Abstract

Faba bean, Vicia faba L. is an important legume crop that substitute animal proteins especially in developing countries. Bean bruchids or bean weevil, Accanthoscelides obtectus Say is a major insect pest of the faba bean grains mainly in the store. An experiment was conducted in Debremarkose University to screen effective botanical oils for the management of bean bruchids on faba bean grains. The tested oils were from seeds of Noug (Guizotia abyssinica L. f.), Rapeseed (Brassica napus L.), Lantana (Lantana camara L.), Pepper (Capsicum annum L.), Tephrosia (Tephrosia vogelii Hook), Groundnut (Arachis hypogaea L.) and Castor (Ricinus communis L.). The untreated check, Acetone (solvent used to extract oils from the botanicals) and Ethiothion 5% dust (a standard check) were used for comparison. One day after treatment application, the dead bruchid in Ethiothion 5% dust, noug oil and rapeseed oil treated grains were 100, 90.85±0.63 and 78.35±0.78%, respectively indicating the fast knock down effect of the treatments. Four days after treatment, 100% of the parent bruchids were killed in all oil treated grains. The mortality of the parent bruchids four days after treatment application was 10.85+0.6% in acetone treated grains and 11.65±0.5% in untreated grains. Statistically lower number of eggs and progeny (adults) were recorded from Ethiothion 5% dust and oil treated grains than the acetone treated and untreated grains. Bean grain losses due to bruchids were 18.3±0.4% in acetone treated grains and 18.4±0.44% in the untreated check, while 0 to 5.2±0.27% losses were recorded in other treatments. Ethiothion 5% dust and the oils inhibited emergence of bruchids from 71.7±2.56 to 100±0.53%. Lower germination percentages were recorded from acetone (67.3±4.23%) treated grains and the untreated grains (66.7±3.02%). From the results of this experiment, it can be concluded that the Ethiothion 5% dust and all the tested oils can effectively control bean bruchid and recommended for the management of the same.    

Key words: Bean bruchid/weevil, botanical oil, faba bean grain (Vicia faba L.), mortality, survival, progeny.