Présence, populations et dégâts de l’alucite des céréales Sitotroga cerealella (Olivier) (Lepidoptera,Gelechiidae) sur les stocks de riz au Bénin

Abstract

The Angoumois grain moth, Sitotroga cerealella (Olivier) (Lepidoptera, Gelechiidae), is a major pest on several continents causing major damage to stocks of several cereals (rice, maize, sorghum etc.). This study aimed at analyzing the presence of S. cerealella in key sites of rice production in Benin and evaluating the level of the pest population and its damage to farmers’ rice stocks. For this purpose, paddy rice samples were collected from 11 sites of peasant stockage. In addition, pheromone traps were placed in farmers’ paddy fields to study infestations. The results showed that 70 % of the rice stocks were infested by S. cerealella, with average populations varying from 30 to 300 individuals per kg of paddy. In infested samples, the damage level ranged from 3% to 18 % of grains attacked for 2 to 4 months of storage. Pheromone trapping showed that 80 % of the rice fields were infested, with an average of 16 individuals captured per trap. The presence of this pest is thus confirmed on rice in Benin. This study also shows that important damage can be caused on stored rice as soon as the storage period reaches 3 to 4 months.