Varietal resistance of soybean to Callosobruchus maculatus and protection of the soybean seeds using Gnidia kraussiana root extracts

Abstract

Soybean (Glycine max L.) is a key source of plant protein and oil in sub-Saharan Africa, but its storage is affected by the cowpea seed beetle, Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae). The present study investigated the C. maculatus resistance of 10 soybean varieties in 2 agroecological zones of northern Cameroon and evaluated the protective efficacy of Gnidia kraussiana root extracts compared to neem seed oil on a susceptible variety. Significant varietal differences in C. maculatus susceptibility were observed, with resistance varying across locations. Only a subset of varieties (e.g., TGx1844-18E, SJ235, VT/SG Houla1, and Emgopa314) exhibited consistent resistance across both sites, and others showed location-dependent responses. Kodek/Houla1 displayed variable susceptibility and was classified as moderately susceptible in Maroua and moderately resistant in Ngaoundéré. Resistance was associated with seed biochemical traits. The soluble sugar content was positively correlated with suscepti