Can environmental DNA be used within pest insect agricultural biosecurity? Detecting khapra beetle within stored rice

Abstract

The khapra beetle (Trogoderma granarium) is among the most damaging stored-product pests worldwide and a high priority for agricultural biosecurity surveillance. We developed a method for detecting khapra beetle environmental DNA (eDNA) deposited in stored grain: washing a rice sample, filtering the wash water, and screening for beetle DNA via quantitative PCR. This approach detected the equivalent of a single khapra beetle larva within a 50 kg container of rice with 85% to over 97% certainty, depending on whether one or three qPCR technical replicates were performed, demonstrating eDNA’s potential as a sensitive tool for stored-product pest surveillance.