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Diapause in the pea aphid (Acyrthosiphon pisum) is a slowing but not a cessation of development.

Shingleton AW, Sisk GC, Stern DL - BMC Dev. Biol. (2003)

Bottom Line: We found that early stages of embryogenesis progressed at a temperature-independent rate, characteristic of diapause, whereas later stages of embryogenesis progressed at a temperature-dependent rate.Rather, morphological development progressed slowly but continuously throughout embryogenesis.This suggests that the mechanisms limiting developmental rate during diapause may be the same as those controlling developmental rate at other stages of growth.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544, USA. ashingle@princeton.edu

ABSTRACT

Background: Many insects undergo a period of arrested development, called diapause, to avoid seasonally recurring adverse conditions. Whilst the phenology and endocrinology of insect diapause have been well studied, there has been comparatively little research into the developmental details of diapause. We investigated developmental aspects of diapause in sexually-produced embryos of the pea aphid, Acyrthosiphon pisum.

Results: We found that early stages of embryogenesis progressed at a temperature-independent rate, characteristic of diapause, whereas later stages of embryogenesis progressed at a temperature-dependent rate. However, embryos maintained at very high temperatures during the temperature-independent stage showed severe developmental abnormalities. Under no temperature regime did embryos display a distinct resting stage. Rather, morphological development progressed slowly but continuously throughout embryogenesis.

Conclusion: Diapause in the pea aphid, and perhaps in many other insects, is a temperature-independent slowing but not a cessation of morphological development. This suggests that the mechanisms limiting developmental rate during diapause may be the same as those controlling developmental rate at other stages of growth.

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Examples of developmental defects in embryos maintained at 16°C at day 42. (A) This embryo has red eyes and an egg burster, both characteristic of embryos about to hatch, but the yolk has not been enclosed through dorsal closure. (B) This embryo has red eyes, but is curled at the posterior of the egg, typical of early katatrepsis (see figure 2H). Embryos are orientated as they would be in the egg, with the anterior of the egg to the left. Scale bars are 100 μm long.
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Figure 6: Examples of developmental defects in embryos maintained at 16°C at day 42. (A) This embryo has red eyes and an egg burster, both characteristic of embryos about to hatch, but the yolk has not been enclosed through dorsal closure. (B) This embryo has red eyes, but is curled at the posterior of the egg, typical of early katatrepsis (see figure 2H). Embryos are orientated as they would be in the egg, with the anterior of the egg to the left. Scale bars are 100 μm long.

Mentions: Interpreting these data is, however, problematic, as a high proportion of 16°C embryos showed moderate to severe developmental malformation, making measurement of body and leg length difficult. Malformed embryos were not included in the statistical analysis of growth rates. Figure 6 shows two embryos maintained at 16°C. Typically the embryos showed accelerated development of part but not all of their morphology. In particular many embryos appeared to initiate katatrepsis whilst still under-developed, resulting in embryos with an embryonic cuticle and egg burster, but short or absent limbs. The proportion of malformed embryos increased with time after egg laying. By day 28 10% of sampled embryos showed some abnormality, rising to 90% of embryos sampled on day 49. None of the embryos maintained at 16°C either completed development or hatched.


Diapause in the pea aphid (Acyrthosiphon pisum) is a slowing but not a cessation of development.

Shingleton AW, Sisk GC, Stern DL - BMC Dev. Biol. (2003)

Examples of developmental defects in embryos maintained at 16°C at day 42. (A) This embryo has red eyes and an egg burster, both characteristic of embryos about to hatch, but the yolk has not been enclosed through dorsal closure. (B) This embryo has red eyes, but is curled at the posterior of the egg, typical of early katatrepsis (see figure 2H). Embryos are orientated as they would be in the egg, with the anterior of the egg to the left. Scale bars are 100 μm long.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC184428&req=5

Figure 6: Examples of developmental defects in embryos maintained at 16°C at day 42. (A) This embryo has red eyes and an egg burster, both characteristic of embryos about to hatch, but the yolk has not been enclosed through dorsal closure. (B) This embryo has red eyes, but is curled at the posterior of the egg, typical of early katatrepsis (see figure 2H). Embryos are orientated as they would be in the egg, with the anterior of the egg to the left. Scale bars are 100 μm long.
Mentions: Interpreting these data is, however, problematic, as a high proportion of 16°C embryos showed moderate to severe developmental malformation, making measurement of body and leg length difficult. Malformed embryos were not included in the statistical analysis of growth rates. Figure 6 shows two embryos maintained at 16°C. Typically the embryos showed accelerated development of part but not all of their morphology. In particular many embryos appeared to initiate katatrepsis whilst still under-developed, resulting in embryos with an embryonic cuticle and egg burster, but short or absent limbs. The proportion of malformed embryos increased with time after egg laying. By day 28 10% of sampled embryos showed some abnormality, rising to 90% of embryos sampled on day 49. None of the embryos maintained at 16°C either completed development or hatched.

Bottom Line: We found that early stages of embryogenesis progressed at a temperature-independent rate, characteristic of diapause, whereas later stages of embryogenesis progressed at a temperature-dependent rate.Rather, morphological development progressed slowly but continuously throughout embryogenesis.This suggests that the mechanisms limiting developmental rate during diapause may be the same as those controlling developmental rate at other stages of growth.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544, USA. ashingle@princeton.edu

ABSTRACT

Background: Many insects undergo a period of arrested development, called diapause, to avoid seasonally recurring adverse conditions. Whilst the phenology and endocrinology of insect diapause have been well studied, there has been comparatively little research into the developmental details of diapause. We investigated developmental aspects of diapause in sexually-produced embryos of the pea aphid, Acyrthosiphon pisum.

Results: We found that early stages of embryogenesis progressed at a temperature-independent rate, characteristic of diapause, whereas later stages of embryogenesis progressed at a temperature-dependent rate. However, embryos maintained at very high temperatures during the temperature-independent stage showed severe developmental abnormalities. Under no temperature regime did embryos display a distinct resting stage. Rather, morphological development progressed slowly but continuously throughout embryogenesis.

Conclusion: Diapause in the pea aphid, and perhaps in many other insects, is a temperature-independent slowing but not a cessation of morphological development. This suggests that the mechanisms limiting developmental rate during diapause may be the same as those controlling developmental rate at other stages of growth.

Show MeSH
Related in: MedlinePlus