Groundnut field infestation in different pedoclimatic sites by the peanut beetle, <i>Caryedon serratus</i> (Olivier) and conducted losses

Abstract

Groundnut (Arachis hypogea L.), used for direct consumption and cooking oil in several African countries, suffers tremendous losses  during storage due to pests. The main pest of groundnut under prolonged storage in tropical countries is the peanut beetle, Caryedon  serratus (Olivier) (Coleoptera; Bruchidae). The present study aimed at (1) assessing the variability of field pods infestation by C. serratus  on sites of different pedoclimatic conditions and at (2) evaluating the losses in laboratory storage. Groundnut pod samples were collected  in six sites of Senegalese groundnut main farming areas (Bambey, Sandiara, Kaffrine, Coki, Keur Baka and Keur Ayib), and  placed in glass jars (5 L) aerate with lid mesh (2 mm) and brought to laboratory. Number of eggs, insect progeny, emerged insects’  weight, survival rate, percentage of attacked kernels and weight loss were assessed and confronted among different sampling sites (field  soil pH and moisture content, and photoperiodicity). The results showed a presence of groundnut bruchid in all sites, with significant  variations of eggs on pods during the drying period across the sites. These variations in field infestation can be explained by several  factors such as cultural practices and field environmental factors which varied greatly between the sites. Considering these factors and  our preliminary results, this study suggests to dry the groundnuts furthest possible from the beetle hosts trees (wild hosts  Cesalpinaceae) and shorten the pod exposure time in field as much as possible, in order to control this preharvest infestation and reduce  groundnut storage losses.