Evaluation Of Three New Insecticide Formulations Based On Inert Dusts And Botanicals Against Four Stored-Grain Beetles

Three new insecticide formulations were developed that combine diatomaceous earth (Celatom MN 23) with compounds with low mammalian toxicity. Sitophilus oryzae, Sitophilus granarius, Rhyzopertha dominica and Tribolium castaneum were held on wheat (13.5% moisture content) treated with different doses of the formulations at 28 +/- 1 degrees C and 60 +/- 5% RH for 2-7 days, and then held for progeny emergence. The three formulations were made up of: dill essential oil, bait, silica gel and DE (Dill-DE); pyrethrin, PBO, dill essential oil, silica gel and DE (Py-Dill-DE); and disodium octaborate tetrahydrate (DOT), pyrethrin, PBO, dill essential oil, silica gel and DE (DOT-PY-Dill-DE). They were applied either as powders or as slurries. Applying the formulations as powders over a range of concentrations showed that pure DE is the least effective insecticide, with 50% mortality ranging from 430 to 1000 ppm depending on the species after 2-3 days. Dill-DE formulation was the next least effective formulation. The Py-Dill-DE and DOT-Py-Dill-DE formulations had similar activity and being the most effective formulations with 50% mortality from 40 to 260 ppm depending on the species. Bioassays were also run at single doses. Dill-DE was applied at 300 ppm, Py-Dill-DE at 150 ppm and DOT-PY-Dill-DE at 200 ppm. After 3 days, Py-Dill-DE and DOT-PY-Dill-DE formulations there was 100% mortality for S. oryzae, S. granarius and R. dominica. After 7 days the mortality of T. castaneum was from 96 to 100%. Both formulations reduced the progeny almost by 100%. There was survival for all insects with Dill-DE formulation. The concentrations of 150 ppm of Py-Dill-DE, 200 ppm of DOT-PY-Dill-DE and 300 ppm of Dill-DE reduced bulk densities by 0.7, 0.8 and 5.7 kg/hL, respectively. Crown Copyright (C) 2020 Published by Elsevier Ltd. All rights reserved.