POSSIBLE NEW INSECTICIDES IN THE PROTECTION OF STORED WHEAT

Z. Korunic, R. Almasi, D. Posloncec

Abstract: With the aim of the efficient control of pests and significant decrease in insecticide residues in stored goods, some new formulations of powder insecticides have been developed by combining natural and synthetic substances. The developed formulations are as follows: the mixture of diatomaceous earth (DE) and deltamethrin (DM (DE/DM) containing 900g/kg of DE and 1g/kg of DM active substance (a.s.), DE and pyrethrin (Py) (DE/Py) containing 900g/kg of DE and Py 10g/kg a.s. and DE and spinosad (Spin) (DE/Spin) containing 900g/kg of DE and 10g/kg a.s. of spinosad. The goal of this research work was the evaluation of the efficiency of formulations DE/DM, DE/Py and DE/Spin in the control of Sitophilus oryzae L. and Rhizopertha dominica F. on wheat. In the experiments, the wheat variety Pobeda grown in Vojvodina (Serbia) in 2011, containing 12.12% moisture content was used. The applied doses (ppm or grams per 1000 kg of grain) were: DE/DM and DE/Spin - 50, 100 and 150, DE/Py -100, 200 and 300. The experiments were carried out at the temperature from 25 to 280C and air humidity (r.h.) of 65 to 80%. The results of the efficiency were evaluated after 7, 14 and 21 days of the exposure of insects to the treated wheat and the effects on the offspring after 66 days (S. oryzae) and after 70 days (R. dominica). The doses of DE/DM (150 ppm) and DE/Py (200 ppm) caused 100% mortality of S. oryzae during 14 days of the exposure to treated wheat and completely suppressed its offspring. However, the highest researched dose of DE/Spin of 150 ppm during 21 days controlled S. oryzae by
98.5% and reduced its offspring by 92%. The lowest doses of all the three formulations (50 ppm of DE/DM and DE/Spin and 100 ppm of DE/Py) controlled the imagoes and offspring of R. dominica by 100%. In the conditions under which the experiment was carried out the recommended doses for S. oryzae control on wheat can be 150 ppm of DE/DM, 200 ppm of DE/Py and probably 200 ppm of DE/Spin, and for the control of R. dominica the lowest doses of all the three formulations.

Keywords: deltamethrin; diatomaceous earth; insecticide mixture; pyrethrin; Rhyzopertha dominica; Sitophilus oryzae; spinosad; stored wheat

Date published: 2019-01-28