Alterations Induced by Cowpea Weevil Callosobruhus maculatus F. (Coleoptera: Chrysomelidae) Infestation on Seed Germination Potential and Nutrient Quality of Vigna aconitifolia (Jacq.)

Aims: To evaluate alterations induced by cowpea weevil Callosobruhus maculatus (C. maculatus) infestation on seed germination potential and nutrient quality of Vigna aconitifolia (V. aconitifolia).

Experimental Design: The research was carried out in a complete randomized block design.

Place and Duration of Study: Department of Botany, University of Calabar, Calabar, Nigeria, between March and June, 2016.

Methodology: A mix of V. aconitifolia seeds was bought, infested seeds sorted from the non infested ones at different levels of infestation and kept for three months before planting to ascertain alteration induced by C. maculatus on seed germination potential. The other seeds were sundried, milled into powder and used for proximate, minerals and vitamins analysis.

Results: Significant (P = .05) alterations induced by C. maculatus on seeds germination ability and nutrient quality of V. aconitifolia were observed. These changes varied according to the severity of infestation. The germination potential of seeds was affected with significant reductions observed at all levels of infestation with respect to soil types compared to seeds before infestation (BI). Seed germination was the highest in sandy and loamy than in clay soil. Percentage germination observed on the eleventh day for seeds planted on clay, sandy and loamy soil were 61.7%, 87.1% and 66.7% (BI) compared to values of 4.2%, 6.1% and 5.3% respectively at severe infestation (SI). Results revealed that after infestation (AI) seeds of V. aconitifolia had significant (P = .05) decrease at SI level of 10.1% for moisture, 44.2% (ash), 25.5 % (fat), 18.0% (fibre) and 12.4% (carbohydrate) while protein had increase of 40.2%. P, Na, Cu and Ni showed decrease in content while K, Ca, Mg, Fe, Zn, Mn, Co depicted increase at all levels of infestation compared to seeds content BI. Lead was not detected. Significant decrease in vitamins A, BI, B2, B3, B5, B6, B9, C and biotin contents of the cowpea with decrease in severity of infestation was found. Vitamin E revealed increase with increase in severity of infestation.

Conclusion: Callosobruchus maculatus infestation damaged seeds resulting in a reduction in the germination ability and marketability of V. aconitifolia seeds with severe alteration in nutritional quality.