Efficacy of ethiprole applied alone and in combination with conventional insecticides for protection of stored wheat and stored corn

The insecticidal pyrazole ethiprole, applied at rates of 7.5 and 10.0 ppm either alone or in combination treatments with deltamethrin, piperonyl butoxide, and chlorpyrifos-methyl, was evaluated as a protectant of stored wheat and stored corn. The commodities were treated with six treatment combinations, including in untreated control, and held for 6 mo at 22, 27, or 32degreesC and 57% RH. Bioassays were conducted monthly by exposing the rice weevil. Sitophilus oryzae (L.), and the red flour beetle, Tribolium castaneum (Herbst), on treated wheat and the maize weevil, Sitophilus zeamais (Motschulsky), and the red floor beetle on treated corn. The storage temperature of wheat did not significantly affect mortality of exposed insects (P greater than or equal to 0.05). All rice weevils were dead after 1 wk in all treatments, and no F-1 adults were produced. Mortality of red flour beetles was not dependent on either chemical treatment or bioassay month, and no F-1 adults were produced. The storage temperature of corn did not significantly affect mortality of exposed insects (P greater than or equal to 0.05). Mortality of maize weevils varied from 77.9 to 100% in all chemical treatments, and no F-1 adults were produced. Mortality of red flour beetles was also variable among treatments and bioassay month and no F-1 adults were produced. This is the first published report of a study in which pyrazoles have been evaluated against stored-grain insects.