Designing Nanocarriers Around Insect Barriers: An Evidence Map for Double-Stranded RNA Delivery

Nanocarriers are increasingly used to improve double-stranded RNA (dsRNA) delivery for insect functional genomics and pest management, but material-centered comparisons do not explain why similar formulations succeed in one species or exposure route and fail in another. Building on previous barrier-guided and polymer-focused reviews, this evidence map re-analyzes primary insect studies at the level of traceable delivery claims. A structured search through July 31, 2026 identified 41 eligible primary reports, which were mapped against route-dependent processes leading from exposure to intracellular availability, RNAi processing, and phenotype. Claim-specific appraisal profiles recorded formulation integrity, causal controls, molecular validation, and biological validity as separate domains. Chitosan, lipids, layered double hydroxides, cationic polymers, carbon materials, peptides, and porous frameworks can improve particularly measured delivery outcomes, but the evidence does not establish a universally superior carrier. Several characterized formulations improved stability, plant movement, tissue distribution, or uptake without establishing target-gene knockdown or linked phenotype, showing that physicochemical performance is not sufficient evidence of functional RNA interference. Nanocarriers were most defensible when tested against matched naked-dsRNA or non-nanocarrier comparators and when route-relevant integrity, sequence-specific silencing, and phenotype were demonstrated in the same experimental context. The proposed barrier map and claim categories are organizing tools for diagnosing delivery gaps; they require prospective validation before predictive use.