Molecular insights into water balance disruption as a pest control strategy for Rhyzopertha dominica (F.)

Abstract

Rhyzopertha dominica (Fabricius), the lesser grain borer, is a major pest of stored grains and causes significant economic losses globally. Inert dust, an environmentally friendly insecticide, can cause rapid water loss and death in insects by disrupting the cuticular waterproof barrier. Its successful application highlights the potential of targeting the water balance as an effective pest control strategy, especially in dry storage environments. However, research on the molecular mechanisms of stored-product insects under inert dust or direct desiccation conditions is limited. In the present study, we assessed the lethal effects of inert dust (LC₅₀ = 0.606 g/m²) and desiccation (LT₅₀ = 6.208 d) on R. dominica. Subsequently, a high-quality gene set containing 14,363 protein-coding sequences was obtained through genome annotation. Comparative transcriptome analysis of the two treatments was conducted by mapping to a reference gene set, followed by RT-qPCR validation. The analysis revealed a substantial overlap in the DEGs between the two treatments. Among these, 141 upregulated genes were primarily involved in processes such as fatty acid elongation, uric acid metabolism, and phospholipid metabolism, whereas 183 downregulated genes were mainly associated with nutrient absorption, detoxification, and hormone regulation, reflecting an energy trade-off in R. dominica under stress conditions. Moreover, multiple key enzyme genes that participate in cuticular hydrocarbon biosynthesis were significantly upregulated, suggesting a critical role for this process in water stress adaptation. These findings provide valuable resources for molecular research on R. dominica and offer insights into the development of pest management strategies targeting insect water balance mechanisms.