Maize Weevil Control, 1987

Abstract

Abstract In Test 1, 19 treatments were applied to uninfested grain of‘Across 8363 QPM’ maize (11% moisture) in December 1986. Each treatment consisted of 1.0 kg of grain, divided into 4 replicate batches of 250 g each in pint glass jars (lids ventilated with screen apertures). They were held at 25 ± 1°C and 60-80% RH. Each replicate jar was infested with 50 ± 2 newly emerged, unsexed weevils 10 DAT, and mortality was recorded after a 7-d exposure period. The treatments with high initial mortality were reinfested with 50 ± 2 weevils/jar 3 months after treatment. Treatments giving only partial or no control were maintained with only the initial infestation. Effective treatments were again reinfested at 6 and 9 months after treatment to check on persistence of control. Between intervals, seeds were moved to Poza Rica, Mexico (a humid lowland tropical area), to simulate field conditions. Eleven months after treatment, the percentage of germination (in greenhouse flats, 4-cm soil cover) was determined to assess possible phytotoxic effects on seed and reduction in germination as a result of weevil damage to grain. In Test 2, to simulate the situation of field infested grain, weevils were allowed to feed and lay eggs on 20 kg of‘Across 8363 QPM’ maize grain (12.5% moisture) for 14 d. Then, the same 19 treatments used in Test 1 (1.0 kg grain/treatment split into 4 replicates) were made. At 40 DAT, the number of adult weevils emerged in each treatment was recorded.