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Dryad

A basic helix-loop-helix/Per-Arnt-Sim transcription factor Taiman is essential for metamorphosis in Henosepilachna vigintioctomaculata

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Nov 11, 2025 version files 85.76 KB

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Abstract

Insect Taiman (Tai) is a basic helix-loop-helix (bHLH)/Per-Arnt-Sim (PAS) transcription factor that plays a role in juvenile hormone (JH) signaling during the larval stage in various insect species, as well as in 20-hydroxyecdysone (20E) signaling during the oogenesis of Drosophila melanogaster. It forms a heterodimer with another bHLH-PAS transcription factor Methoprene-tolerant (Met) mediating JH signaling, and acts as a steroid receptor coactivator of the functional 20E receptor heterodimer, Ecdysone receptor (EcR) and Ultraspiracle (USP). However, whether Tai plays the dual functions in other insects deserves further exploration. In this study, we determined the role of Tai in Henosepilachna vigintioctomaculata, a Coleopteran potato pest mainly distributed in northern China. HvTai mRNA levels were higher just before and right after the ecdysis within each larval instars and at early and late stages of prepupae than those in the intermediate days. RNA interference (RNAi)-aided knockdown of Tai at the second, penultimate, and final larval instar stages caused 100% mortalities 9, 11, and 10 days post dsRNA administration. All Tai RNAi larvae failed to complete molting, they were wrapped in the old larval exuviae, gradually darkened and shriveled, and ultimately died. The Tai-depleted larvae did not complete gut clearing, the larval guts contained food residues. Moreover, knockdown of *Tai *disrupted both JH and 20E pathway genes. Our findings demonstrated that Tai was necessary for metamorphosis in H. vigintioctomaculata. The findings also imply that H. vigintioctomaculata is an ideal model for further exploration of how Tai contributes specifically to hormone signaling.