Evaluation of fumigant toxicity of cyclohexanone to 5 species of insect pests

Cyclohexanone is a major precursor for nylon production and is also used as a pesticide solvent. In this study, cyclohexanone was evaluated as a fumigant against rice weevil adults, confused flour beetle adults, western flower thrips larvae and adults, spotted wing drosophila adults, and subterranean termite workers. Cyclohexanone fumigation was effective against all 5 insects, and there were considerable variations in susceptibility to cyclohexanone fumigation among the 5 species. At 20 degrees C, complete control of spotted wing drosophila adults was achieved in 1-h fumigation with 25 mu l/l of cyclohexanone and complete control of eastern subterranean termite workers was achieved in 3-h fumigations with 50 mu l/l dose of cyclohexanone. Stored-product insects confused flour beetle, and rice weevil adults were more tolerant to cyclohexanone fumigation. Fumigations of 24 h with 75 mu l/l dose of cyclohexanone caused 100% mortality of rice weevil adults and 98% mortality of confused flower beetle adults. Even at a 100 mu l/l dose, the 24-h fumigations did not achieve 100% mortality of confused flour beetle adults. At 5 degrees C, complete control of western flower thrips was achieved in 3- and 6-h fumigations with 100 and 50 mu l/l doses of cyclohexanone, respectively. Cyclohexanone vapor concentrations were measured using cyclohexanone detector tubes. Vapor concentrations were far below the expected saturation concentration indicating that most cyclohexanone did not exist as vapor in fumigation chambers. The results of effective control of all 5 insect species suggest that cyclohexanone has the potential to be used as a fumigant for postharvest pest control.