Fig. 2.

Regulatory role of selective miRNAs in insect metamorphosis. a let-7-Complex. In hemimetabolous Blattella germanica, let-7 and miR-100 antagomiR treatment resulted in defective wing formation during metamorphosis [86, 87]. In another hemimetabolous species Locusta migratoria, let-7 suppresses Kr-h1 expression, and let-7 agomiR treatment on penultimate instar nymphs caused partially precocious metamorphosis [88]. In holometabolous Drosophila melanogaster, let-7 and miR-125 target Abrupt and chinmo genes to regulate the morphogenesis of wing and nervous system [78–83]. In holometabolous Bombyx mori, let-7 downregulates E74 and Ftz-f1 genes to control larval–pupal transformation. b miR-2 family. In B. mori, miR-2/13a/13b modulate wing morphogenesis via suppressing the expression of Awd and Fng genes [90]. In B. germanica, miR-2/miR-13a/miR-13b eliminate residual transcripts of Kr-h1 at the final instar nymph to ensure the entry of metamorphosis [91]. c Canonical invertebrate miR-14 regulates molting synchrony and pre-pupation of B. mori by downregulating Spo, Nvd, Shd, EcR and E75 expression [95, 96]. In Chilo suppressalis, miR-14 targets Spo and EcR to control metamorphic development [97]