EFFECT OF Artemisia annua LEAF EXTRACT AND INTERCROPPING ON Aphis fabae, NON-TARGET HONEY BEE AND LADY-BIRD BEETLE IN COMMON BEAN IN NANDI COUNTY, KENYA

Abstract

Common bean produces high yield in Kenya where it is used as human food, livestock feed and a source of green manure. The high incidence of A. fabae is a major threat to common bean farming in Kenya and may result in 42% yield loss. Use of synthetic insecticides to control the pest is associated with several challenges such as high costs, toxicity risks, persistence of their residues in environment and destruction of beneficial organisms. Botanical insecticides have recently received much attention because they are locally available, efficacious, non-toxic, specific and easily biodegradable. Though A. annua has shown efficacy in the control of several pests, very little research has been done on its efficacy in the control of A. fabae despite its availability in Nandi region. Intercropping is a simple and effective measure that offers advantages at reducing pest densities especially where hosts of particular insect pests are intercropped with non-hosts. The objectives of the study are to determine the effect of A. annua leaf extracts on the incidences and severity of A. fabae, on non target honey bees and lady bird beetles and also to evaluate the effect of bean/maize and bean/S. scabrum intercrop systems on the population densities of A. fabae. It is hypothesized that leaf extracts of A. annua will be effective in reducing the incidences and severity of A. fabae on both pure stand and intercropped bean crops while having no negative effect on the non-target and beneficial honey bees and lady-bird beetles. This field study will be carried out in Kaimosi ATC farm, Nandi County between September 2015 and July 2016. The experiment will be laid out in Randomized Block Design with four main treatments and three sub-treatments each replicated thrice. The treatments include; application of A. annua at 5% and 1% concentrations on bean pure stand, bean/maize and bean/S. scabrum intercrops; application of Lambdacyhalothrin insecticide at recommended rate on bean pure stand, bean/maize and bean/S. scabrum intercrops as a positive control; application of distilled water on bean pure stand, bean/maize and bean/S. scabrum intercrops as a negative control. Parameters for data collection will be; number of A. fabae per plant, height of bean plants, width of third fully expanded leaf from the tip, number of crinkled leaves per plant, number of pods per plant, fresh and dry weights of mature plant minus pods, number of shrivelled seeds per plant, dry weight of bean seeds per plant, number of honey bees and predatory lady bird beetles per plant. The data will be analysed by two-way ANOVA using SPSS software. Means will be separated using Tukeys student test at p<0.05. The results of this study will be useful in determining the possibility of applying A. annua and intercropping as a means of controlling A. fabae both at local and regional levels.