Silkworm strains that can be clearly destined towards either embryonic diapause or direct development by adjusting a single ambient parameter during the preceding generation

2014 ◽  
Vol 17 (4) ◽  
pp. 396-399 ◽  
Author(s):  
Yuichi Egi ◽  
Shion Akitomo ◽  
Tsuguru Fujii ◽  
Yutaka Banno ◽  
Katsuhiko Sakamoto
Keyword(s):  
Direct Development ◽  
Embryonic Diapause

scholarly journals The formation of a hatching line in the serosal cuticle confers multifaceted adaptive functions on the eggshell of a cicada

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Minoru Moriyama ◽  
Kouji Yasuyama ◽  
Hideharu Numata
Keyword(s):  
Protective Role ◽  
Terminal Phase ◽  
Embryonic Diapause ◽  
Insect Eggs ◽  
Ridge Structure ◽  
Conflicting Demands ◽  
Partial Degradation ◽  
Egg Period ◽  
Eggshell Structure

AbstractInsect eggshells must meet various demands of developing embryos. These demands sometimes conflict with each other; therefore, there are tradeoffs between eggshell properties, such as robustness and permeability. To meet these conflicting demands, particular eggshell structures have evolved in diverse insect species. Here, we report a rare eggshell structure found in the eggshell of a cicada, Cryptotympana facialis. This species has a prolonged egg period with embryonic diapause and a trait of humidity-inducible hatching, which would impose severe demands on the eggshell. We found that in eggs of this species, unlike many other insect eggs, a dedicated cleavage site, known as a hatching line, was formed not in the chorion but in the serosal cuticle. The hatching line was composed of a fine furrow accompanied by ridges on both sides. This furrow-ridge structure formed in the terminal phase of embryogenesis through the partial degradation of an initially thick and nearly flat cuticle layer. We showed that the permeability of the eggshell was low in the diapause stage, when the cuticle was thick, and increased with degradation of the serosal cuticle. We also demonstrated that the force required to cleave the eggshell was reduced after the formation of the hatching line. These results suggest that the establishment of the hatching line on the serosal cuticle enables flexible modification of eggshell properties during embryogenesis, and we predict that it is an adaptation to maximize the protective role of the shell during the long egg period while reducing the barrier to emerging nymphs at the time of hatching.

The Reproductive Biology of Ophiacantha Bidentata (Echinodermata: Ophiuroidea) From The Rockall Trough

1982 ◽  
Vol 62 (1) ◽  
pp. 45-55 ◽  
Author(s):  
P. A. Tyler ◽  
J. D. Gage
Keyword(s):  
Reproductive Biology ◽  
Deep Water ◽  
Larval Stage ◽  
North Pacific ◽  
Deep Sea ◽  
Direct Development ◽  
The Arctic ◽  
Shallow Waters ◽  
Arctic Seas ◽  
Rockall Trough

INTRODUCTIONOphiacantha bidentata (Retzius) is a widespread arctic-boreal ophiuroid with a circumpolar distribution in the shallow waters of the Arctic seas and penetrating into the deep sea of the.North Atlantic and North Pacific (Mortensen, 1927, 1933a; D'yakonov, 1954). Early observations of this species were confined to defining zoogeo-graphical and taxonomic criteria including the separation of deep water specimens as the variety fraterna (Farran, 1912; Grieg, 1921; Mortensen, 1933a). Mortensen (1910) and Thorson (1936, pp. 18–26) noted the large eggs (o.8 mm diameter) in specimens from Greenland and Thorson (1936) proposed that this species had ‘big eggs rich in yolk, shed directly into the sea. Much reduced larval stage or direct development’. This evidence is supported by observations of O. bidentata from the White and Barents Seas (Semenova, Mileikovsky & Nesis, 1964; Kaufman, 1974)..

Reproductive Ecology of The Allied Rock-wallaby, Petrogale assimilis.

1996 ◽  
Vol 19 (2) ◽  
pp. 209
Author(s):  
R. Delaney
Keyword(s):  
Life History ◽  
Sex Ratio ◽  
Sexual Maturity ◽  
Post Partum ◽  
Reproductive Ecology ◽  
Oestrous Cycle ◽  
Embryonic Diapause ◽  
Minimum Age

Petrogale assimilis has a typical life history and reproductive ecology for a macropodid of its size. Both sexes are capable of reproducing continuously; gestation is about the same length as the oestrous cycle (approximately one month); a single young is born and, a post-partum oestrus and embryonic diapause probably occurs. The sex ratio of young is unbiased. Pouch young remain permanently attached to the teat until 110 - 143 days (n=11). Permanent exit from the pouch occurs at 180 - 231 days (mean=201 days, n=25), and weaning occurs between 267 - 387 days (n=5). Sexual maturity occurs at a minimum age of 17.5 months in females and 23 months in males.

PHOTOPERIODIC CONTROL OF DEVELOPMENT AND PHENOTYPE IN A SUBARCTIC POPULATION OF PIERIS OCCIDENTALIS (LEPIDOPTERA: PIERIDAE)

1975 ◽  
Vol 107 (7) ◽  
pp. 775-779 ◽  
Author(s):  
Arthur M. Shapiro
Keyword(s):  
Sierra Nevada ◽  
Continuous Light ◽  
Direct Development ◽  
Source Population ◽  
Photoperiodic Control ◽  
Temperature Regimes

AbstractPieris occidentalis nelsoni W. H. Edwards from Fairbanks, Alaska, was reared under a variety of photoperiod–temperature regimes. The source population is presumably univoltine and monophenic, with a phenotype resembling the vernal one produced by multivoltine, diphenic P. o. occidentalis Reakirt in Colorado and California. Photoperiods of 10 or 15 h produced 100% diapause pupae at 15 °C and circa 65% at 25 °C. Under continuous light 22% diapaused at 15 °C and < 1% at 25 °C. About 20% of non-diapause pupae produced adults resembling the estival phenotype of P. o. occidentalis, which is unknown in wild P. o. nelsoni. Although nelsoni is more likely to diapause than the nominate subspecies from the Sierra Nevada, its potential for direct development and polyphenism is interpreted as evidence that it is derived from a multivoltine ancestor.

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