Chlorine dioxide fumigation to control stored product insects in rice stored in a room

Gaseous chlorine dioxide (ClO₂) was applied to fumigate larvae and adult stages of Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae) and Sitophilus zeamais (Motschulsky) in rice grain bags stored in a grain storage room. It was confirmed that the fumigation efficiency varied depending on the storage position and insect life stage and species. The fumigation effect was the highest on the surface of the grain bag and lowest on the middle of the outer position on the grain storage bag. The mortality of adult P. interpunctella, 5 days after ClO₂ fumigation, reached 100% regardless of their position, whereas that of the larva P. interpunctella and adult S. zeamais varied depending on their positions. The mortalities in the outer portions of the grain bag were the highest, followed by that at the top of the grain bag. The ClO₂ residue of treated rice were lower than that accepted by international standards. To achieve fumigation effectiveness which similar with lab scale experiment, more researches which are related to infiltration or circulation of gaseous ClO₂ are needed.