insect traps for purposes of extermination. However, greater understanding of pheromones also allows scientists and other to monitor their production and so determine when to act against insects. Farmers monitor the quantity of pheromones present in a crop in order to spray insecticide just as bugs are emerging from their eggs but before they can cause devastation.
Other uses involve the emission of the right chemical mixtures in areas where insects are known to breed. By offsetting the effects of insects’ seductive scents or disrupting them with other smells, farmers can reduce populations before they ever pose a threat to crops. Such attempt shave been shown capable of reducing the number of successful matings in insect populations to less than five percent.
So far these are still crude uses of pheromones. Researchers hope to attain a greater understanding of these chemicals and learn how to use them to monitor and adjust insect activity at an even finer level. As insects become resistant to agricultural pesticides, the need for a new tool to protect human food sources grows greater. Such pheromone-based tools would also have the additional appeal of not posing any threat to the people who eat the food so protected.