Establishment and spread of Cotesia flavipes Cameron: Implication on the local population of Chilo partellus (Swinhoe) across three agroecological zones in Kenya

Chilo partellus causes yield losses estimated at 73-100% in maize and 88-100% in sorghum in Kenya. icipe spearheaded the importation and release of the larval parasitoid, Cotesia flavipes, in moist lowland, dry mid-altitude and moist mid-altitude Agro-Ecological Zones (AEZs) of Kenya against C. partellus. However, the establishment of C. flavipes is only well documented for the moist lowland AEZ. This study was thus carried out in the three AEZs in order to update establishment, spread and impact of the parasitoid on stem borer populations. Maize and sorghum farms were sampled radiating from parasitoid release points up to a distance of 45 km. Percentage infestation and parasitism were analyzed using one factor ANOVA or Kruskal-Wallis test. Results of this study revealed that C. flavipes established and spread beyond release sites across the three AEZs. Overall stem borer infestation was 28.9 ± 3.1, 22.5 ± 7.4 and 2.7 ± 0.4% in the moist lowland, dry mid-altitude and moist mid-altitude AEZ, respectively, showing a significant reduction from parasitoid pre-release levels. Stem borer parasitism levels were 36.1 ± 3.0, 25.3 ± 3.3 and 5.5 ± 2.5% in the moist lowland, dry midaltitude and moist mid-altitude AEZ, respectively, showing a significant increase from parasitoid pre-release levels. Cotesia flavipes is steadily suppressing stem borer population in the three AEZs.