Plant resting site preferences and parity rates among the vectors of Rift Valley Fever in northeastern Kenya

Arum, S O and Weldon, C W and Orindi, B and Tigoi, C and Musili, F and Landmann, T and Tchouassi, D P and Affognon, H D and Sang, R (2016) Plant resting site preferences and parity rates among the vectors of Rift Valley Fever in northeastern Kenya. Parasites & Vectors, 9 (310). pp. 1-10. ISSN 1756-3305

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Background Mosquito lifespan can influence the circulation of disease causing pathogens because it affects the time available for infection and transmission. The life-cycle of mosquitoes is determined by intrinsic and environmental factors, which can include the availability of hosts and suitable resting environments that shelter mosquitoes from extreme temperature and desiccating conditions. This study determined the parity rates (an indirect measure of survival) and plant resting preference of vectors of Rift Valley fever (RVF) in northeastern Kenya. Methods Resting mosquitoes were trapped during the rainy and the dry season using a Prokopack aspirator from vegetation, whereas general adult populations were trapped using CDC light traps. At each site, sampling was conducted within a 1 km2 area, subdivided into 500 × 500 m quadrants and four 250 × 250 m sub-quadrants from which two were randomly selected as sampling units. In each sampling unit, plants were randomly selected for aspiration of mosquitoes. Only Aedes mcintoshi and Ae. ochraceus were dissected to determine parity rates while all mosquito species were used to assess plant resting preference. Results Overall, 1124 (79 %, 95 % CI = 76.8–81.1 %) mosquitoes were parous. There was no significant difference in the number of parous Ae. mcintoshi and Ae. ochraceus. Parity was higher in the rainy season than in the dry season. Daily survival rate was estimated to be 0.93 and 0.92 among Ae. ochraceus and Ae. mcintoshi, respectively. Duosperma kilimandscharicum was the most preferred plant species with the highest average capture of primary (3.64) and secondary (5.83) vectors per plant, while Gisekia africana was least preferred. Conclusion Survival rate of each of the two primary vectors of RVF reported in this study may provide an indication that these mosquitoes can potentially play important roles in the circulation of diseases in northern Kenya. Resting preference of the mosquitoes in vegetation may influence their physiology and enhance longevity. Thus, areas with such vegetation may be associated with an increased risk of transmission of arboviruses to livestock and humans.

Item Type: Article
Divisions: Research Program : West & Central Africa
Uncontrolled Keywords: Parity, Survival, Resting preference, Vegetation, Rift Valley fever vectors, Mosquitoes
Subjects: Others
Depositing User: Mr Ramesh K
Date Deposited: 08 Jan 2017 08:11
Last Modified: 09 Jan 2017 15:06
Official URL:
Funders: This study was funded by IDRC Eco-health approach program. IDRC Grant Number: 105509-038.
Acknowledgement: This study received financial support from the IDRC Eco-health program. Icipe’s Capacity Building and Institutional Development Unit (CB&ID) provided a PhD scholarship to SOA. The technical support and dedication by James Wauna greatly contributed to our success. We acknowledge contributions by everyone involved in facilitating field activities; Lilian Igweta, Edith Chepkorir, Margaret Ochanda, Lisa Omondi and Joan Lichoti. We also thank the many people who assisted during the collection of data, analysis and preparation of this manuscript. Finally, we are grateful for the comments from anonymous reviewers that greatly improved the manuscript.
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