Abstract

Common bean Phaseolus vulgaris is highly attacked during storage by Acanthoscelides obtectus which reduces seeds quantity, quality and germination rate. Due to the hazards of synthetic chemicals to humans and the environment, there is a need to promote the application of phytochemicals. Orange peel powder, cypress leaf ash and their mixture were assessed against A. obtectus and to determine their influence on seed germination. Four concentrations (5, 10, 20 and 30 g/kg) of the botanicals were applied. Analysis of essential oil extracted from Citrus sinensis revealed limonene as the main volatile (90.77%). Orange peel powder was less effective against A. obtectus with 12.5 % mortality at the content of 30 g/kg within 5 days post exposure. Cypress ash and its combination with orange peel powder recorded 98% and 86% mortality respectively within the same period. The tested formulations were effective in inhibiting F1 progeny thereby leading to less grain damage and weight loss. In addition, there was no significant effect of botanicals on stored seeds about the germination rate. Both plant products could be a major component for the protection of beans against A. obtectus attacks because it is easy to wash the treated seeds to remove residue of botanicals.

Key words: Botanicals, bioactivity, Acanthoscelides obtectus, common beans, germination.