Laboratory Evaluations of Methyl Bromide and Carbon Dioxide Mixture Against Twospotted Spider Mite, 1996

The potential of carbon dioxide to reduce the dose of methyl bromide required to kill mites during 3-h fumigations was evaluated. Fumigations were performed in modified 2.5-liter desiccator jars with methyl bromide alone or with 5% carbon dioxide at concentrations of 0, 8, and 24 mg/liter at 27° C and 60% RH. Three to five leaf discs (14 mm diam) infested with eggs, nymphs, and adults were placed in the fumitoria and allowed to acclimate for 4 h after which the appropriate treatment dose was added. Doses were confirmed by gas chromatography. Treatment doses were calculated by averaging the dose at the beginning of the exposure period with that at the end of the exposure period. Two to six replicates were run, each on a different day, during Feb and Mar. Following fumigation, leaf discs were removed from the fumitoria, held in petri dishes for 24 h, and mite mortality was assessed.