Enhanced Effectiveness of Vacuum or CO₂ in Combination with Increased Temperatures for Control of Storage Insects
S. NAVARRO¹, S. FINKELMAN¹, G. SABIO², A. ISIKBER³, R. DIAS¹, M. RINDNER¹ and A. AZRIELI¹
¹Department of Stored Products, Agricultural Research Organization, The Volcani Center, P.O.Box 6, Bet Dagan 50250, Israel
²Bureau of Postharvest for Research and Extension, Department of Agriculture, Nueva Ecija, Philippines
³Department of Plant Protection, Faculty of Agriculture, University of Kahramanmaras Sutcu Imam, Kahramanmaras 46060, Turkey
Corresponding author:
Abstract: Laboratory studies were carried out to identify the combinations that enhance the effectiveness of insect control based on vacuum or CO₂ in combination with increased temperatures as a quarantine treatment of storage pests. The roles of the commodity moisture content and the partial pressure of oxygen on the effectiveness of vacuum were described. For T. castaneum, E. cautella and P. interpunctella the egg stage was the most resistant to low pressure, the times needed to obtain LT99 were 22, 45 and 49 h, respectively. For T. castaneum the larva and adults were the most susceptible stages with an LT₉₉ of 7 h; for E. cautella and P. interpunctella the adult was the most susceptible stage with LT₉₉ times of only 6 h and 5 h. The effect of CO₂ at 45°C on reducing the exposure time for diapausing larvae of T. granarium showed that by increasing the CO₂ concentration to 90% the LT₉₉ value decreased to about 10 h, whereas at 35ºC the LT₉₉ value was 29 h. Ephestia cautella larvae were shown to be the most resistant stage to 90% CO₂ at 40°C, with an LT₉₉ value of only 6 h. For Oryzaephilus surinamensis under the same conditions, the LT₉₉ value was 9 h for the most resistant egg stage. These encouraging results led to the idea of developing a transportable flexible storage system to render the technology a practical tool for the control of insect pests. Experiments were carried out using a 15-m³ capacity plastic container termed the “Volcani Cube™” or “GrainPro Cocoon™”. Bioassays in field trials at 30°C demonstrated that complete mortality of test insects composed of all four developmental stages of E. cautella and Tribolium castaneum, was observed upon 3- days exposure to vacuum maintained between 23 and 75 mm Hg.
Key words: methyl bromide alternatives, vacuum, CO₂, storage insects, transportable systems
