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Capacity of discontinuous egg development and its importance for the geographic distribution of the warm water stenotherm, Dinocras cephalotes (Insecta: Plecoptera: Perlidae)
Aspects of the egg biology of the perlid stonefly, Dinocras cephalotes (Curtis), were studied experimentally. Development under constant laboratory conditions did not differ from development under variable field conditions. Exposure to 4°C, the lower threshold temperature for egg development, caused...
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Published in: | Annales de limnologie 1996-01, Vol.32 (3), p.147-160 |
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Format: | Article |
Language: | English |
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Summary: | Aspects of the egg biology of the perlid stonefly, Dinocras cephalotes (Curtis), were studied experimentally. Development under constant laboratory conditions did not differ from development under variable field conditions. Exposure to 4°C, the lower threshold temperature for egg development, caused abrupt interruptions of embryonic development. Development was resumed after return to favourable temperatures, with an approximate two-week-delay. Up to six interruptions of egg development did not negatively affect hatching success, regardless of developmental stage at which disturbances occurred. However, the older embryos grew, the more rapidly development was resumed after a cold disturbance; embryos from fully developed eggs hatched even at 4°C, although this is too cold to support larval growth. While eggs at 4°C remain dormant and vital for long periods of time, eggs exposed to suboptimal temperatures (10°C) remain only temporarily dormant and eventually develop and hatch. D. cephalotes is assumed to satisfy its high thermal demand for egg development under harsh conditions, for example in arctic Scandinavia, by opportunistically using summer warmth and spreading embryogenesis over more than one year. I suggest that high cue temperatures required to initiate egg development in Scandinavian populations are adaptive and ensure that larvae in the Arctic hatch under favourable seasonal conditions.
Certains aspects de la biologie de l'œuf du Plécoptère Perlidae, Dinocras cephalotes (Curtis) ont été étudiés expérimentalement. Le développement dans des conditions constantes de laboratoire ne diffère pas de celui sous des conditions variables en milieu naturel. Une exposition à 4°C, température minimale requise pour le développement de l'œuf, entraîne de brusques interruptions du développement embryonnaire. Le retour à une température favorable entraîne une reprise du développement dans un délai d'environ 2 semaines. Jusqu'à 6 interruptions du développement de l'œuf n'empêchent pas le succès de l'éclosion, indépendamment de l'état de développement auquel se produisent les perturbations. Cependant, plus les embryons sont âgés, plus le développement reprend rapidement après une baisse de température ; des embryons issus d'œufs entièrement développés éclosent même à 4°C bien que cette température soit trop basse pour permettre la croissance larvaire. Alors que des œufs à 4°C peuvent rester en dormance pendant de longues périodes, des œufs exposés à des température |
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ISSN: | 0003-4088 2100-000X |
DOI: | 10.1051/limn/1996014 |