Effect of sorghum cultivars on population growth and grain damages by the rice weevil, Sitophilus oryzae L. (Coleoptera: Curculionidae)

In northern Cameroon, the rice weevil, Sitophilus oryzae L. (Coleoptera: Curculionidae) is a major pest of Sorghum bicolor (Poaceae) during storage. This staple crop is currently damaged by many insects and others pests during storage. To reduce the post-harvest losses due to S. oryzae, many control strategies are performed. An important step to achieve successful control is to isolate and characterize the noxious activity of rice weevil present on the sorghum variety currently stored. The present study shows that the two main ecotypes of S. bicolor, the "djiigari" ecotype is very susceptible to the 7 weevils strains isolated in the region. In a period of 100 days a single female of one of the most prolific strains produces 24 adults and more than 57% of grains are attacked. In the "safraari" ecotype, the level of attack is very low. This suggests that efforts should be made to advice the farmers to prefer "safraari" ecotype in order to avoid post harvest losses due to S. oryzae.