Residual efficacy of thiamethoxam, Beauveria bassiana (Balsamo) Vuillemin, and diatomaceous earth formulation against Rhyzopertha dominica F. (Coleoptera: Bostrychidae)

Abstract

The residual efficacy of diatomaceous earth alone and in combination with Beauveria bassiana (Balsamo) Vuillemin or a neonicotinoid insecticide thiamethoxam against Rhyzopertha dominica (Coleoptera: Bostrychidae) was studied under laboratory conditions. The mortality of adult R. dominica was decreased over the 9 months of storage period and the combined application of the test materials enhanced the mortality rates compared with alone treatments. The greatest mortality was observed in the combination of DE with thiamethoxam. Progeny suppression was decreased with the extended storage period. The maximum rate of mycosis and sporulation in the cadavers of R. dominica was observed where B. bassiana was applied alone at the lowest-dose rate. The results of this study indicate that all three control measures may provide safety for an extended period of time against R. dominica.