Abstract
Common beans (Phaseolus vulgaris) remain an important dietary protein source in Malawi. However, its production is highly hindered by insect pest and disease attack. The study aimed at evaluating the effectiveness of Tephrosia vogelii and Tephrosia candida extracts against bean aphid (Aphis fabae). The evaluation involved two botanical extracts at three different concentrations (0.5%, 2%, and 5% w/v) against bean aphid. Plant extracts (leaves) were air-dried and milled. Powders were then soaked in a 2-litre plastic bucket of cold water. Results indicated that there was significant difference (P<0.05) among treatments. The effectiveness of the treatments was based on reduction in aphid population per plant, pod length, and bean yield. Pod length and bean yield were higher in T. vogelii and Karate as compared to untreated and T. candida. There was a high mortality rate of aphid on the plots treated with T. vogelii compared to plots treated with T. candida at the same concentration. Though these two plant extracts were not as effective as the synthetic insecticide in reducing aphid population, they were considerably and significantly found to be effective; hence, its use by poor-resource farmers is recommended in the protection of bean against aphid.
Highlights
Crop production is hindered by multiple factors that are impacting global food and nutrition security (Michalik et al, 2006; Nderitu et al, 2010; [1])
The study has demonstrated the possibility of using extracts from T. vogelii and T. candida on bean aphids since farm products for protection is believed to reduce infestation levels of various pests below economic threshold level and can substantially increase yield
The present study has demonstrated that T. vogelii at 5% w/v concentration reduced common bean aphid which led to higher yields than T. candida
Summary
Crop production is hindered by multiple factors that are impacting global food and nutrition security (Michalik et al, 2006; Nderitu et al, 2010; [1]). It is anticipated that by 2050, pressure on food and nutrition requirements is likely to increase due to projected population increase (Stevenson and Belmain, 2017). This entails that production of crops as food and nutrition source is paramount. Despite year round availability of beans to maintain food and local market demand, its production systems are so challenging ([2]; Nderitu et al, 2010). This crop is produced by smallholder growers whose farm size is ranging from 0.25 to one hectare; climatic variability and pest and disease attack remain some of the critical challenges. The damage on leaves leads to retarded growth, while on blossoms it makes the flowers prematurely abort, causing low yield (Nderitu et al, 2010)
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