EFFICACY OF SELECTED BIOPESTICIDES AND HOST PLANT RESISTANCE IN MANAGEMENT OF POD BORER (Helicoverpa armigera Hubner) AMONG PIGEON PEAS (Cajanus cajan Millsp.) IN SEMI-ARID AREAS OF KENYA

Abstract

Pigeon pea (Cajanus cajan (L.) Millsp) production in Kenya is primarily low and unsteady due to vulnerability to numerous strains mainly, pod borer (Helicoverpa armigera Hubner) in dryland production systems. Insecticide sprays have been used in the past to control the pest, however, they are dangerous and toxic to humans, animals and beneficial organisms. Therefore, alternative integrated pest management control measures are required to reduce yield losses and enhance productivity and food security. The objectives of this study were to determine (i) morpho-physiological pest-adaptive traits contributing to pod borer host plant resistance under field conditions and (ii) the effect of selected biopesticides on pod borer management and grain yield performance of selected pigeon pea genotypes under field conditions. There were two experiments conducted for two seasons at Kerio Valley Research Station in Elgeyo Marakwet County and at Agricultural Training Centre (ATC) in Baringo County. Eight genotypes were evaluated for resistance against pod borer under field conditions in a Randomized Complete Block Design. Three biopesticides (Nimbedicine®, Pyagro® and Bacillus thuringiensis®) were evaluated for their efficacy and yield performance and were laid out in Split Plot Design. Positive and negative controls included application of one commercial pesticide and unsprayed treatment respectively. All trials were replicated three times. Data was collected on morpho-physiological parameters (trichomes and pod wall thickness), yield and yield components, severity and incidence of pod borer infestation. Data was subjected to analysis of variance (ANOVA) using SAS version 9.2 Statistical Software at 95 % confidence. Tukeys Honest Significance (HSD) test was used to separate means whenever effects are significant at (P≤0.05). Results showed EUMDP 4, Ndombolo, Kendi and ICEAP 00068 as promising tolerant genotypes while Nimbedicine® and Pyagro® as the best biopesticides for pod borer control. The findings of this study have helped in identifying the most appropriate biopesticide for control of pea pod borer in ASALs of Kenya and its use in integrating host plant resistance for better management of pigeon pea pod borer and enhance productivity. Information on morpho-physiological traits influencing host plant resistance is essential in improving selection index in pigeon pea breeding programs.