Combining Natural and Microbial Insecticides with Diatomaceous Earth for Effective Management of Prostephanus...

Prostephanus truncatus is well known for causing extensive postharvest losses and threatening food security in tropical and subtropical regions. The reliance on synthetic insecticides has raised concerns about the development of resistance, environmental safety, food contamination, and human health, emphasizing the need for alternative management strategies. Thus, the present study evaluated the insecticidal efficacy of diatomaceous earth (DE) in the Protector formula alone and in combination with spinosad, abamectin, or the entomopathogenic fungus Beauveria bassiana against P. truncatus adults and their progeny production on maize under two temperatures (25 and 30 °C) at low concentrations. Bioassays revealed that DE or B. bassiana alone induced low mortality, while spinosad and abamectin single applications resulted in high mortality rates, achieving 100% after 21 days of exposure at 30 °C at the higher concentrations. The combined applications of spinosad or abamectin with DE resulted in complete mortality and progeny suppression at lower concentrations at 25 °C. Temperature had a significant influence in some cases. Overall, these findings demonstrate that DE, when combined with other natural insecticidal agents at low concentrations, especially spinosad and abamectin at specific temperatures, can provide highly effective control of P. truncatus, offering a promising strategy for integrated pest management (IPM) in stored maize.