EFFICACY OF LEAF EXTRACTS OF ARTEMISIA ANNUA AND THEVETIA PERUVIANA AGAINST APHIS FABAE AND NON-TARGET ORGANISMS ON SOLANUM SCABRUM IN KENYA

Abstract

African nightshade (Solanum scabrum Miller.) is a Solanaceae vegetable, widely distributed throughout the tropics including East Africa. It is an important vegetable in Kenya but consumer demands have not been met due to low yield per unit area planted and partly due to attack by Aphis fabae Scopoli. The aphids causes serious direct feeding damage by sucking plant sap leaving the plant weakened, stunted in growth and eventually under heavy infestation the leaves curl making the vegetables unattractive to customers. Synthetic insecticides have been used to control aphids but they have developed resistance, are risk to human health and they kill important non-target organisms e.g. predators, parasites, pollinators, soil micro organisms like bacteria and fungi and living organisms in water bodies. This study will assess the efficacy of leaf extracts of Artemisia annua Linn. and Thevetia peruviana (Pers.) Schumann. in the control of A. fabae infesting S. scabrum. The effects of plant extract on non-target organisms and yield will be determined. Field experiments will be carried out in Masinde Muliro University of Science and Technology’s Main Campus farm. A randomized complete block design of six treatments and three replicates will be used. The treatments will be A. annua 0.5%, A. annua 1%, T. peruviana 0.15%, T. peruviana 0.3%, Albaz 10 EC insecticide and water. The species of the African nightshades that will be used is S. scabrum whose seeds will be purchased from Kenya Seed Company, A. annua and T. peruviana leaves will be obtained from Masinde Muliro University of Science and Technology Botanical Farm in Kakamega. The extracts will be prepared using maceration method using methanol as a solvent. Parameters to be collected in the field experiments will be determining A. fabae population, scoring the aphid damage, assessing the diversity of non-target organisms, plant height, leaf width, leaf yield by taking the fresh and dry weight of leaves of all the plants per treatment and fresh and dry weight of seeds. Laboratory work will include preparation of extracts, identifying non-target organisms and evaluating the impact of leaf extract on non-target organisms and weighing of yields. Data will be analyzed using ANOVA, correlation and regression. Statistical tests used will be F-test and Chi-test. Summary statistics will be mean and standard error. The significance of this study is that the findings will determine the potential of leaf extracts of T. peruviana and A. annua in control of A. fabae infesting S. scabrum.