Pesticides Residues in Stored Cowpea (Vigna unguiculata L.Walp) Grains in Three Markets in Maiduguri, North-Eastern Nigeria

1Goniri A. L., 1Hauwa T., A*., 1Umar. A. and 2Babamai, S.

1Department of Zoology, University of Maiduguri Borno State Nigeria
2Departments of Veterinary Physiology and Biochemistry, University of Maiduguri, Borno State, Nigeria

*Corresponding author’s Email: tati66.ng@gmail.com, doi.org/10.55639/607.02010031


ABSTRACT

Cowpea (Vigna unguiculata L. Walp) is a vital staple crop in Nigeria, serving as a key protein source and economic commodity. However, postharvest losses caused by insect pests, particularly Callosobruchus maculatus, have led to widespread pesticide application for storage protection. This study assessed pesticide residues in stored cowpea grains from three major markets in Maiduguri: Muna Garage, Baga Road, and Monday Market. Thirty cowpea samples were randomly collected and analyzed for organochlorine, organophosphate, pyrethroid, and carbamate residues using High-Performance Liquid Chromatography (HPLC). Results indicated the absence of organochlorine and carbamate residues, but pyrethroid (cypermethrin) and organophosphate (DDVP) residues were detected. Cypermethrin residues were found in all study sites, with concentrations ranging from 0.003–0.017 mg/kg, while DDVP residues ranged from 0.003–0.035 mg/kg, with higher concentrations observed at the bottom layers of storage sacks. Some values exceeded the WHO Maximum Residue Limits (MRLs), raising food safety concerns. The findings highlight the need for stricter pesticide regulation, increased awareness among grain traders, and improved cowpea storage management to mitigate health risks associated with pesticide residues.

Keywords:

Cowpea,
Pesticide residues,
HPLC,
Organophosphates,
Pyrethroids