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. 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. Moreover, correlation analysis revealed significant nega
tive correlations between seed hardness and the development time of S. oryzae, indicating that harder seeds tend to prolong the development period of the weevils. Conversely, there were significant positive correlations between protein content and fecundity, suggesting that higher protein content in the grains supports greater reproductive output in S. oryzae. Starch content and humidity content also played crucial roles, with higher starch content being associated with increased intrinsic rates of increase (r) and higher humidity content correlating with shorter development times.
These findings highlight the importance of grain physicochemical properties in influencing the biological performance and population dynamics of S. oryzae. The results suggest that managing these properties through selective breeding or post-harvest treatments could be a viable strategy to mitigate the impact of rice weevils on stored cereal grains. For instance, developing grain varieties with increased hardness or lower protein content could potentially reduce the reproductive success and population growth of S. oryzae, thereby minimizing the damage caused by this pest.
In conclusion, the study underscores the complex interactions between grain species and the life history traits of S. oryzae, providing valuable insights for developing integrated pest management strategies. Future research could further explore the genetic basis of these physicochemical properties and their manipulation to enhance resistance against rice weevils and other similar pests.