Chemical variability in the components of T. vogelii essential oils from eastern Uganda was identified using principal component analysis (PCA) and Agglomerative hierarchical clustering (AHC). Based on the profiles of the compounds of farnesene family three chemotypes were found: farnesol (chemotype 1), springene (β- Springene and α-Springene) and the β-Farnesene were distinctive in chemotype 2 and a mixed variety of farnesol and the Springene. In the three cases, alkybenzenes; o-xylene, m-xylene and ethylbenzene were significant components in the oil. 1,4-dihydroxy-p-menth-2-ene, 5,9-undecadien-2-one, 6,10-dimethyl, and 3-cyclohexen-1-carboxaldehyde,3,4-dimethyl were other prominent constituents. The yields of the essential oils did not vary significantly however the chemical composition varied with harvesting time during the rainy and dry seasons. In choice repellency tests, chemotype 1 and chemotype 2 were more active against Sitophilus zeamais than mixed chemotype. Farnesol was found to be effective only at a higher concentration as a repellent against S. zeamais. However, further study that aims to optimize and standardize the varieties and harvesting period needed for recommendation to smallhold farmers.

Before the green revolution, crude plant materials and plant-extracts were used for crop protection. However, their use was swiftly replaced by synthetic pesticides after World War II due to increased demand for more effective pesticides in intensified farming systems. The 20th century saw a steady increase in the use of synthetic pesticides until the mid-21st century when the world started to realize the negative impact of synthetic pesticides. The increased environmental awareness and the need for safe human food led to increased research and development of biopesticides as crop protection options in modern agriculture. This paper brings into perspective the global history of the application and use of botanical biopesticides in crop production. It also highlights the research progress, product development and registration challenges, and opportunities for business and adoption at the farm level in Kenya.