Influence of Agro Ecology on Rice Varietal Resistance to Sitophilus oryzae (Coleoptera: Curculionidae) and Sitotroga cerealella (Lepidoptera: Gelechiidae) in Benin.

Abstract

The rice weevil, Sitophilus oryzae (L.) and the Angoumois grain moth, Sitotroga cerealella (Oliv.), are serious pests of stored rice in Africa. This study aims to evaluate the influence of growing environments to rice resistance to these pests. Thus, eleven rice varieties including 6 upland NERICA, 2 Oryza glaberrima and 3 O. sativa were grown at four agro ecological zones of Benin. After harvest, samples of 1500 grains of each genotype were infested with 20 adults of S. oryzae (10 males and 10 females) and 1500 additional ones were infested with 50 eggs of S. cerealella. Results showed significant effect of agro ecological zones on pest incidence and on varietal resistance as well. O. glaberrima varieties (TOG 5681 and CG 14) were the most resistant in each location whereas the resistance of NERICA and Sativa varieties varied from tolerant to susceptible according to the growing ecology. This result highlights the impact of growing environment on rice resistance status and will provide the best advice to farmers on how to choose best genetic material according to cropping ecology.