Environmental RNAi in herbivorous insects

Area of Science:

• Molecular Biology
• Entomology
• Genetics

Background:

• Environmental RNA interference (eRNAi) uses exogenous double-stranded RNA (dsRNA) to regulate gene expression.
• Previous studies focused on artificial conditions, leaving natural eRNAi effects unknown.

Purpose of the Study:

• Investigate exogenous dsRNA uptake and eRNAi under natural insect feeding conditions.
• Determine factors influencing eRNAi efficacy in sensitive and recalcitrant insects.

Main Methods:

• Analyzed dsRNA and small RNA content in coleopteran and lepidopteran larvae fed on wild-type plants.
• Utilized RNA sequencing to assess siRNA abundance and effects on insect transcriptome.

Main Results:

• Coleopteran insects showed uptake and processing of plant long dsRNAs into siRNAs.
• Lepidopteran insects, recalcitrant to eRNAi, did not accumulate plant-derived siRNAs.
• dsRNA stability in the gut and uptake facilitated eRNAi, but low siRNA abundance limited measurable effects.

Conclusions:

• Broad dsRNA uptake and siRNA processing occur in sensitive insects naturally.
• dsRNA stability, uptake, and sufficient siRNA dosage are crucial for effective eRNAi.
• Lack of amplification mechanisms and low siRNA abundance may hinder significant gene regulation in some insects.