1. Does geraniol reduce the risk of
biting by female Aedes aegypti on
human volunteers?
Frederique Marie Santos Uy
Supervisor: Professor. Gordon Hamilton

2. Aedes aegypti (A. aegypti)
• Worldwide distribution
(exception of the Arctic and
Antarctic Circle).
• Easily recognisable by silver
markings on the thorax.
• Poses as a major biting nuisance.
Agro, 2012.
WHO. (2009)

3. A. aegypti host choice and interaction
• A. aegypti females are anthropophilic and
zoophilic.
• Female mosquitoes possess a high innate drive
to blood-feed.
• Triggers that drive blood feeding behaviour;
De Jong et al., 1995; Eiras et al., 1994; Lehane, 2005; Muir et al., 1992; Peterson et al., 1951.
HEAT
HUMIDITY
VISION
OLFACTORY CUES

4. A. aegypti as a disease vector
• Acts as a vector for dengue.
- 96/360 million cases manifest clinically.
WHO. (2009)
There is NO specific treatment available for dengue.
• Vector is widespread.
- Current chemical vector control leads to
insecticide resistance.
The use of repellents are highly recommended for
dengue.

5. What is a repellent?
• A substance that deters arthropod-human
interactions.
- Gold standard repellent is N,N-diethyl-3-
methylbenzamide (DEET).
- Synthetic repellents are associated with health
risks.
• Botanical compounds as alternative repellents.
- Geraniol – high repellent efficacy towards A.
aegypti.
Choocote et al., 2007; Isman, 2006; Müller et al., 2009.

6. Geraniol
• Chemical name (E)- 3,7-dimethylocta-2,6-dienol.
• In nature it can be found in concentrations of 12-
25%.
• Predominantly used in the perfume industry.
Başer et al., 2010; Breitmaier, 2006.
The structure of geranyl pyrophosphate, the
precursor compound of geraniol (Başer et al., 2010).
Structural isometry of geraniol and nerol
(Breitmaier, 2006).

7. Conclusions from the study…
Bugga Bandz® wristbands (20% geraniol) is
NOT
as effective a repellent as Jungle Formula Insect
Repellent Maximum Spray (50% DEET).

8. 0
1
2
3
4
5
6
C1 C2 T1 C3
Timetakenforfirstmosquitoalightment(minutes)
Figure. 1 Average time taken for first mosquito alightment on the arm sleeve (minutes). (N=10) ± (SEM). C1- bare forearm,
C2- forearm with an inactive geraniol wristband, T1- forearm with active Bugga Bandz® wristband, C3- forearm treated with
DEET. *C3 significantly more repellent than C1, C2 and T1 (one-way ANOVA and Tukey’s test P<0.05).
*

9. Why?
- Air contamination.
- Hand-in-cage experiments.
- Difference in the mode of action of repellents.
Uy, 2014.Uy, 2014.

10. Future recommendations
• Carry out a comparative study with different
concentrations of geraniol.
• Hao et al., (2013), showed that botanical agents
act as repellents in a dose-dependent manner.
Figure. 2 Repellent effect of compounds at varied concentrations of botanical compounds (96%, 48%, 24%,
12% and 6%) on Aedes albopictus. The data from geraniol is shown in red square boxes (Hao et al., 2013).

11. • Geraniol in different formulations.
- A comparative study by Müller et al., (2009)
showed that geraniol displayed the highest
repellent efficacy in both diffuser and candle form.
Figure. 3 Average number of mosquitoes caught
after indoor diffuser experiments (N=9) ± STDEV.
*Geraniol significantly more repellent than all
others (P<0.05) (Müller et al., 2009).
Figure. 4 Average number of mosquitoes caught
after indoor candle experiments (N=9) ± STDEV.
*Geraniol significantly more repellent than all
others (P<0.05) (Müller et al., 2009).

12. Conclusion
Geraniol is not as effective as DEET.
• Further studies to identify and investigate the
efficacy of other botanical repellents are
required.
• Development of other vector control methods
are also required.

13. Thank you for your attention.
Questions?

14. References
Agro. (2012) Aedes aegypti: Vector of Dengue. URL: http://www.agro20.com/group/plagas-y-
entomologia-aplicada/forum/topics/aedes-aegypti-vector-del-dengue. Seen: April 18 2015.
Başer et al. (2010). Handbook of essential oils: Science, Technology and Applications. Taylor and
Francis Group, LLC, United States of America.
Breitmaier, E. (2006) Hemi-and monoterpenes. In: Terpenes. Wiley-VCH GmbH & Co. KGaA.
Weinheim, Germany.
Choochote et al. (2007) Repellent activity of selected essentila oils against Aedes aegypti. Fitoterapia
78, 359-364.
De Jong et al. (1995) Selection of biting sites on man by two malaria mosquito species. Experientia
50, 80-84.
Eiras et al. (1994) Responses of female Aedes aegypti mosquitoes (Diptera: Culicidae) to host odours
and convection currents using an olfactometer bioassay. Bulletin of Entomological Research 84, 207-
211.

15. Hao et al. (2013) Dose-dependent behavioural response of the mosquito Aedes albopictus to floral
odorous compounds. Journal of Insect Science 13, 1-8.
Isman, M. B. (2006) Botanical insecticides, deterrents and repellents in modern agriculture and
increasingly regulated world. Annual Review Entomology 51, 45-66.
Lehane, M. (2005) Biology of blood-sucking insects. Cambridge University Press, NewYork.
Muir et al. (1992) Aedes Aegypti (Diptera:Culicidae) vision-spectral sensitivity and other perceptual
parameters of the female eye. Journal of Medical Entomology. 29, 278-281.
Müller et al. (2009) Efficacy of the botanical repellents geraniol, linalool, and citronella against
mosquitoes. Journal of Vector Ecology. 34, 2-8.
Peterson et al. (1951) Studies of the responses of female Aedes aegypti (L) to a warm body and its
radiation. Bulletin of Entomological Research.42, 535-541.
WHO. (2009) Dengue: Guidelines for diagnosis, treatment, prevention and control. WHO Press,
Switzerland. pp 59-86.