Toxicity of carbonyl sulfide to stored product insects

In laboratory tests, carbonyl sulfide was toxic to 5 species of stored-product insects. At the LC50, the most susceptible insects in order of decreasing susceptibility were larval navel orangeworm, Amyelois transitella (Walker); adult sawtooth grain beetle, Oryzaephilus surinamensis (L.); adult driedfruit beetle, Carpophilus hemipterus (L.); adult cigarette beetle, Lasioderma serricorne (F.); and adult confused flour beetle, Tribolium confusum Jacquelin duVal. Posttreatment end-point mortality was immediate for L. serricorne adults (1 d) but was delayed for O. surinamensis adults (2 d) and C. hemipterus and T. confusum adults (3 d). Susceptibilities of life stages of T. confusum, the most tolerant species of those tested, varied. The egg and pupal stages were least susceptible, requiring concentration times time products of 1,008 and 750 mg/liter/h, respectively, for a LC99.9 during a 24-h exposure period. Based on pest toxicity, carbonyl sulfide has potential for use as a fumigant of dried fruits and nuts