Delivery of lethal dsRNAs in insect diets by branched amphiphilic peptide capsules

Development of new and specific insect pest management methods is critical for overcoming pesticide resistance and collateral off-target killings. Gene silencing by feeding dsRNA to insects shows promise in this area. Here we described the use of a peptide nano-material, branched amphiphilic peptide capsules (BAPCs), that facilitates cellular uptake of dsRNA by insects through feeding. The insect diets included dsRNA with and without complexation with BAPCs. The selected insect species come from two different orders with different feeding mechanisms: Tribolium castaneum and Acyrthosiphon pisum. The gene transcripts tested (BiP and Armet) are part of the unfolded protein response (UPR) and suppressing their translation resulted in lethality. For Acyrthosiphon pisum, ingestion of BiP-dsRNA associated with BAPCs led to the premature death of the aphids (t(1/2)=4-5 days) compared to ingestion of the same amounts of free BiP-dsRNA (t(1/2)=11-12 days). Tribolium castaneum was effectively killed using a combination of BiP-dsRNA and Armet-dsRNA complexed with BAPCs; most dying as larvae or during eclosion (similar to 75%). Feeding dsRNA alone resulted in fewer deaths (similar to 30%). The results show that complexation of dsRNA with BAPCs enhanced the oral delivery of dsRNA over dsRNA alone.