A single locust is just bigger than a paper clip. But when these solitary critters attract others into a growing swarm, billions of locusts wind up flying together, forming a moving carpet that can block out the sun and strip the landscape of plants and crops.
Giant swarms like this have devastated large swaths of crops in Africa and Asia since January, threatening food supplies for millions. But until now, scientists weren’t sure what causes the insects to come together and abandoning their solitary lifestyles.
A study published Wednesday in the journal Nature pinpointed the trigger: Migratory locusts respond to a pheromone called 4-vinylanisole (4VA). 4VA is specific to that one type of locust, but the finding could offer a way to control many devastating swarms, including those wreaking global havoc this year.
The study authors suggest using 4VA to corral locusts into areas in which they can then be killed en masse with pesticides. This may not sound like the best way to get rid of locusts, but considering how quickly locusts destroy crops in Asia and Africa, it seems like it might be necessary. However, scientists do believe that there may be another way to stop locust swarms, which is by figuring out a way to stop locusts from detecting 4VA at all.
Locusts detect the pheromone via their antennae; the molecules attach to an olfactory receptor. So the researchers genetically engineered locusts to lack that receptor and found that the mutant locusts were less attracted to 4VA than their wild counterparts. This suggests that it could be possible to make locusts blind to their own scent, thus stopping swarms from forming.