Assessing the bio-efficacy of Pine (Pinus sylvestris L) essential oil against bean aphids ( Aphis fabae)

Abstract

Black bean aphids remain a major crop pest especially to beans; this is because they carry various diseases as well as bringing about nutrient depletion through their sucking activity. Synthetic pesticides have been widely used as an effective solution to these pests. However, synthetic pesticides are associated with negative side effects on biodiversity and human health. This study was conducted to determine the bio-efficacy of Pine oil against black bean aphids as a way of mitigating the negative effects associated with synthetic pesticides. Pine oil extracted by hydro distillation was dissolved in distilled water to for concentrations of 100, 60, 40, and 20ml/L. These were sprayed directly on apterous aphids maintained on live bean of the Nambale Variety; distilled water and dudu-acelamectin 5% EC acted as the negative and positive control, respectively. Applications were made at 12 hours interval for three days. A significant reduction in number of apterous aphids was observed on plants treated with 100ml/L. Lethal concentrations required to cause 50% and 90% mortality were 61.27858 and 169.0765 ml/L respectively. Therefore, Pine oil presents a potential substitute for the rather harmful synthetic pesticides.