Efficacy of Food Bait Attractants in Reducing Sitophilus oryzae Populations in Stored Paddy

The rice weevil (Sitophilus oryzae L.), a major pest of stored grains, relies heavily on olfactory cues for host selection and localization. This study evaluated the behavioral responses and attraction efficiency of S. oryzae to various food-based baits under laboratory conditions using olfactometer bioassays, trap-based assessments and bait ratio trials. Bait traps filled with different food attractants wheat flour, sorghum flour, pearl millet flour and combinations thereof were deployed in a simulated storage environment. Observations over 25 days revealed that wheat flour was the most attractive bait, achieving a total attraction rate of 64.70%, followed by sorghum flour (58.71%). Combination bait trials demonstrated that a 2:1:1 ratio (wheat flour: sorghum flour: pearl millet flour) yielded the highest insect recapture (181 out of 700 released), indicating optimal arresting efficacy. Four-arm olfactometer assays further confirmed the strong olfactory-driven orientation of S. oryzae towards wheat and sorghum volatiles. Behavioral observations showed a peak in insect settling at 25 minutes after release (MAR) and highest retention on wheat-based substrates. The results suggest that wheat and sorghum flours can serve as highly effective attractants for the monitoring and management of S. oryzae in stored grain systems. This study provides a foundation for the development of sustainable, bait-based pest control strategies in post-harvest storage environments.