LIFE RESPONSE OF SITOPHILUS ORYZAE (L.) REARED ON TWO DIETS UNDER DIFFERENT MODIFIED ATMOSPHERES

Protection of grains and their products from insect pests remained a big constraint in the way of future food security. Current study was planned to probe the effective exposure time required to kill adult stages of Sitophilus oryzae (L.) reared on two diets wheat and maize whole grains under six Carbon dioxide (CO2) Modified Atmospheres (MA). Labeled as MA1, MA2, MA3, MA4, MA5 and MA6 at ambient temperature. Twenty insects per replication along with 20 gram diet were released in each exposure chamber. A measured quantity of gas was applied in exposure chamber with the help of syringe having three way stoppers to control the movement of gas. Data was collected by 24 hour time interval up to 144 hours. Results showed that mortality response varied in each diet. Insects reared on maize grains showed more resistance to treatment as compared to wheat grains. Adults of S. oryzae reared on maize grains require a minimum five days exposure time as compared to wheat grains diet that needs only four days exposure period for complete mortality under MA5 with 45% CO2.