Insecticidal Efficacy of Some Turkish Diatomaceous Earth Deposits Against Rice Weevil, Sitophilus oryzae L. (Coleoptera:Curculionidae) on Paddy

Abstract

In this study, the insecticidal effect of 4 different Turkish diatomoceus earth (DE) were tested against the rice weevil, Sitophilus oryzae L. on paddy rice. Paddy rice was treated at 100, 300, 500, 900 and 1500 ppm (mg DE/kg paddy rice) concentrations of four Turkish diatomaceous earths (AGN-1, ACN-1, FB2N-1 and CCN-1) and commercial diatom earth (Silicosec). Paddy rice samples were mixed with DE and then filled into 100 ml glass vials. Rice weevil adults (<14 days) were transferred into the vials and the vials were covered with fine mesh. The experiments were carried out at 25±1 °C temperature, 55% RH in dark conditions under laboratory conditions. After 7, 14, 21 days of treatment the mortality rates of S. oryzae adults and progeny production numbers (F1) were recorded. AGN-1 diatomaceous earth at 300 ppm and higher concentrations produced 100 % adult mortality on the 7th days after treatment while other DE's caused 1.4- 97.7% mortality even at the highest concentration (1500 ppm). After 14 days of the treatments, 100 ppm concentration of AGN-1 produced 98.5 % mortality, while 900 and 1500 ppm concentration of ACN-1 caused 100% mortality. Other DE's, CCN-1 Silicosec and FB2N-1, at 1500 ppm concentration produced 97.3, 96.6 and 42 % of mortality respectively. After 21 days of the treatments, AGN-1 caused 100% mortality at all concentrations while ACN-1 at 900 and 1500 ppm, CCN-1 and Silicosec and FB2N-1 at 1500 ppm produced 100%, 100% and 93.9% mortality respectively. AGN1 was totally hindered progeny production. It has been determined that the differences between th insecticidal activities of tested DEs on stored product insects could be attributed to different physical properties of DE samples taken from different locations of Turkey. In this study it was determined that diatomaceous earth with high SiO2 ratio (FB2N-1) had low insecticidal efficacy against tested insect. On the other hand, of DEs with similar particle size (AGN-1, FB2N- 1) were determined to have significant differences in their efficacy against S. oryzae. In conclusion, this study indicated that Turkish diatomaceous earth, AGN-1 showed higher insecticidal efficacy against S. oryzae on paddy rice than commercial DE, Silicosec and can potentially be used as a grain protectant for control of S. oryzae on paddy rice. © 2022 Namik Kemal University - Agricultural Faculty. All rights reserved.