Layered double hydroxide nanosheets for improving RNA interference efficiency in the diamondback moth, Plutella xylostella

Since its discovery, RNA interference (RNAi) has piqued interest as a new method for controlling insect pests. However, one of the hurdles still facing the development of RNAi-based  pest management strategies is the variability of RNAi efficiency across insect orders. This variability is caused by many factors including degradation and poor cellular uptake of interfering RNA molecules. One method to protect the interfering RNA molecules from degradation and promote cellular uptake is the utilization of nanomaterials. One such nanomaterial includes layered double hydroxide (LDH) nanosheets, which have previously been used to improve RNAi efficiency in other more RNAi susceptible insect species. Typically, insect RNAi experiments employ long double stranded RNA (dsRNA) as the interfering RNA molecule; however, the structure of the RNA molecules may also influence the efficiency of RNAi. Hairpin RNA polymers (HRP) are formed of multiple repeated hairpin RNAs, and because of their complex structure, could  improve the efficiency of RNAi in the most RNAi refractory insect group, Lepidoptera. In this study, we synthesized LDH nanosheets bound with HRP or dsRNA targeting genes of interest for pest control in the diamondback moth, Plutella xyllostella. We assessed the stability of the nanosheets in the moth midgut and hemolymph. We also examined the RNAi efficiency in the diamondback moth larvae using the leaf disc bioassay method. These new technologies could be applied in the development of more efficient RNAi-based bioinsecticides for the control of lepidopteran pests.