Mortality of adult Cryptolestes ferrugineus (Stephens) exposed to changing CO2 concentrations

The concentration of carbon dioxide (CO(2)) in a grain bin declines during a fumigation due to leakage, but mortalities of adult Cryptolestes ferrugineus (Shephens) have been obtained and reported at constant CO(2) concentrations. A procedure for predicting the mortality of adult C. ferrugineus exposed to conditions of changing CO(2) concentration was developed. Based on published data, a regression equation was obtained for mortality of adult C. ferrugineus exposed to elevated CO(2) concentrations at a temperature of 25 degrees C. The regression equation was used go calculate a cumulative lethality index. Complete mortality should occur when the cumulative lethality index equals one. Agreement between the observed insect mortality and the corresponding cumulative lethality index was good in five experimental fumigations conducted in sealed, welded-steel hopper bins, but the cumulative lethality index over-predicted the insect mortality in the sixth experimental fumigation. (C) 1999 Elsevier Science Ltd. All rights reserved.