Response of pests of flour mills to high temperatures in the presence and absence of 10 percent carbon dioxide

摘要

The effect of high temperatures was assessed against 10 pest species of flour and flour mills, Ephestia kuehniella, Tribolium castaneum, T. confusum. Cryptolestes turcicus, Ptinus tectus, Sitophilus granarius, Gnatocerus cornutus, Tenebrio molitor,Liposcelis bostrychophila and Acarus siro. Some tests were run with the addition of 10 percent carbon dioxide (CO_2). For S. granarius, the effect of the CO_2 at 40 deg C was highly beneficial. Target temperatures were reduced by several degrees or the times required for complete kill were shortened from two or three days to within the 24-h limit targeted for flour-mill treatments. For Tribolium confusum, the addition of CO_2 at 40 deg C or above had little effect on older stages in reducing survival, although the exposure time permitting survival was brought to within three days for younger stages. At 44 deg C, the presence of 10-11 percent CO_2 in the heated atmosphere seemed to adversely affect the effectiveness of combined exposures against severalspecies, with increased levels of survival and longer times being required for complete control over those for heat alone. The most heat-tolerant species, T. castaneum, survived 48-h exposures at 44 deg C, survival increasing from 1 percent to 10 percent when CO_2 at 11 percent was added to the atmosphere. This species required a temperature of 48 deg C to achieve complete kill of all stages within 24 hours.