CARBON DIOXIDE AS A FUMIGANT TO REPLACE METHYL BROMIDE IN THE CONTROL OF INSECTS AND MITES DAMAGING STORED PRODUCTS AND ARTEFACTS

Abstract:
Mixed stage cultures of Sitophilus oryzae (L.), Tribolium castaneum (Herbst), Liposcelis bostrychophila Badonnel, Tyrophagus putrescentiae (Schrank) and Acarus siro L. were placed inside, between and under 32kg sacks in a one tonne stack of bagged flour and exposed to 60% carbon dioxide in a fumigation 'bubble' for 4,7 or 14 days at about 20°C. T. putrescentiae survived 14 days exposure. Complete control of T. castaneum required 7 days exposure; S. oryzae, L. bostrychophila and A. siro required 14 days. Burial within the flour stack apparently did not significantly impede the penetration of carbon dioxide to the buried cultures. The flour stack was preheated by circulating warn air (22-29°C) around it. The temperature inside a bag in the lower part of the stack took 120 hours to rise from 11°C to 20°C. Free air space temperature near the stack centre responded similarly. The use of carbon dioxide to control insects and mites infesting commodities (other than bulk grain) and artefacts, and its limitations as a structural fumigant, are discussed.