Oral
RNAi
reduces survival and grain loss in
Rhyzopertha dominica
, including phosphine‐resistant populations
ZiHan Shen, Wei Chen, KangXu Wang Abstract
BACKGROUND
Phosphine fumigation remains a cornerstone of stored‐grain protection, yet widespread resistance in Rhyzopertha dominica threatens its long‐term effectiveness. RNA interference (RNAi) through ingestion of double‐stranded RNA (dsRNA) offers a sequence‐specific mode‐of‐action (MoA) distinct from conventional insecticides. However, practical development requires identification of orally effective target genes, demonstration of grain‐protection benefits, and validation of efficacy in phosphine‐resistant populations.
RESULTS
Oral delivery of dsRNA produced dose‐dependent reductions in adult survival, with survival ranging from 3% to 12% among the five target‐gene treatments at 300 ng μL –1 after 10 days of continuous exposure, compared with >90% in the controls. Target transcript levels were reduced to 15–48% of control levels following dsRNA exposure, confirming RNAi activity. dsRNA treatment also substantially reduced grain damage, with relative grain weight loss reduced to as low as 8% of the water‐treated control at 300 ng μL –1 . Oral RNAi remained effective across populations with different levels of phosphine resistance, with corrected mortality reaching ≈82% by Day 10 in the highly resistant population (RR = 1173.63).
CONCLUSION
Oral RNAi can suppress R. dominica populations and reduce grain damage while maintaining efficacy in phosphine‐resistant populations under the conditions tested. These findings support RNAi as a complementary MoA that may help diversify management options for stored‐grain protection and resistance management. © 2026 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.