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Hydrobiologia

, Volume 36, Issue 1, pp 33–52 | Cite as

A population study on larvae of the damselfly Pyrrhosoma nymphula (Sulzer) (Odonata: Zygoptera)

  • J. H. Lawton
Article

Summary

  1. 1.

    Data on population density, mortality rates and seasonal changes in distribution in larvae of the damselflyPyrrhosoma nymphula (Sulzer) (Odonata: Zygoptera) are described. Field work was carried out between July 1966 and July 1968 in a small weedy pond near to Durham City.

     
  2. 2.

    Samples were taken using a standard net sweep, and converted to numbers per m2 using a conversion factor.

     
  3. 3.

    Larvae made pronounced movements during development, one consequence of which was the virtual complete separation of senior and junior age-classes into different areas of the pond throughout development. This may have been important in preventing predation by large larvae on smaller individuals.

     
  4. 4.

    Mortality rates were constant within year-classes but varied between year-classes, being 99.5, 78 and between 60 and 70 percent per annum in the 1965, 1966 and 1967 year-classes respectively.

     
  5. 5.

    Larval population densities varied markedly between year-classes. Thus, there were approximately 340 and 110 newly hatched larvae per m2 in July 1966 and 1967 respectively, and 2 and 23 final instars per m2 prior to emergence in May 1967 and 1968 respectively.

     
  6. 6.

    An independent check on the population data was possible at emergence. Complete collections of exuvia yielded estimates of the number of larvae emerging from the pond that were 24 percent more in 1967 and 34 percent less in 1968 than the calculated number of larvae present prior to emergence.

     

Keywords

Population Density Avant Conversion Factor Complete Separation Small Individual 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Résumé

  1. 1.

    Des données sur la densité de la population, sur les taux de mortalité et sur les changements de saison dans la distribution des larves de la demoisellePyrrhosoma nymphula (Sulzer) (Odonata: Zygoptera) sont décrites. On a étudié les populations d'un petit étang plein de mauvaises herbes dans les environs de Durham City entre juillet 1966 et juillet 1968.

     
  2. 2.

    On a pris des échantillons par moyen d'un filet, puis on a converti le nombre d'échantillons en numéros par mètre carré, en utilisant un diviseur de conversion.

     
  3. 3.

    Les larves ont fait des mouvements marqués pendant leur développement, et par conséquence les plus grandes larves et les juniors se sont séparés presque totalement, s'emparant des endroits différents de l'étang pour la période entière. Il se peut que cette séparation a empêché que les plus petites larves soient attaquées par les plus grandes.

     
  4. 4.

    Les taux de mortalité étaient constants dans les classes de chaque année, mais ils ont varié entre ces classes, étant 99.5, 78 et environ 60–70 pour cent par an dans les classes de 1965, 1966 et 1967 respectivement.

     
  5. 5.

    Les densités des populations de larves sont beaucoup variés entres les classes de chaque année. Ainsi, il y avait environ 340 et 110 larves récemment écloses par mètre carré en juillet 1966 et en juillet 1967; et 2 et 23 instars finals par mètre carré avant leur émergence en mai 1967 et mai 1968.

     
  6. 6.

    On a pu vérifier indépendamment les données sur la population au moment où les instars se sont apparus. De ces collections complètes d'exuvia, on a tiré des calculs sur le nombre de larves sortant de l'étang; ce nombre était 24% plus en 1967 et 34% moins en 1968 du nombre calculé de larves qui étaient présentes avant l'émergence.

     

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References

  1. Ball, R. C. & Hayne, D. W. - 1952 - Effects of the fish population on the fish-food organisms of a lake.Ecology 33: 41–48.Google Scholar
  2. Berg, K. & Petersen, I. C. - 1956 - Studies on the humic, acid Lake Gribsø.Folia limnol. Scand. 8: 273 pp.Google Scholar
  3. Clark, L. R., Geier, P. W., Hughes, R. D. & Morris, R. F. - 1967 - The Ecology of Insect Populations in theory and practice. Methuen, London.Google Scholar
  4. Corbet, P. S. - 1952 - An adult population study ofPyrrhosoma nymphula (Sulzer): (Odonata: Coenagrionidae).J. Anim. Ecol. 21: 206–222.Google Scholar
  5. Corbet, P. S. - 1957a - The life-history of the Emperor Dragonfly,Anax imperator Leach (Odonata: Aeshnidae).J. Anim. Ecol. 26: 1–69.Google Scholar
  6. Corbet, P. S. - 1957b - The life-histories of two spring species of dragonfly (Odonata: Zygoptera).Ent. Gaz., Lond. 8: 79–89.Google Scholar
  7. Corbet, P. S. - 1962 - A biology of dragonflies. Witherby, London.Google Scholar
  8. Dineen, C. F. - 1953 - An ecological study of a Minnesota pond.Amer. Midl. Nat. 50: 349–376.Google Scholar
  9. Hassel, M. P. - 1966 - Evaluation of parasite or predator responses.J. Anim. Ecol. 35: 65–75.Google Scholar
  10. Kormondy, E. J. - 1959 - The systematics ofTetragoneuria, based on ecological life history and morphological evidence (Odonata: Corduliidae).Misc. Publ. Mus. Zool. Univ. Mich. 107: 1–79.Google Scholar
  11. Lawton, J. H. - 1969 - Studies on the ecological energetics of damselfly larvae (Odonata: Zygoptera). Ph. D. thesis, University of Durham.Google Scholar
  12. Lucas, W. J. - 1930 - The aquatic (naiad) stage of the British dragonflies (Paraneuroptera).London, Ray Soc. Publ. 117.Google Scholar
  13. Macan, T. T. - 1964 - The Odonata of a moorland fishpond.Int. Revue ges. Hydrobiol. Hydrogr. 49: 325–360.Google Scholar
  14. Macan, T. T. - 1966 - The influence of predation on the fauna of a moorland fishpond.Arch. Hydrobiol. 61: 432–452.Google Scholar
  15. Macan, T. T., McCormack, J. C. & Maudsley, R. - 1966–67 - An experiment with trout in a moorland fishpond.Salmon and Trout Magazine, Sept. 1966 and January 1967.Google Scholar
  16. Mann, K. H. - 1964 - The pattern of energy flow in the fish and invertebrate fauna of the River Thames.Verh. Int. Verein. Limnol. 15: 485–495.Google Scholar
  17. Moore, N. W. - 1953 - Population density in adult dragonflies (Odonata: Anisoptera).J. Anim. 22: 344–359.Google Scholar
  18. Moore, N. W. - 1964 - Intra- and interspecific competition among dragonflies (Odonata): an account of observations and field experiments on population density control in Dorset, 1954–1960.Anim. Ecol. 33: 49–71.Google Scholar
  19. Snedecor, G. W. & Cochran, W. G. - 1967 - Statistical Methods. 6th Ed. Iowa State Univ. Press.Google Scholar

Copyright information

© Dr. W. Junk n.v. Publishers 1970

Authors and Affiliations

  • J. H. Lawton
    • 1
  1. 1.Department of ZoologyUniversity of DurhamDurham CityEngland

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