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Title: Resting Behaviour of Endophilic Anopheline Vectors in Three Ecological Zones of Southern Ghana and its Implications for the use of Entomopathogenic Fungi
Authors: Wilson, D.D.
Wilson, M.D.
Koekemoer, L.L.
Osae, M.Y.
University of Ghana, College of Basic and Applied Sciences Department of Nuclear Agriculture and Radiation Processing
Keywords: Resting Behaviour
Endophilic Anopheline Vectors
Ecological Zones
Southern Ghana
Issue Date: Sep-2014
Publisher: University of Ghana
Abstract: The aim of this study was to determine the resting behaviour and factors that influence the choice of resting sites by endophilic anopheline mosquitoes in southern Ghana. The study was carried out in six villages across three ecological zones of southern Ghana, including: the forest ecological zone (FEZ), the coastal savannah ecological zone (CSEZ) and the forest-transition ecological zone (FTEZ). For every mosquito collected, the indoor resting sites was characterised and microclimate at the actual resting site recorded using a data logger. In the laboratory, full diagnostics was carried out on a sub-sample. Resting devices constructed from different materials were tested in a screen house and in village rooms. The dominant anopheline vectors include Anopheles gambiae s.s., An. coluzzii and An. funestus. An gambiae s.s. was the most dominant species in the villages from the FEZ and FTEZ, whereas An. coluzzii was most dominant in the CSEZ. An. funestus was present in the FEZ and CSEZ but almost absent from the FTEZ. The two kdr mutations (L1014F and L1014S) were present in all the ecological zones and in both An. gambiae s.s. and An. coluzzii. This is the first report of the L1014S mutation from Ghana. The populations were highly anthropophagic and Plasmodium falciparum was present in populations from all the villages studied. Woody materials appeared to be the most preferred resting materials for An. gambiae, accounting for 47 % of all the resting sites for that species. They were also found on fabrics (26 %), wall materials (12 %), and roof materials (10 %). Similarly, An. funestus preferred to rest on woody materials (58 %), followed by wall materials (21 %), fabrics (11 %) and roofing materials (7 %). For An. coluzzii, fabrics were the most preferred resting materials (38 %) followed by roof materials (21 %), wooden materials (19 %) and wall materials (9 %). All the three vector species preferred to rest higher up the room and closer to the walls, with large proportions of An. gambiae s.s. (75.94 %), An. funestus (73.60 %) and An. coluzzii (58.19 %) found resting at heights above 200 cm from the floor. With reference to the nearest wall, high proportions of An. gambiae s.s. (68.38 %), An. coluzzii (80.98 %) and An. funestus (68.29 %) were collected within 50 cm from the closest wall. Although microclimatic conditions varied widely in the indoor environment and even at the specific resting sites, higher proportions of the endophilic anophelines were collected within narrow ranges of temperature (27-30 oC), relative humidity (65-75 %) and light intensity (0-20 Lux). Black felt and black cotton cloth were the most preferred resting devices for blood-fed females in both screen house trials and field. In general, the presence of the three most efficient vectors of malaria from indoor collections in southern Ghana and the fact that they were highly anthropophagic and effectively transmitting malaria is a high call for intensifying vector control efforts. Knowledge of the indoor resting behaviour of the major endophilic Anopheles vectors of southern Ghana paves the way for developing fungal spore deployment strategies for field implementation. This study has established that all the three endophilic Anopheles species in southern Ghana rest higher up in village rooms, prefer to rest on darker coloured materials in cool humid areas. It has further demonstrated that black felt and black cotton cloth are attractive to blood-fed females seeking resting sites to digest blood meal and develop their eggs. Guided by this knowledge, future research should focus on designing these preferred materials into resting devices that create suitable microhabitats to which endophilic anopheline mosquitoes can be attracted and contaminated with fungal spores. Further research is also needed to determine the efficacy and persistence of fungal spores on these preferred resting materials so as to determine application rates and frequency.
Description: Thesis(PhD)-University of Ghana, 2014
Appears in Collections:Department of Nuclear Agriculture and Radiation Processing

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