Mutation of the clock gene timeless disturbs diapause induction and adult emergence rhythm in Helicoverpa armigera

Abstract

Background Circadian rhythms are physical and behavioral changes that follow the 24‐h cycle of Earth's light and temperature and are regulated by clock genes. Timeless (Tim) has been identified as a canonical clock gene in some insects, however, its functions have been little studied in lepidopteran pests. Results To investigate Tim (HaTim) gene function in Helicoverpa armigera, an important lepidopteran pest, we obtained the HaTim mutant using the CRISPR/Cas9 gene editing system. Our results showed that the transcript levels of HaTim rhythmically peaked at night in heads of the wild larvae and adult, and the diel expression of HaTim was sensitive to photoperiod and temperature. The expression rhythms of other clock genes, such as HaPer, HaCry1, HaCry2 and HaCwo, were disturbed in the HaTim mutant larvae, as that stage is a sensitivity period for diapause induction. Fifth‐instar wild‐type larvae could be induced to pupate in diapause under a short‐day photoperiod and low temperature, however, fifth‐instar HaTim mutant larvae could not be induced under the same conditions. In addition, the emergence of wild‐type adults peaked early at night, but the rhythm was disturbed in the HaTim mutant with arrhythmic expression of some clock genes, such as HaPer, HaCry1 and HaCwo in adults. Conclusion Our results suggest that the clock gene Tim is involved in diapause induction and adult emergence in H. armigera, and is a potential target gene for controlling pest. © 2023 Society of Chemical Industry.

Knockout ofcryptochrome 1disrupts circadian rhythm and photoperiodic diapause induction in the silkworm,Bombyx mori

“…In the present study, the cry1 gene exhibited rhythmic expression in the larval head of B. mori, peaking at early photophase. This expression patters aligns with findings in the adult brain and antennae of the African cotton leafworm, Spodoptera littoralis (Merlin et al, 2007), and in the larval and adult head of the cotton bollworm, Helicoverpa armigera (Yan et al, 2013;Liu et al, 2023). Our results are also consistent with a previous study involving B. mori embryos (Qiu et al, 2023a).…”

“…The timing of hatching and adult eclosion in lepidopterans is under circadian clock control, as verified by clock gene knockout experiments in some species (Merlin et al, 2013;Brady et al, 2021;Chen et al, 2023;Liu et al, 2023;Wang et al, 2023). Previous studies in B. mori reported the loss of these rhythms in per and tim knockout strains (Ikeda et al, 2019;Nartey et al, 2021).…”