Elephant Deterrent Made From Bee Pheromones Could Give Farmers a Boost

People turn to squirt bottles to keep cats from countertops and spray a sour apple mist to shoo dogs from tables, but when it comes to stopping elephants from destroying crops, humans have had to get creative. Some desperate African farmers have turned to installing beehives, a costly and tricky last resort that relies on the elephants’ fear of being stung. But a makeover to that method, described in a study published Monday in Current Biology, suggests farmers can instill that fear of bees without relying on the sting.

When hives are disturbed, honeybees shoot out a blend of volatile organic compounds that signal to their buddies it’s time to attack the invader. Scientists believe that years of being stung has taught elephants that when they smell “alarm” pheromones, it’s time to scoot. And so, as the study illustrates, you don’t even really need bees to deter a parade of elephants — you just need their pheromones.

“We hypothesize that they learn to respond to the odor of the pheromones, associating the smell with negative experiences when interacting with beehives,” study co-author and University of Hawaiʻi at Mānoa insect ecology expert Mark Wright, Ph.D., tells Inverse. “Elephants remember negative experiences for a long time, and memory of occasional stings and hive interaction may remain with them for ages.”

Wright and his team knew that farmers had successfully protected their fences with beehives, so they set off to discover whether they could achieve the same deterrent effect with the alarm pheromones alone. The scientists teamed up with the biotech company ISCA Technologies to create a prototype “alarm pheromone” mix. To the human nose, the chemical blend has a strong, durian-like smell, which is likely rooted in the compound isoamyl acetate, the same compound bananas produce when they start to rot.

The blend of pheromones was placed in a slow-release matrix, which was then put inside suspended socks weighed with rocks. These socks, as seen in the photograph above, were hung on branches around Kruger National Park in South Africa, together with decoy socks that had no smell. Just as they thought, 25 of the 29 of the elephants that came across the pheromone-laden socks became alert and uncertain after sniffing them, eventually moving away. The socks that didn’t contain pheromones, however, led curious elephants to try to snack on them.

Notably, the elephants who smelled the pheromones — like the ones in the video below — moved away calmly, suggesting they thought they were in danger of being stung.

A scared elephant could mean danger for a human — and for their herd — so if the pheromone potion is to be used on farms, it’s crucial that it elicits a calm response. In the study, the researchers emphasize “the need for safe elephant management strategies has become more pressing as human populations have grown in Africa and Asia, creating larger areas where elephants conflict with humans by trampling crops or causing other damage.” No one wins when these conflicts erupt. A trampled human or a destroyed field of crops often means that elephants deemed as destructive are killed.

“This work importantly allows us to develop a sustainable management tool,” says Wright. “Human-wildlife conflict is a serious problem and developing sustainable and effective ways to deter elephants from breaking fences and raiding farms is a valuable contribution.”

The effectiveness of the potion hinges on the elephant’s highly developed sense of smell and years of learning how much it sucks to be stung in the soft tissues of their eyes and the insides of their trunks. Elephants, like humans, hate being stung, and have evolved to learn which semiochemicals mean trouble. Humans can smell alarm pheromones, too, explains Wright, but we evidently don’t have the instinct to scamper away. Instead, we’re forced to keep an eye out for a swarm — or deal with the stings.