Cell death and wing reduction during the metamorphosis of sex-specific flightless morphs in winter geometrid moths.

Winter geometrid moths show striking sexual dimorphism by having female-specific flightless morphs. The evolutionary grades of wing reduction in winter geometrid moths vary and range from having short wings, vestigial wings, to being wingless. Although the ontogenetic processes underlying the development of the wingless or short-wing morphs in Lepidoptera has been well studied, the mechanisms underlying the development of vestigial wing morphs in winter geometrid moths during metamorphosis are poorly understood.

Early cellular development induced by ecdysteroid in sex-specific wing degeneration of the wingless female winter moth.

The winter moth, Nyssiodes lefuarius, exhibits striking sexual dimorphism in wing form; males have functional wings of normal size, whereas females lack wings. We previously found that the steroid hormone 20-hydroxyecdysone (20E) triggered massive programmed cell death (PCD) only in the female pupal wing epithelium; however, when and how early sexual trait development of the pupal wings is initiated during pupal-adult metamorphosis remains obscure. To clarify the detailed morphological changes and mechanisms underlying early sexual trait development and cell death, we examined the effects of 20E on early ultrastructural and histological changes in the pupal wing epithelium of both sexes.

Discovery of wing imaginal discs in the penultimate instar of the lacewing Mallada desjardinsi (Insecta: Neuroptera: Chrysopidae) with histological notes on postembryonic imaginal disc development.

Holometabolous insects are alternatively named "Endopterygota" because, in the larvae of many taxa, the wing primordia in the lateral regions of the meso- and metathoracic segments form more or less invaginated structures called wing imaginal discs. Holometabolous insects exhibit differential developmental timing of the wing during ontogeny. The condition in which wing growth is deferred until the end of larval life has been considered ancestral, whereas early disc formation has been recognized as the derived condition.

Morphological and histological examination of short-wing formation in the winter moth Protalcis concinnata (Insecta: Lepidoptera, Geometridae).

Winter geometrid moths exhibit sexual dimorphism in wing length and female-specific flightlessness. Female-specific flightlessness in insects is an interesting phenomenon in terms of sexual dimorphism and reproductive biology. In the winter geometrid moth, Protalcis concinnata (Wileman), adult females have short wings and adult males have fully developed wings.

Distribution of Dall's Porpoise, Phocoenoides dalli, in the North Pacific and Bering Sea, Based on T/S Oshoro Maru 2012 Summer Cruise Data.

Dall's porpoise (Phocoenoides dalli) is a small toothed cetacean, widely inhabiting the North Pacific Ocean and adjacent seas, between about 30 and 62°N; however, only limited studies of its ecology have been made in nearshore areas. A cetacean sighting survey lasting 60 days was conducted during the 2012 summer cruise of the T/S Oshoro Maru (Hokkaido University, Japan) in the North Pacific Ocean and Bering Sea. Based on this data, the distribution of Dall's porpoises and the factors controlling it in the pelagic habitat were investigated.

Ecdysteroid-induced programmed cell death is essential for sex-specific wing degeneration of the wingless-female winter moth.

The winter moth, Nyssiodes lefuarius, has a unique life history in that adults appear during early spring after a long pupal diapause from summer to winter. The moth exhibits striking sexual dimorphism in wing form; males have functional wings of normal size, whereas females lack wings. We previously found that cell death of the pupal epithelium of females appears to display condensed chromatin within phagocytes.

In vitro effects of juvenile hormone analog on wing disc morphogenesis under ecdysteroid treatment in the female-wingless bagworm moth Eumeta variegata (Insecta: Lepidoptera, Psychidae).

Female adults of the bagworm moth, Eumeta variegata, lack wings completely, whereas male adults of this species have functional wings. We previously found that ecdysteroid induces apoptotic events in the female wing rudiment of E. variegata in vitro, whereas the male wing discs cultured with 20-hydroxyecdysone (20E) underwent apolysis and then cell differentiation.

Feminization of genetic males by a symbiotic bacterium in a butterfly, Eurema hecabe (Lepidoptera: Pieridae).

Wolbachia are symbiotic bacteria found in many arthropods and filarian nematodes. They often manipulate the reproduction of host arthropods. In the present study, female-biased sex-ratio distortion in the butterfly Eurema hecabe was investigated.