Fumigation of Tribolium confusum Adults with 80:20 (CCI1:CS2) During Carbon Dioxide- Or Nitrogen-Induced Respiration Elevation or Depression

Abstract

Individual lots of 100 2-week-old adults of the confused flour beetle, Tribolium confusum (Jacquelin duVal), were exposed to dry, flowing (100 cc per min) carbon dioxide or nitrogen and then fumigated for 24 hours in an LC50 atmosphere of 80:20 mixture (CCI4:CS2 by volume) at 30°C. Previous studies indicated that ½-hour exposures to either CO2 or N2 produced extreme respiration depression. Two-hour exposures to CO2 or N2 followed by I-hour and ½-hour recovery periods, respectively, induced maximum respiration rates. When insects were fumigated at minimum respiration (no recovery period permitted) the resulting mortality was greater than the additive effect of the individual preconditioning and fumigated treatment mortalities. Nitrogen exerted a greater synergistic effect than did carbon dioxide, No increased susceptibility to fumigant was noted when the insects were fumigated during peak respiration in the recovery period following CO2 or N2anoxia. In a control series, 4 replications of the following insect lots were evaluated: neither treated nor fumigated, fumigated but not treated, air-treated (100 cc per min, 2 hours) but not fumigated, and both air-treated and fumigated. Mortality of insects air-treated but not fumigated was more than 3% greater than natural mortality and was statistically significant. These data suggest that dry airflow produced stress in adult confused flour beetles.