Particle Size of Grains and Pulses Affects Infestation by Tribolium Castaneum (Herbst) (Coleoptera: Tenebrionidae)

Abstract

Tribolium castaneumis is a pest of stored rice and other grains. Altered degree of insect infestation in stored food having different particle sizes is reported but such information on local rice varieties and pulses is unavailable. Therefore, we aimed to investigate the relationship between the infestation by T. castaneum varies and the grain type and the percentage of fragments during storage, in selected rice varieties and other grains found in the local market. The experiment used the Completely Randomized Design with four replicates. Five local rice varieties Red Kekulu, Red Samba, Kuruluthuda, Suwandel and Red Heeneti; and other grains cowpea, green gram and black gram were used. From each grain type, samples having brokens as 0%, 10%, 20%, 40%, 60% and 100% were prepared. Twenty T. castaneum adults were introduced into a 20 g replicate sample of each grain type, and removed two weeks following the introduction. Every two weeks following the removal of parent adults, the number of progeny adults emerged in each replicate sample was counted and removed. The progeny adult emergence varied with grain type, percentage of broken grain and the duration following initial infestation. Therefore, minimization of grain damage during milling and other handling processes is recommended to ensure better protection of grains from insect infestation during storage.