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Synergism between nonane and emanations from soil as cues in oviposition-site selection of natural populations of Anopheles gambiae and Culex quinquefasciatus
Willem Takken
Wageningen Universiteit en Research
Corresponding Author
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Background
Olfactory cues have been shown to have an important role in guiding gravid mosquito females to selected sites for egg laying. The objective of this study was to determine the influence of emanations from soil from a breeding site and the putative oviposition pheromone nonane on oviposition-site selection of natural populations of Anopheles gambiae sensu lato (s.l.) and Culex quinquefasciatus.
Methods
This field-based study was conducted in Mvomero District in East-central Tanzania. In a dual-choice experimental set up, clay bowls were dug into the ground and filled with one of the following treatments: (i) distilled water + autoclaved soil (control), (ii) distilled water + soil from a natural mosquito breeding site, (iii) distilled water + nonane and (iv) distilled water + nonane + soil from a natural breeding site. Soil was dried and autoclaved or dried only before use. After five days of incubation, larvae were collected daily for 10 days. The median number of larvae per bowl per day was used as outcome measure.
Results
Autoclaved soil had a significant attractive effect on oviposition behaviour of Cx. quinquefasciatus (median values ± s.e: 8.0±1.1; P<0.005) but no effect on An. gambiae (median value ± s.e: 0.0±0.2; P = 0.18). Nonane and emanations from untreated soil significantly and positively influenced the selection of oviposition sites by both An. gambiae s.l. (median values ± s.e.: 12.0 ± 2.0 and 4.5 ± 1.5, respectively; P< 0.0001) and Cx. quinquefasciatus (median values ± s.e.: 19.0 ± 1.3 and 17.0 ± 2.0, respectively; P<0.0001). A mixture of nonane and untreated soil caused a synergistic effect on oviposition behaviour in An. gambiae s.l. (median value ± s.e.: 23.5 ± 2.5; P<0.0001) compared to either nonane (median values ± s.e.: 12.0 ± 2.0; P<0.0001) or untreated soil alone (median value ± s.e.: 4.5 ± 1.5; P<0.0001). A synergistic effect of nonane mixed with untreated soil was also found in Cx. quinquefasciatus (median value ± s.e.: 41.0 ± 2.1; P<0.0001) compared to either nonane (median value ± s.e. 19.0 ± 1.3; P<0.0001) or untreated soil alone (median value ± s.e.: 17.0 ± 2.0; P<0.0001). The oviposition activity index for An. gambiae was 0.56 (P< 0.001) and for Cx. quinquefasciatus 0.59 (P<0.0001).
Conclusion
The larval pheromone nonane and emanations from breeding-site soil both induced oviposition in wild An. gambiae s.l. and Cx. quinquefasciatus, with a synergistic effect when both stimuli were present simultaneously. This is the first study in which nonane is shown to cause oviposition under natural conditions, suggesting that this compound can potentially be exploited for the management of mosquito vectors.
Keywords
Oviposition, pheromone, nonane, breeding-site soil, Anopheles gambiae, Culex quinquefasciatus, Tanzania
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This preprint is under consideration at Malaria Journal. A preprint is a preliminary version of a manuscript that has not completed peer review at a journal. Research Square does not conduct peer review prior to posting preprints. The posting of a preprint on this server should not be interpreted as an endorsement of its validity or suitability for dissemination as established information or for guiding clinical practice.
Learn more about In Review
Research
Synergism between nonane and emanations from soil as cues in oviposition-site selection of natural populations of Anopheles gambiae and Culex quinquefasciatus
Willem Takken
Wageningen Universiteit en Research
Corresponding Author
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
Peer Review Timeline
CURRENT STATUS: Under Review
Version 2
Posted 12 Jan, 2021
No community comments so far
Editor assigned
On 29 Dec, 2020
Submission checks complete
On 29 Dec, 2020
Editor invited
On 29 Dec, 2020
Version (no preprint)
Posted 14 Dec, 2020
Editorial decision: Minor Revision
On 14 Dec, 2020
Editor assigned
On 13 Dec, 2020
Submission checks complete
On 13 Dec, 2020
Editor invited
On 13 Dec, 2020
This version was not preprinted
Version (no preprint)
Posted 03 Dec, 2020
Editorial decision: Minor Revision
On 03 Dec, 2020
Editor assigned
On 02 Dec, 2020
Submission checks complete
On 02 Dec, 2020
Editor invited
On 02 Dec, 2020
This version was not preprinted
Version (no preprint)
Posted 29 Nov, 2020
Editorial decision: Minor Revision
On 29 Nov, 2020
Editor assigned
On 28 Nov, 2020
Submission checks complete
On 28 Nov, 2020
Editor invited
On 28 Nov, 2020
This version was not preprinted
No comments provided
Editorial decision: Minor Revision
On 31 Oct, 2020
Review #1 received
Received 23 Apr, 2020
Reviewer #1 agreed
On 01 Apr, 2020
Reviewers invited
Invitations sent on 22 Mar, 2020
First submitted
On 21 Mar, 2020
Editor assigned
On 21 Mar, 2020
Submission checks complete
On 20 Mar, 2020
Editor invited
On 20 Mar, 2020
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
License:
This work is licensed under a CC BY 4.0 License. Read Full License
Background
Olfactory cues have been shown to have an important role in guiding gravid mosquito females to selected sites for egg laying. The objective of this study was to determine the influence of emanations from soil from a breeding site and the putative oviposition pheromone nonane on oviposition-site selection of natural populations of Anopheles gambiae sensu lato (s.l.) and Culex quinquefasciatus.
Methods
This field-based study was conducted in Mvomero District in East-central Tanzania. In a dual-choice experimental set up, clay bowls were dug into the ground and filled with one of the following treatments: (i) distilled water + autoclaved soil (control), (ii) distilled water + soil from a natural mosquito breeding site, (iii) distilled water + nonane and (iv) distilled water + nonane + soil from a natural breeding site. Soil was dried and autoclaved or dried only before use. After five days of incubation, larvae were collected daily for 10 days. The median number of larvae per bowl per day was used as outcome measure.
Results
Autoclaved soil had a significant attractive effect on oviposition behaviour of Cx. quinquefasciatus (median values ± s.e: 8.0±1.1; P<0.005) but no effect on An. gambiae (median value ± s.e: 0.0±0.2; P = 0.18). Nonane and emanations from untreated soil significantly and positively influenced the selection of oviposition sites by both An. gambiae s.l. (median values ± s.e.: 12.0 ± 2.0 and 4.5 ± 1.5, respectively; P< 0.0001) and Cx. quinquefasciatus (median values ± s.e.: 19.0 ± 1.3 and 17.0 ± 2.0, respectively; P<0.0001). A mixture of nonane and untreated soil caused a synergistic effect on oviposition behaviour in An. gambiae s.l. (median value ± s.e.: 23.5 ± 2.5; P<0.0001) compared to either nonane (median values ± s.e.: 12.0 ± 2.0; P<0.0001) or untreated soil alone (median value ± s.e.: 4.5 ± 1.5; P<0.0001). A synergistic effect of nonane mixed with untreated soil was also found in Cx. quinquefasciatus (median value ± s.e.: 41.0 ± 2.1; P<0.0001) compared to either nonane (median value ± s.e. 19.0 ± 1.3; P<0.0001) or untreated soil alone (median value ± s.e.: 17.0 ± 2.0; P<0.0001). The oviposition activity index for An. gambiae was 0.56 (P< 0.001) and for Cx. quinquefasciatus 0.59 (P<0.0001).
Conclusion
The larval pheromone nonane and emanations from breeding-site soil both induced oviposition in wild An. gambiae s.l. and Cx. quinquefasciatus, with a synergistic effect when both stimuli were present simultaneously. This is the first study in which nonane is shown to cause oviposition under natural conditions, suggesting that this compound can potentially be exploited for the management of mosquito vectors.
Figure 1
Figure 2
Figure 3
Figure 4