4-Vinylanisole

4-Vinylanisole (4VA)—frequently also called 4-methoxystyrene—is a naturally occurring aroma compound. Among other sources, it is one of the volatile components of the French brandy Mirabelle, which is obtained by fermenting the juice of the mirabelle plum (Prunus domestica subsp. syriaca).

Beyond the brandy connection, 4VA is the center of a more spectacular natural phenomenon. This year, Xianhui Wang, Le Kang, and six collaborators at the Chinese Academy of Sciences (Beijing) reported that 4VA is the culprit responsible for locust swarms, such as those that recently devastated large portions of East Africa.

When solitary migratory locusts (Locusta migratoria) form small groups, they begin to emit 4VA, attracting additional insects. As the locusts aggregate, the 4VA signal becomes stronger, and the swarm grows exponentially. This year’s swarm—some call it a “Biblical plague”—covered thousands of square kilometers, mostly in Kenya and Ethiopia, but also in other African and Middle Eastern countries.

4VA’s aggregation pheromone property might have a positive side. Instead of using pesticides to control the locusts, 4VA could potentially be used as a bait to trap the insects before they begin the swarming process, according to Wang, Kang, et al. The researchers also found that a genetic modification prevented locusts from detecting 4VA signals; but others in the field warn against unintended consequences from this sort of alteration.