Vrille is required for larval moulting and metamorphosis of Helicoverpa armigera (Lepidoptera: Noctuidae)

Abstract

Vrille (Vri), a basic leucine zipper transcription factor, plays important roles in insect circadian clock regulation, tracheal development, proliferation, flight and metamorphosis. Here, Helicoverpa armigera was used as a model to investigate the role of Vri in larval moulting and metamorphosis. Sequence analysis results revealed that H. armigera Vri (HaVri) shares a high amino acid identity with other Lepidoptera Vri homologues. Spatial–temporal expression pattern data showed that HaVri expression was highly abundant in larval moulting and metamorphosis stages and was mainly expressed in the midgut and Malpighian tubule during metamorphosis. HaVri knockdown by RNA interference in the fourth‐instar larvae prevented larval moulting, and HaVri knockdown in the fifth‐instar larvae suppressed midgut remodelling and delayed or blocked metamorphosis. Further studies confirmed that 20‐hydroxyecdysone (20E) activated HaVri expression via its heterodimer receptors, ecdysone receptor (EcRB1) and ultraspiracle protein (USP1), whereas methoprene [juvenile hormone analogue (JHA)] promoted HaVri expression via its intracellular receptor methoprene‐tolerant (Met1). However, 20E and JHA can counteract each other in the activation of HaVri expression. Together, the present results suggested that HaVri was involved in larval moulting and metamorphosis and was regulated by 20E and JHA in H. armigera.

The role of clockwork orange in the circadian clock of the cricket Gryllus bimaculatus

“…This result is consistent with our previous findings that the optic lobe is the locus of the circadian clock that controls locomotor rhythms [24], that the compound eye shows circadian rhythms in its sensitivity to light [25], and that the brain shows rhythmic expression of per and tim [26]. It is also expressed at some level in the subesophageal ganglion, but rather constitutively, suggesting that cwo may play a role other than its role in the circadian clock, similar to per and tim in the Drosophila gonads [27], and vri in larval molting and metamorphosis in the moth Helicoverpa armigera [28]. Further studies may reveal additional, non-clock functions of cwo.…”

Molecular Oscillator Affects Susceptibility of Caterpillars to Insecticides: Studies on the Egyptian Cotton Leaf Worm—Spodoptera littoralis (Lepidoptera: Noctuidae)

“…Most of the available data comes from transcriptomic analyses, which indicate the expression of vri and pdp1 in certain tissues and also the rhythmic nature of this expression [ 14 , 15 , 16 ]. As vri and pdp1 genes code for transcription factors, attention is focused not only on their role in the molecular oscillator system itself, but also on the regulation of physiological and developmental processes, both in terms of circadian control and ontogenesis [ 17 , 18 , 19 ]. Most recently, the expression of the cwo gene has also been associated with the lepidopteran response to exogenous factors altering homeostasis [ 20 ].…”