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Parasitoids are the most important bio-control agents in suppressing C. partellus populations. The exotic larval parasitoid, Cotesia flavipes Cameron was introduced into East Africa as a classical bio-control programme of cereal stem borers' mainly Chilo partellus. In Ethiopia this parasitoid has never been released but it was found established and has been reported attacking C. partellus on sorghum. The abundance and impacts of C. flavipes on the population reduction of C. partellus were studied at different phenological stages of sorghum in three districts of South Wollo zone, Ethiopia, during 2016/17 and 2017/18. Result showed that C. flavipes' abundance revealed significant difference among sorghum growth stages and across the districts. C. flavipes recorded abundantly at maturity stages of sorghum. The highest number (0.48) was recorded from Bati with the relative abundance of 33.8%. Parasitism by C. flavipes varied across the locations and host growth stages. The highest (61.5%) parasitism percentage was recorded from Bati at maturity in both seasons. In all the study sites parasitized larvae and percent parasitism were positively correlated with the late growth stages and negatively correlated with vegetative stages at Bati and Chefa and was significant at 0.05 levels. In conclusion C. partellus was found attacking by C. flavipes at the late growth stages of sorghum in all districts. Thus it is possible to suggest that the use of this parasitoid can be regarded as a suitable alternative to synthetic insecticides for the management of C. partellus in the field. [ABSTRACT FROM AUTHOR]

The aim of this investigation was to study the effect of physical (ultraviolet light) and chemical mutagen (methyl salicylate) on common bean (Phaseolus vulgaris L.) and how they had positive or negative effect on alpha-amylase activity, phenological plant traits (days to flowering, days to maturity, days of pod fill) and agronomic traits (number of pods per plant; weight of pods per plant; Number of seeds per pod; number of seeds per plant; weight of seeds per plant; plant height; pod harvest index), seed and pod morphological characteristics (seed length; seed width; pod length; pod width). Seeds of common bean were exposed to ultraviolet (UV) light for different periods of exposure time (3 and 5 h) and were soaked with two different methyl salicylate (MeSA) concentrations (0.01 and 0.05 mM). The results indicated that the 5 h exposure to UV light plants were indicated to positively affect alpha-amylase activity, phenological and agronomic traits, seed and pod morphological characteristics as compared to control and other treatments while 0.01 mM MeSA significantly negatively impacted them. Traits of plants exposed to UV light for 5 h were significantly improved. This research could provide a valuable source of materials for common bean breeding. [ABSTRACT FROM AUTHOR]