| Title: | Discovery of an oviposition attractant for gravid malaria vectors of the Anopheles gambiae species complex |
| Author(s): | Lindh JM; Okal MN; Herrera-Varela M; Borg-Karlson AK; Torto B; Lindsay SW; Fillinger U; |
| Address: | "Department of Chemistry, Royal Institute of Technology, SE-100 44, Stockholm, Sweden. jenlindh@kth.se. Disease Control Department, London School of Hygiene & Tropical Medicine, London, WC1E 7HT, UK. okal.mike@gmail.com. Behavioural and Chemical Ecology Department, International Centre of Insect Physiology and Ecology, 00100, Nairobi, Kenya. okal.mike@gmail.com. Disease Control Department, London School of Hygiene & Tropical Medicine, London, WC1E 7HT, UK. manuelahv82@gmail.com. Behavioural and Chemical Ecology Department, International Centre of Insect Physiology and Ecology, 00100, Nairobi, Kenya. manuelahv82@gmail.com. Department of Chemistry, Royal Institute of Technology, SE-100 44, Stockholm, Sweden. akbk@kth.se. Behavioural and Chemical Ecology Department, International Centre of Insect Physiology and Ecology, 00100, Nairobi, Kenya. btorto@icipe.org. School of Biological & Biomedical Sciences, Durham University, Durham, DH1 3LE, UK. s.w.lindsay@durham.ac.uk. Disease Control Department, London School of Hygiene & Tropical Medicine, London, WC1E 7HT, UK. ufillinger@icipe.org. Behavioural and Chemical Ecology Department, International Centre of Insect Physiology and Ecology, 00100, Nairobi, Kenya. ufillinger@icipe.org" |
| DOI: | 10.1186/s12936-015-0636-0 |
| ISSN/ISBN: | 1475-2875 (Electronic) 1475-2875 (Linking) |
| Abstract: | "BACKGROUND: New strategies are needed to manage malaria vector populations that resist insecticides and bite outdoors. This study describes a breakthrough in developing 'attract and kill' strategies targeting gravid females by identifying and evaluating an oviposition attractant for Anopheles gambiae s.l. METHODS: Previously, the authors found that gravid An. gambiae s.s. females were two times more likely to lay eggs in lake water infused for six days with soil from a natural oviposition site in western Kenya compared to lake water alone or to the same but autoclaved infusion. Here, the volatile chemicals released from these substrates were analysed with a gas-chromatograph coupled to a mass-spectrometer (GC-MS). Furthermore, the behavioural responses of gravid females to one of the compounds identified were evaluated in dual choice egg-count bioassays, in dual-choice semi-field experiments with odour-baited traps and in field bioassays. RESULTS: One of the soil infusion volatiles was readily identified as the sesquiterpene alcohol cedrol. Its widespread presence in natural aquatic habitats in the study area was confirmed by analysing the chemical headspace of 116 water samples collected from different aquatic sites in the field and was therefore selected for evaluation in oviposition bioassays. Twice as many gravid females were attracted to cedrol-treated water than to water alone in two choice cage bioassays (odds ratio (OR) 1.84; 95% confidence interval (CI) 1.16-2.91) and in experiments conducted in large-screened cages with free-flying mosquitoes (OR 1.92; 95% CI 1.63-2.27). When tested in the field, wild malaria vector females were three times more likely to be collected in the traps baited with cedrol than in the traps containing water alone (OR 3.3; 95% CI 1.4-7.9). CONCLUSION: Cedrol is the first compound confirmed as an oviposition attractant for gravid An. gambiae s.l. This finding paves the way for developing new 'attract and kill strategies' for malaria vector control" |
| Keywords: | Animals Anopheles/*drug effects/*physiology Female Gas Chromatography-Mass Spectrometry Insect Vectors/*drug effects/*physiology Kenya Oviposition/*drug effects Pheromones/chemistry/*isolation & purification/metabolism Polycyclic Sesquiterpenes Terpenes/c; |
| Notes: | "MedlineLindh, Jenny M Okal, Michael N Herrera-Varela, Manuela Borg-Karlson, Anna-Karin Torto, Baldwyn Lindsay, Steven W Fillinger, Ulrike eng R01 AI082537/AI/NIAID NIH HHS/ R01AI082537/AI/NIAID NIH HHS/ Research Support, N.I.H., Extramural England 2015/04/18 Malar J. 2015 Mar 20; 14:119. doi: 10.1186/s12936-015-0636-0" |
