Comparative Morphometry of the Sitophilus zeamais Motschulsky Populations (Coleoptera: Curculionidae) Infesting Yellow Maize in Four West African Countries

Sitophilus zeamais is a primary pest of stored maize, which can cause quality and quantity losses. Maize is cultivated in several West African countries where different agro-climatic and agro-ecological conditions exist. These conditions could influence the Sitophilus zeamais morphology. Thus, the purpose of this study is to identify the Sitophilus zeamais morphological groups in the four countries. This was carried out through the morphometric study of 30 male Sitophilus zeamais individuals taken from the yellow maize in each country, by measuring with a binocular magnifying glass, 16 variables of the different tagmas belonging to the insect. Subsequently, statistical analyses were firstly carried out with the raw measurements, such as the principal component analysis, in order to extract the contribution of the variables on each factorial axis and to visualise the correlations between the variables. Taking the case of the transformed measurements, in addition to the principal component analysis, a discriminant factorial analysis was carried out to find out the best factor for gathering individuals according to their morphology, a confusion matrix to summarise the individual’s reclassification in order to deduce the good and bad classification rates, and an ascending hierarchical classification which consists of gathering the individuals according to their similarity and separating them according to their dissimilarity using the truncation method. Therefore, five morphological groups were identified. However, the existence of these morphological groups would not be linked to