Studies of the mortality rate of Culicoides imicola in Morocco

Conference paper


Daily mortality rates of female Culicoides imicola were found for eight sites in Morocco in 1994 and for six sites in 1995. The mortality rates were found by operating Pirbright-type light traps for a number of consecutive nights in late summer or autumn and finding the parous rate assuming a feeding interval of 3 to 5 days. The mortality rates were calculated according to established methods. In Morocco the daily mortality rates were found to vary from about 5% per day (Arbaoua, 1994, 1995 and Sidi Moussa 1995) up to 20–25% per day (Berkane, Marrakech, Tangier). In general, estimates of daily mortality rate were consistent between the two years of study. Among sites, daily mortality rate was significantly correlated with the average night-time minimum wind speed but not mean or maximum night-time wind speeds, or with temperature, humidity or saturation deficit. The observed mortality rates suggest that at Arbaoua, were 1 000 flies to become infected with African horse sickness virus, at least 330 would live long enough to take 3 or more infective blood meals on hosts. At Berkane, the survival rate per 1 000 is less than 10. In general, the pattern observed for daily mortality rate, combined with the relative population sizes of C. imicola in Morocco, agree well with the observed distribution of African horse sickness in the country during the 1989–1991 epizootic.


Wind Speed Blood Meal Parous Rate High Wind Speed Saturation Deficit 
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  1. 1.
    Anonymous (1992) La peste équine au Maroc. Epizooties de 1989, 1990 et 1991. Données epidemiologiques et Strategie de lutte. Report of the Direction de l’Elevage, Ministére de l’Agriculture et de la Reforme Agraire, Rabat, MoroccGoogle Scholar
  2. 2.
    Baylis M, Bouayoune H, Touti J, El Hasnaoui H (1998) Use of climatic data and satellite imagery to model the abundance of Culicoides imicola Kieffer, the vector of African horse sickness virus, in Morocco. Med Vet Entomol 12Google Scholar
  3. 3.
    Baylis M, El Hasnaoui H, Bouayoune H, Touti J, Mellor PS (1997) The spatial and seasonal distribution of African horse sickness and its potential Culicoides vectors in Morocco. Med Vet Entomol 11: 203–212PubMedCrossRefGoogle Scholar
  4. 4.
    Birley MH, Boorman, JPT (1982) Estimating the survival and biting rates of haematophagous insects, with particular reference to the Culicoides obsoletus group ( Diptera, Ceratopogonidae) in southern England. J Anim Ecol 51: 135–148CrossRefGoogle Scholar
  5. 5.
    Birley MH, Rajagopalan PK (1981) Estimation of the survival and biting rates of Culex quinquefasciatus ( Diptera: Culicidae). J Med Entomol 18: 181–186PubMedGoogle Scholar
  6. 6.
    Braverman Y, Linley JR, Marcus R, Frish K (1985) Seasonal survival and expectation of infective life of Culicoides spp. (Diptera: Ceratopogonidae) in Israel, with implications for bluetongue virus transmission and a comparison of the parous rate in C. imicola from Israel and Zimbabwe. J Med Entomol 22: 476–484PubMedGoogle Scholar
  7. 7.
    Dyce AL (1969) The recognition of nulliparous and parous Culicoides (Diptera: Ceratopogonidae) without dissection. J Aust Entomol Soc 8: 11–15CrossRefGoogle Scholar
  8. 8.
    Dye C (1990) Epidemiological significance of vector-parasite interactions. Parasitology 101: 409–415PubMedCrossRefGoogle Scholar
  9. 9.
    Mullens BA (1985) Sampling bias and the problem of age survivorship determination in Culicoides. In: Bluetongue and related orbiviruses. Alan R Liss, New York, pp 207–211 (Progress in Clinical and Biological Research, vol 178)Google Scholar
  10. 10.
    Sellers RF (1980) Weather, host and vector — their interplay in the spread of insect-borne animal virus diseases. J Hyg 85: 65–102CrossRefGoogle Scholar
  11. 11.
    Sellers RF, Pedgley DE, Tucker MR (1978) Possible windborne spread of bluetongue to Portugal, June—July 1956. J Hyg 81: 189–196CrossRefGoogle Scholar
  12. 12.
    Walker AR (1977) Adult lifespan and reproductive status of Culicoides species (Diptera: Ceratopogonidae) in Kenya, with reference to virus transmission. Bull Entomol Res 67: 205–215CrossRefGoogle Scholar
  13. 13.
    Wellby M, Baylis M, Rawlings P, Mellor PS (1996) Effect of temperature on survival and rate of virogenesis of African horse sickness virus in Culicoides variipennis sonorensis ( Diptera: Ceratopogonidae) and its significance in relation to the epidemiology of the disease. Bull Entomol Res 86: 715–720CrossRefGoogle Scholar
  14. 14.
    Work TM, Mullens BA, Jessup DA (1991) Estimation of survival and gonotrophic cycle length of Culicoides variipennis (Diptera: Ceratopogonidae) in California. J Am Mosq Control Assoc 7: 242–249PubMedGoogle Scholar

Copyright information

© Springer-Verlag/Wien 1998

Authors and Affiliations

  1. 1.Institute for Animal HealthPirbrightUK
  2. 2.Laboratoire Régional d’Analyses et de Recherches Vétérinaires d’AgadirMorocco
  3. 3.Laboratoire Régional d’Analyses et de Recherches Vétérinaires de FèsMorocco
  4. 4.Laboratoire Régional d’Analyses et de Recherches Vétérinaires d’OujdaMorocco
  5. 5.Laboratoire Régional d’Analyses et de Recherches Vétérinaires de MarrakechMorocco
  6. 6.Laboratoire Régional d’Analyses et de Recherches Vétérinaires de CasablancaMorocco
  7. 7.Institute for Animal HealthPirbright, SurreyUK

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