Evaluation of volatiles from ethnobotanical plants as attractants for the honey bee swarms in Kenya

Abstract

Apiculture provides better livelihoods for about 144,000 men, women and youth in Kenya. However, various challenges and barriers are available that prevent the industry from flourishing. One of these challenges is the low hive colonization rate reported by Kenyan beekeepers, who mainly depend on swarm catching to increase colony numbers within their apiaries. Many different traditional plants are used to attract bee swarms, although they have not been tested and compared scientifically with the most used and cost-effective bait in Africa, the beeswax, for improving swarm catches. To fill this knowledge gap, an ethnobotanical survey was carried out in Kenya to gain an in-depth understanding of traditional apicultural practices used for hive baiting to attract swarms. Additionally, the volatile composition of traditional plants used as swarm lures was examined using gas chromatography–mass spectrometry (GC–MS), and their effectiveness in catching swarms was evaluated in comparison to beeswax in the field. The survey results revealed that Ocimum kilimandscharicum, Cymbopogon nardus and Elaeodendron buchananii are the three commonly used traditional plants for baiting, chosen based on their aroma, abundance, ease of processing and durability. Notably, the volatiles emitted by O. kilimandscharicum plus beeswax attracted significantly two and half-fold more bee swarms than the control (beeswax alone), whereas those of E. buchananii were the least attractive and similar to those of the control. These discrepancies may be partly due to the presence of small amounts of geraniol and citral in the essential oils of O. kilimandscharicum, which are characteristic compounds of the Nasonov gland pheromone from workers honey bees known to attract bee swarms. Overall, our findings suggest that adding O. kilimandscharicum to beeswax may significantly enhance bee swarm catches in the field.