Efficacy of pirimiphos-methyl, deltamethrin, spinosad and silicoSec against adults and larvae of Tenebrio molitor L. on wheat, barley and maize

Abstract

The yellow mealworm beetle, Tenebrio molitor L. (Coleoptera: Tenebrionidae) is a noxious insect that causes serious damages to stored products worldwide. In the present study, pirimiphos-methyl, deltamethrin, spinosad and silicoSec were evaluated as grain protectans against adults, small and large larvae of this species on wheat, barley and maize at label doses. Mortalities were estimated after 1, 3, 7 and 14 days of exposure. All tested insecticides were able to control T. molitor adults. Complete (100%) mortality of adults was noted after 14 days of exposure on wheat and maize treated with pirimiphos-methyl or silicoSec and barley treated with pirimiphos-methyl, silicoSec and spinosad. Larvae were more tolerant than adults to insecticidal treatments. However, pirimiphos-methyl caused high levels of mortality to small larvae that were 71.1, 91.1 and 60% on wheat, barley and maize respectively after 14 days post exposure. The type of commodity played a significant role on the performance of the tested insecticides. Mortality was higher on barley and wheat than on maize for all tested stages and insecticides. Our results indicate that the life stage of T. molitor and the type of commodity should be taken into account for the management of this species.