Doğa Cedden, Gözde Güney
Insects produce diverse small RNAs (sRNAs) that play important roles in gene regulation and immunity, and some are being exploited as species-specific pest control strategies. Here, we review recent advances in insect sRNA biology. First, we summarize the canonical classes, microRNAs (miRNAs), small interfering RNAs (siRNAs), and PIWI interacting RNAs (piRNAs). Next, we highlight emerging functions for transfer RNA derived sRNAs (tsRNAs) in development and stress responses. We highlight that mechanistic studies are now beginning to link sRNAs to various biological phenomena using methods such as RNA sequencing and degradomics in combination with functional validations. We outline design features that increase the efficacy of double stranded RNA (dsRNA) derived siRNAs and note that siRNAs appear to play a limited part in transposon control compared with piRNAs. We discuss emerging roles of piRNAs in reproduction and sex determination that suggest potential pest control strategies. Lastly, we highlight emerging evidence for cross-kingdom miRNAs delivered by insects to plants to facilitate herbivory, and conversely, plant miRNAs that may be transferred to insects to regulate their physiology. Overall, we argue that our understanding of insect sRNAs is rapidly expanding, which has implications for novel pest management strategies. • miRNAs guide degradation & translational inhibition to regulate various processes. • siRNAs suppress viruses, affect RNAi efficacy, but only minorly control transposons. • piRNAs protect against transposons, important for fertility, and sex determination. • tRNA-derived sRNAs may be regulating development and suppression of translation. • Cross-kingdom miRNAs may mediate plant-insect interactions in both directions.