STUDY: Honeybee Pheromones Safely Repel Elephants
A new study shows that alarm pheromones emitted by honeybees safely repelled elephants at South Africa’s Greater Kruger National Park. The study was led by University of Hawai‘i at Mānoa insect ecology specialist Mark Wright.
The findings offer a new strategy for preventing the world’s largest land animals from destroying crops or causing other damage in areas where humans conflict with elephants, said Wright, lead author on the study published in the July 23, issue of Current Biology.
Working with colleagues from the Balule Nature Reserve, University of South Africa, ISCA Technologies and Elephants Alive in South Africa, Wright tested a slow-release formulation that uses two of the two dozen compounds found in the pheromone released by African honeybees when they perceive a threat to their colony. The chemicals alert guard bees to mount a counterattack.
“Elephants have sensitive tissue around their eyes, ears and inside their trunks and hate to be stung,” said Wright, a faculty member in the College of Tropical Agriculture and Human Resources’ Department of Plant and Environmental Protection Sciences. “With their acutely developed sense of smell, African elephants may have either evolved or learned behavioral responses to the scent of the bees’ alarm pheromones.”
Wright, who also explores pheromones as control agents for agricultural pests in Hawai‘i, identified two of the honeybee pheromones that elicit stronger attack responses and contacted California-based biotechnology company ISCA Technologies. ISCA produced the synthetic pheromone mixture and dubbed it SPLAT™.
Scientists applied the pheromone formulation to white socks, which were weighted with rocks and hung from broken tree branches no more than a meter off the ground around water holes frequented by African bush elephants. They observed 66 encounters in December 2017 and February 2018. Most of the elephants that came near the formulation exhibited signs of increased alertness and uncertainty before moving calmly away. In the same timeframe, elephants either ignored similar untreated socks or approached the controls, picked them up or even tried to taste them.
“Our results complement previous studies which demonstrated that active bee hives can deter elephants,” said Wright. Some farmers in Africa place active bee hives along their fence lines to protect crops from elephants, but there are logistic issues with maintaining the large numbers of bee hives needed to protect extensive fence-lines, such as those bordering large national parks.
The need for safe elephant management strategies has become more pressing as expanding human populations in Africa and Asia create larger areas where human-elephants conflicts occur, sometimes with tragic results. People have been trampled to death and their crops are destroyed, intensifying calls for elephant culling programs.
Future studies will pursue the optimal chemical blend and determine whether elephants become inured to the scent in the absence of live bees. “We hope to expand this work to develop additional tools for sustainable passive management of elephant movements, to augment the current approaches used,” said Wright, who is from South Africa and has done previous work on insects and trees in the country’s extensive nature preserves.
ISCA conducts research, develops and commercializes products that use pheromones and other naturally-occurring compounds that manipulate animal behavior to control insect pests without the need for area-wide spraying of toxic pesticides. This study breaks new ground by showing that synthetic pheromones have potential as tools to safely manage a large mammal species as well, company officials noted.