The lethal effects of diatomaceous earth and aqueous-methanolic neem extract, Melia azedarach as a single and mixed application on Tribolium confusum and Callosobruchus maculatus

Evaluation of single and integrated effects of diatomaceous earth and neem fruit extract, Melia azedarach, against 1-to-3-day-old insects of flour weevil, Tribolium confusum (Col., Tenebrionidae) and cowpea seed beetle Callosobruchus maculatus (Col., Chrysomelidae). Three replications were performed by contact toxicity by filter paper residue test and the mortality was measured 24 and 48 hours later. After 48 hours interval, the LC50 level of Permaguard® formulation of diatomaceous earth against flour weevil was 4.6 times less than 24 hours interval. In the case of other species, this amount decreased by 3.2 times. Over time, from 24 to 48 hours intervals, the effect of the neem extract on both species increased. Also, there was a synergistic relationship between neem fruit extract and diatomaceous earth in both species and both times studied, which increased with increasing exposure time. Therefore, the simultaneous use of these two compounds could improves the effectiveness of these compounds.