Gene

microRNA

Plutella

Biotechnology

Bacteria

Biology

PEST analysis

Bt cotton

Botany

Computational biology

Helicoverpa armigera

Larva

Genetics

Toxicology

Agronomy

Exigua

Bacillus thuringiensis

Integrated pest management

Recombinant DNA

Spodoptera

Insecticide resistance

Journal of Pest Science

The management of economically important lepidopteran pests has relied heavily on chemical and Bt-bio pesticides since 1940s, which has led to multiple recurring issues in resistance and environment. In this study, to search for a genetic-based control alternative with a distinctively different mode of action, we carried out a toxicological characterization of miR-34-5p, a highly conserved lepidopteran microRNA targeting EcR. Integrating target site prediction, co-localization of miRNA and EcR by fluorescence in situ hybridization, luciferase reporter assays as well as the gain-of-function and loss-of-function experiments, we comprehensively examined the physiological function and insecticidal properties of miR-34-5p among three representative lepidopteran pests, including Helicoverpa armigera, Spodoptera exigua, and Plutella xylostella. The combined results confirm a conserved role of miR-34-5p in the regulation of EcR in multiple lepidopteran pests. Overexpression or knocking down of miR-34-5p through both injection and feeding leads to insecticidal phenotypes, including high mortality, low fecundity, and developmental defects, suggesting that miRNAs can be considered as novel molecular targets in general, miR-34-5p for lepidopteran pests in particular. These results highlight the importance of miR-34-5p in the regulation of EcR expression in lepidopteran insects and provide a solid foundation for development of miRNA-based green pest control technology.

miR-34-5p, a novel molecular target against lepidopteran pests