Myosuppressin is involved in the regulation of pupal diapause in the cabbage army moth Mamestra brassicae

Nobuto Yamada,Hiroshi Kataoka,Akira Mizoguchi

doi:10.1038/srep41651

Nobuto Yamada, Hiroshi Kataoka + Show 1 more

Open Access

https://doi.org/10.1038/srep41651

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Abstract

Diapause, a programmed developmental arrest, is common in insects, enabling them to survive adverse seasons. It is well established that pupal diapause is regulated by ecdysteroids secreted by the prothoracic glands (PGs), with cessation of ecdysteroid secretion after pupal ecdysis leading to pupal diapause. A major factor regulating the gland activity is prothoracicotropic hormone (PTTH) secreted from the brain. In our previous study, we demonstrated that the cessation of PTTH release after pupal ecdysis resulted in the inactivation of the PGs, leading to pupal diapause in the cabbage army moth Mamestra brassicae. Here we show that a neuropeptide myosuppressin also contributes to the inactivation of PGs at the initiation of diapause. Myosuppressin suppresses PTTH-stimulated activation of the PGs in vitro. Concentrations of myosuppressin in the hemolymph after pupal ecdysis are higher in diapause pupae than in nondiapause pupae.

Highlights

Diapause, a programmed developmental arrest, is common in insects, enabling them to survive adverse seasons
We previously demonstrated that the cessation of prothoracicotropic hormone (PTTH) secretion after pupal ecdysis was critical for the initiation of diapause
These results suggested that the prothoracic glands (PGs) of diapause pupae rapidly lose their responsiveness to PTTH soon after pupation

Summary

Introduction

A programmed developmental arrest, is common in insects, enabling them to survive adverse seasons. There has been a long-standing belief that the cessation of PTTH secretion leads to the initiation of diapause since Carroll Williams proposed this hypothesis in 1952 based on his study using diapause pupae of the giant silk moth Hyalophora cecropia[11] This hypothesis was verified only recently by demonstrating the absence of PTTH in the hemolymph of diapause pupae in the cabbage army moth Mamestra brassicae[12], indirect evidence for the decline of PTTH secretory activity of the brain in diapausing pupae had previously been presented in some insects[3]. This peptide is considered to regulate the timing of metamorphosis by suppressing the PG activity All these neuropeptides are suggested to play roles in the regulation of PG activity during larval-pupal development in B. mori, their function as developmental regulators has not yet been fully established, due to a lack of demonstrations of their in vivo actions and of information about their hemolymph titers, and to a paucity of studies in other insects and at other developmental stages. We show that BMS is involved in the regulation of PG activity in M. brassicae, playing an important role in the initiation and maintenance of pupal diapause

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