Host Preference Dynamics of Rice Weevil (Sitophilus oryzae L.) in Stored Cereals

Abstract Exploring the host preference dynamics of rice weevil ( Sitophilus oryzae L. ) can establish effective pest management strategies in stored cereals. Despite the importance of stored product pests in agriculture, limited studies have focused on the grain preference of rice weevil in different cereal grains under controlled conditions. This study aimed to evaluate the host preference of S. oryzae in six different cereals and assess their resistance to infestation. The experiment was conducted at the Entomology laboratory of Rampur Campus, Chitwan, from May to August 2025 under both free-choice and no-choice conditions. Six treatments comprising one hundred grains each of rice, maize, wheat, barley, sorghum, and oats were evaluated in a Completely Randomized Design (CRD) with four replications. Fifteen pairs of newly emerged rice weevils from the stock culture were introduced under no-choice conditions, whereas fifty pairs per replication were introduced under free-choice conditions. The assessed parameters were grain damage percentage, weight loss percentage, and germination percentage before and after the treatment. Under free-choice conditions, wheat recorded the highest grain damage (28.25%) and weight loss (20.01%), whereas oats showed the lowest damage (3.25%) and weight loss (1.52%); the greatest reduction in germination was also in wheat (20%) and the smallest in oats (3%). Under no-choice conditions, wheat again had the highest grain damage (14.50%) and weight loss (17.44%), both significantly greater at the 0.1% level, while oats had the lowest damage (4.75%) and weight loss (2.21%); correspondingly, the highest reduction in germination occurred in wheat (18%) and the lowest in oats (3%). This study establishes that wheat is a highly preferred host, while oats exhibit higher resistance against rice weevil.