Toxic effects of ozone on selected stored product insects and germ quality of germinating seeds

The merchant grain beetle (MGB), Oryzaephilus mercator (Fauvel), the cigarette beetle (CB) Lasioderma serricorne (F.) and the rice weevil, Sitophilus oryzae (L.) cause significant damage to stored grain, grain-based products, and other durable commodities. Ozone, a highly oxidative toxic gas, has the potent to kill insects, meantime degrades rapidly to oxygen, making it a potential alternative to phosphine, a fumigant to which insects are developing resistance. The adults of MGB and CB were exposed to ozone concentrations of 100 400 ppm at 50 ppm increments for one hour and at 100 ppm for 1-6 h. Adults of rice weevil buried at 5, 15 or 25 cm depths within a wheat mass placed in 10 cm diameter 30 cm high PVC pipes were exposed to ozone concentration of 200 ppm for six hours and then at 12-h increments up to 60 h. Adult survival was recorded at 0, 24, and 48 h post-treatment. Significantly fewer MGB or CB adults survived when exposed to higher ozone concentrations or when exposed to ozone in the absence of food. RW adult mortality at 5 cm depth were significantly higher than that of 15 or 25 cm depths. This paper further discusses about mortality of MGB, CB and RW adults at different exposure periods at various ozone concentrations and effect of ozone on wheat germination.