Management of the Mexican Bean Weevil by Adding Aromatic Plant Derivatives in Two Dry Formulations

Abstract

<p><strong>Background.</strong><em> Zabrotes subfasciatus</em> (Boh., 1833) (Coleoptera: Chrysomelidae: Bruchinae), is considered one of the most important pest of stored beans. <strong>Objective. </strong>This study reports the possible toxicity and repellence of powders prepared from eight plant species against the Mexican bean weevil in two formulations (dry powder and sachets). <strong>Methodology.</strong> A 10 <sub>˟</sub> 2 factorial design (10 species <sub>˟</sub> 2 formulations) with 8 repetitions in a completely randomized design was employed. Pots with no powder were used as a negative control, and a pyrethroid insecticide [K-Obiol<sup>®</sup> 2 DP (deltamethrin, 0.5 g a.i. ton<sup>-1</sup>)] was applied as a positive control. <strong>Results.</strong> A mixture of powdered <em>Chenopodium ambrosioides </em>L., <em>Ruta graveolens </em>L. and <em>Mentha pulegium</em> L. added to bean grains was confirmed to be toxic to <em>Z. subfasciatus</em> adults with promising grain protector properties. <em>C. ambrosioides </em>powder had the same effect when in a sachet. A mixture of powdered <em>R. graveolens</em>, <em>M. pulegium </em>and <em>C. ambrosioides </em>with the beans inhibited weevil oviposition. The same effect was achieved for <em>M. pulegium </em>and <em>C. ambrosioides </em>in sachets. A mixture of powdered <em>C. ambrosioides</em>, <em>M. pulegium</em>, <em>R. officinalis</em> and <em>R. graveolens </em>repelled <em>Z. subfasciatus</em> adults from bean grains. <strong>Implications.</strong> This is the first report of using botanical derivatives by means of sachets or dry formulations, a pre-commercial purpose for aromatic plants with insecticidal/repellent activities. <strong>Conclusions.</strong> Sachets containing powdered <em>C. ambrosioides </em>and <em>M. pulegium </em>efficiently controlled the Mexican bean weevil in stored beans and constitute an useful tools for domestic grain stock or post-harvest management of organic grains.</p>