Morphotypic characterisation of Sitophilus zeamais (Coleoptera Curculionidae) in southwest Nigeria
Three food host of S. zeamais : maize, red sorghum and white sorghum were obtained from three purposively selected locations in each of Oyo, Ogun ,Ondo, Osun and Kwara States of Nigeria. The food hosts were evaluated for occurrence of S. zeamais in the Entomological Research Laboratory of the Department of Crop Protection and Environmental Biology, University of Ibadan, using completely randomized design. At F1 emergence, adult male and female were measured for the following characters: rostrum length, length of elytra, number of suture line on elytra and body length, in the laboratory, the measurement taken were done in ten replicates. Data were analyzed using descriptive statistics and ANOVA.
Comparatively, the morphological variation in characters of body length (3.8-4.35mm), rostrum length of male (0.7-0.85mm), and female (1.01-1.11mm), elytra length of male (1.78-1.89mm), and female (1.71-1.89mm) differed significantly (p<0.05) with food hosts, being longest in emergents from maize (1.78-1.89mm) followed by red sorghum (1.61-1.79mm) and white sorghum (1.65-1.76mm). The average number of suture line recorded was 11 in both male and female irrespective of the food host. Based on the length on the characters studied, four populations of S. zeamais were identified as existing in southwest Nigeria.
