Physical and biochemical characteristics of cereal grains affect population growth parameters of Sitophilus oryzae (L.) (Coleoptera: Curculionidae)

The rice weevil, Sitophilus oryzae L. (Coleoptera: Curculionidae), is a significant pest of rice and other cereal grains. In this research, the effects of various grain species, including barley, maize, millet, rice, sorghum, and wheat, were assessed on biological properties and life history variables of S. oryzae under laboratory conditions. Data were analyzed based on the age-stage, two-sex life table method. Furthermore, various physicochemical properties of cereal grains, including protein content, starch content, humidity content, and seed hardness, were investigated to explore their correlation with the studied parameters of S. oryzae. The longest development time was observed on millet and sorghum hosts, while the shortest was on maize seed. The beetles reared on rice and millet species showed the maximum fecundity, whereas those reared on sorghum and millet grains showed the lowest. Maize grain had the highest intrinsic rate of increase (r), whereas millet and sorghum grains had the lowest. According to the correlation analysis, overall, seed protein content was negatively correlated with insect fecundity, R₀ and r, but positively correlated with development time. Furthermore, starch content was positively correlated with insect fecundity, R₀ and r, and negatively correlated with development time. The cluster results demonstrated that whereas sorghum and millet were comparatively resistant hosts for the growth of S. oryzae, maize and rice were relatively susceptible seeds. This information can be helpful in the development or improvement of integrated pest management (IPM) strategies against rice weevil. The findings of this research will also be helpful in introducing unsuitable hosts for the development of transgenic grains resistant to S. oryzae. The pest-resistant cereal grains identified in this study can potentially be utilized in combination with other pest control strategies for sustainable management of S. oryzae, which may help reduce the excessive use of chemical insecticides.