International Journal of Modern Biological Research
ISSN: 2053-180X
Vol. 4(3), pp. 16-24, March 2016
doi.org/10.33500/ijmbr.2016.4.003



Physical factors associated with Anopheles and Culex mosquitoes’ survival in captivity in Yola, Nigeria

Umaru, N. F.1* and Akogun, O. B.2

1Directorate of Research, National Institute for Policy and Strategic Studies, Kuru Jos, Nigeria.
2Department of Zoology, Moddibo Adama University of Technology, Yola.

*To whom correspondence should be addressed. E-mail: umarnuhu2003@yahoo.com.

Received 20 January, 2016; Received in revised form 24 February, 2016; Accepted 01 March, 2016.

Abstract


Keywords:
Anopheles, Culex, Temperature, Relative humidity, Water depth.


A study on the physical factors associated with Anopheles and Culex Mosquitoes’ survival in captivity in Yola, Nigeria was carried with a view to identifying optimal physical conditions for their survival in captivity; in order to raise high quality mosquitoes colonies in the laboratory for scientific studies in the areas such as insecticides and larvicides resistance. Indoor and outdoor bite collections of gravid Anopheles and Culex mosquitoes were made using plastic aspirator from residential areas within Jimeta-Yola metropolis for three years at intervals of seven days in the months of March to May and August to October. Standard morphological keys and Polymerase Chain Reaction (PCR) identification methods were used to classify them. Factors associated with their survival in captivity namely temperature, percentage relative humidity and water depths were determined on daily basis. Extreme temperatures (39-42°C), low air moisture content (35-50%) and water depth above 10 cm3 and 15 cm3 for Anopheles and Culex mosquitoes, respectively reduced their survival in captivity. There was apparently no relationship between larval mortality due to high air temperatures and low percentage relative humidity in breeding media, but there was significant difference (P<0.05) in mortality of adults due to high air temperatures above 36°C and larvae due to high volumes of water above 8 cm3 and 15 cm3 of Anopheles and Culex, respectively. Aquatic and air temperatures of 26.5-28°C and 33-36°C were found ideal for larval and adult survival, respectively. Watering twice daily the rooftops of the breeding cages that were partially covered by grass (Pennisetum spp.) during extreme weather conditions (March-May) artificially controlled the air temperature by reducing it from 41.5 to 33.5°C and its effects lasted for 1 to 2 h each watering. This decreased the adult mortality from 35.5% at 41.5°C to 23.5% at 33.5°C (12% increase in survival). Optimum relative humidity of 68.0% (60-75%) was preferred by both Anopheles and Culex mosquitoes for development in captivity, respectively.

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