EFFICACY OF 3 INSECTICIDES TO CONTROL INSECT PESTS OF STORED SEED CORN

Bagged seed corn treated on 1 November at the rate of 8 ppm AI pirimip hos-methyl formulated from pirimiphos-methyl ULV, pirimiphosmethyl (Ac tellic 5E), chlorpyrifos (Lorsban 3E), or distilled water was stored i n an unheated shed for 10 months. Every 2 mo, the shed was artificiall y infested with the red flour beetle, Tribolium castaneum (Herbst), th e maize weevil, Sitophilus zeamais (Motschulsky), and the Indianmeal m oth, Plodia interpunctella (Hubner). Measured residue deposition at mo th 0 for pirimiphos-methyl ULV, Actellic 5E, and Lorsban 3E was 1.74 /- 0.16, 6.86 +/- 1.06, and 7.08 +/- 1.58 ppm. respectively. After 10 mo, residues had declined to 0.61 +/- 0.07, 2.03 +/- 0.08, and 3.78 +/ - 0.51 ppm, respectively. Insect populations in untreated corn remaine d low throughout the cooler months and began increasing in May (6 mo). At month 10, red flour beetle populations trapped in untreated corn a veraged 83.0 +/- 18.2 adults per 17.25 kg corn, while the maximum in t he three chemical treatments was 11.5 +/- 4.2 adults per 17.25 kg. At month 10, maize weevil populations in untreated corn averaged 643.5 +/ - 381.3 adults per 17.25 kg, with a maximum of only 11.5 +/- 4.2 per 1 7.25 kg in the chemical treatments. Few live Indianmeal moths were det ected in untreated controls or the chemical treatments at month 10. Bo th Actellic 5E and Lorsban 3E are suitable protectants for seed corn.