International Journal of Tropical Insect Science

, Volume 2, Issue 4, pp 233–244 | Cite as

Estimation of the Mortality of the Immature Stages of Aedes (Stegomyia) Africanus Theobald in a Tropical Forest in Uganda

  • S. D. K. Sempala


Data on the populations of larval and pupal stages of Aedes africanus, an important sylvan vector of arboviruses, were collected from tree-holes which are its natural breeding sites in forests. Comparable data were also simultaneously collected from bamboo pots stationed in the Zika Forest to simulate the natural breeding sites. Survivorship curves and time-specific life-tables were constructed. It was observed that the immature stages of A. africanus in both tree-holes and bamboo pots suffered very high mortality rates (an average of 91% in tree-holes and 83.2% in bamboo pots). It was further observed that mortality rates varied monthly. The survivorship curves constructed for the immature stages collected on a daily basis tended to show that a large proportion of the mortality rate was confined to the early instar stages, but the survivorship curves based on the combined data for the 2 years indicated constant mortality rates for all the stages. The high mortality rates of the immature stages of A. africanus appear to be attributed to prédation by larvae of Toxorhynchites brevipalpis, with which it shares the same breeding places.

Key Words

Aedes africanus mosquitoes tropical forest Uganda population estimation mortality rate survivorship arboviruses 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Bates M. (1941) Field studies of the anopheline mosquitoes of Albania. Proc. ent. Soc. Wash. 43, 37–58.Google Scholar
  2. Buxton A. P. (1952) Observations on the diurnal behaviour of the redtail monkey Cercopithecus ascanius schmidti in a small forest in Uganda. J. anim. Ecol. 21, 25–58.CrossRefGoogle Scholar
  3. Corbet P. S. (1964) Observations on mosquitoes ovipositing in small containers in Zika Forest, Uganda. J. anim. Ecol. 33, 141–164.CrossRefGoogle Scholar
  4. Haddow A. J. (1964) Observations on the biting habits of mosquitoes in the forest canopy at Zika, Uganda, with special reference to the crepuscular periods. Bull. ent. Res. 55, 589–608.CrossRefGoogle Scholar
  5. Haddow A. J. (1968) The natural history of yellow fever in Africa. Proc. R. Soc. Edinb. 70, 191–227.Google Scholar
  6. Kirva B. G.,, Mukwaya L. G. and Sempala S. D. K. (1977) A yellow fever epizootic in Zika forest, Uganda, during 1972: part I. Virus isolation and sentinel monkeys. Trans. R. Soc. trop. Med. Hyg. 71, 254–260.CrossRefGoogle Scholar
  7. Lakhani K. H. and Service M. W. (1974) Estimated mortalities of the immature stages of Aedes cantans (Diptera, Culicidae) in a natural habitat. Bull. ent. Res. 64, 265–276.CrossRefGoogle Scholar
  8. Lounibos L. P. (1979) Temporal and spatial distribution, growth and predatory behaviour of Toxorhynchites bre-vipalpis (Diptera: Culicidae) on the Kenya coast. J. anim. Ecol. 48, 213–236.CrossRefGoogle Scholar
  9. Reisen W. K. and Siddiqui T. F. (1979) Horizontal and vertical estimates of immature survivorship for Culex tri-teanìorhynchus (Diptera, Culicidae) in Pakistan. J. med. Ent. 16, 207–218.CrossRefGoogle Scholar
  10. Sempala S. D. K. (1971) Some aspects of the biology of tree-hole breeding mosquitoes with special reference to Aedes (Stegomyia) africanus and Aedes Stegomyia) apicoargenteus (Diptera, Culicidae). M.Sc. thesis. University of East Africa.Google Scholar
  11. Sempala S. D. K. (1976) Studies on the bionomics and ecology of Aedes (Steyomyia) africanus (Diptera, Culicidae) in a tropical forest in Uganda. Ph.D. thesis, University of Nairobi, Kenya.Google Scholar
  12. Sempala S. D. K. (1981) Interactions between immature Aedes africanus (Theobald) and larvae of two predatory species of Toxorhynchites (Diptera, Culicidae) in Zika forest, Uganda. Bull. ent. Res. In press.Google Scholar
  13. Service M W. (1973) Mortalities of the larvae of the Anopheles gambiae Giles complex and detection of predators by the precipitin test. Bull ent. Res. 62, 359–369.CrossRefGoogle Scholar
  14. Service M. W. (1977) Mortalities of the immature stages of species B of the Anopheles gambiae in Kenya: comparison between rice fields and temporary pools, identification of predators, and effects of insecticidal spraying. J. med. Ent. 13, 535–544.CrossRefGoogle Scholar
  15. Slobodkin L. B. (1962) Growth and Regulation of Animal Populations. Holt, Rinehart & Winston, New York.Google Scholar
  16. Southwood T. R. (1966) Ecological Methods. Methuen, London.Google Scholar
  17. Southwood T. R.,, Murdie G., Yasuno M., Tonn R. J. and Reader P. M. (1972) Studies on the life budget of Aedes aegypli in Wat Samphaya, Bangkok, Thailand. Bull. Wld Hit h Org. 46, 211–226.Google Scholar
  18. Varley G. C. and Gradwell G. R. (1960) Key factors in population studies. J. anim. Ecol. 29, 399–401.CrossRefGoogle Scholar
  19. Varley G. C., Gradwell G. R. and Hassell M. P. (1974) Insect Population Ecology: An Analytical Approach. University of California Press, Berkeley.Google Scholar
  20. Woodall J. P. (1964) The viruses isolated from arthropods at the East African Virus Research Institute in 26 years ending December, 1963. Proc. E. Afr. Acad. 2, 141–146.Google Scholar

Copyright information

© ICIPE 1982

Authors and Affiliations

  • S. D. K. Sempala
    • 1
  1. 1.Department of Entomology and Vertebrate ZoologyUganda Virus Research InstituteEntebbeUganda

Personalised recommendations