The leaves of Solanecio manii were collected from sampled plants in Kandara Sub-County Muranga County in Kenya. The aim of collection of the leaves was to carry out the extraction and analysis of essential oils from S. manii. The leaves were transported to the pharmacognosy laboratory at the Mount Kenya University. The leaves were washed with running tap water and rinsed with distilled water to remove physical and chemical contaminants. They were air dried on the laboratory benches for seven days to lose 90% of moisture content. The essential oils (Eos) were extracted from 200.000 g of dry leaves by hydrodistillation using the Clavenger apparatus for 8 hours. The rate of essential oil production from the leaves was computed and found to be 0.01%. GC-MS instrument was utilized to analyse the qualitative and quantitative composition of essential oils. The compounds that were found present in the total ion chromatogram were, 3-Carene (40%), Limonene (35.48%), 1-undecanol (8.0%), β-pinene (6.4%), Menthol (1.6%), β-Cymene (1.1%) Longifolene (0.78%) and α-terpenolene (0.5%).

Natural sources of biopesticides such as plants and microorganisms are widely employed for pest management globally. Over the last five decades, the use of biopesticides has been explored as a safer alternative to synthetic pesticides. This study determined the repellence and contact toxicity of essential oils from Ocimum kenyense plant against Thrips tabaci, Bemisia tabaci, and Aphis gosypii. The essential oils (Eos) were extracted from dry leaves by hydrodistillation using the Clevenger apparatus for 8 hours. The composition of essential oils was qualitatively and quantitatively analysed using GC-MS, while ATR-FTIR was used to determine the functional groups. The major compound ion in the Eos was 1,8-Cionele while the major phytochemical identified was Eucalyptol Bioassay of the crude extracts were carried out on T. tabaci, B. tabaci, and A. gosypii. Contact toxicity and repellency tests against mixed-sex adult pests were carried out on T. tabaci, B. tabaci, and A. gosypii. In contact toxicity, five different concentrations were prepared and each was replicated five times. Acetone was used as a negative control, while permethrin, a commercial chemical pesticide was used as a positive control. The LD50 of the essential oils was determined by Probit analysis SPSS version 26.0. The response to the treatments was observed after 24 hours by using a blunt object probing and the pests that did not respond were counted as dead. It was found that essential oils from O. kenyense had the lowest LD50 of 0.127 µL against A. gosypii. This implies that O. kenyense can be used as a contact toxicant against A. gosypii. Repellency tests were carried out at four different concentrations. N, N-Diethyltoluamide (DEET) repellent from a commercial mosquito repellent was used to compare the effectiveness of the essential oils against commercial repellents. The repellency test responses were observed after 1 hour and the data was used to determine the correlation between different levels of concentration of Eos and percentage repellency of Eos of O. kenyense leaves carried out at α=0.05. There was a high correlation of 1.000 between the increase in concentration of Eos and repellency against A. gosypii, T. tabaci and B. tabaci. The results were statistically significant and (P<0.05, α=0.05). Therefore, essential oils from O. kenyense can be used as a contact toxicant biopesticide against A. gosypii and a repellent biopesticide against A. gosypii, T. tabaci and B. tabaci.

ATR-FTIR analysis is a robust method that is used to analyse solids and liquid samples with minimal sample preparation. The samples are usually placed on the ATR crystals and pressure applied to obtain a clear spectrum. Essential oils from O. kenyense were extracted through hydro distillation using the Clavenger apparatus for 8 hours. The essential oils were dried by passing through anhydrous sodium sulphate after which they were placed in brown viols and refrigerated at 4℃. The sample of oils was latter analysed at the government chemist in Nairobi County in Kenya. Compounds that recorded a high hit quality of 600 and above had the highest probability of being present in the oil. Eucalyptus oil had a hit quality of 673 and 1, 8-cionele had a hit quality of 655 respectively. Therefore, the two were presumed to be present in O. kenyense essential oils

Plants and microbes provide naturally occurring chemicals that are often used for the control of pests all around the world. Biopesticides have been used as a comparatively safer replacement for synthetic pesticides for the past five decades. This study determined the contact toxicity of essential oils from the Tithonia diversifolia plant against Thrips tabaci, Bemisia tabaci, and Aphis gosypii. The essential oils (Eos) were extracted from dry leaves by hydrodistillation using the Clavenger apparatus for 8 hours. GC-MS was utilised to analyse the qualitative and quantitative composition of essential oils, whereas ATR-FTIR was employed to determine the functional groups. 3-Carene was the most abundant compound ion in the Eos. T. tabaci, B. tabaci, and A. gosypii were used in the bioassay of the crude extracts. T. tabaci, B. tabaci, and A. gosypii were tested for contact toxicity against mixed-sex adult pests. Five distinct concentrations were made, each of which was repeated five times. Permethrin, a commercial chemical pesticide was utilised as a positive control and acetone were used as a negative control. The essential oils’ LD50 was calculated using SPSS version 26.0 Probit analysis. After 24 hours, the pests’ response to the treatments was assessed using a blunt instrument probe, and those that did not respond were counted as dead. Essential oils from T. diversifolia had the lowest LD50 against T. tabaci, with a value of 0.085 µL. This suggests that T. diversifolia could be employed as a T. tabaci contact toxicant. (P < 0.05, α = 0.05) The outcomes were statistically significant. As a result, essential oils from T. diversifolia can be employed as a biopesticide against T. tabaci as a contact toxicant.