Study on Efficacy of Various Solvents and Extractions on Repelling
Forcipomyia Taiwana
Ching-Wen Lou1, Chao-Tsang Lu2, b, Ming-Chun Sie1 and Jia-Horng Lin3, 4, 5, a
1
Institute of Biomedical Engineering and Materials Science, Central Taiwan University of Science
and Technology, Taichung 40601, Taiwan, R.O.C.
2
Graduate Institute of Biotechnology, Central Taiwan University of Science and Technology,
Taichung 40601, Taiwan, R.O.C.
3
Laboratory of Fiber Application and Manufacturing, Department of Fiber and Composite Materials,
Feng Chia University, Taichung City 40724, Taiwan, R.O.C.
4
School of Chinese Medicine, China Medical University, Taichung 40402, Taiwan, R.O.C.
5
Department of Fashion Design, Asia University, Taichung 41354, Taiwan, R.O.C.
a
jhlin@fcu.edu.tw, bctlu@ctust.edu.tw
Keywords: Forcipomyia taiwana (F. taiwana), repellent effect, Cinnamomum osmophloeum Kaneh,
Cymbopogon excavates, Mentha.
Abstract. The bites of Forcipomyia taiwana (F. taiwana) cause swelling and pruritus in sensitive
skins, and are often prevented by synthetic repellents. The commercially available repellents are
composes of N,N-diethyl-3-methylbenzamide, long-term use of which may results in negative
influence on skins as well as nervous and immune systems. This study first examines how different
organic solvents influence on the repellent effect on F. taiwana, after which solvents are used for
the extraction of Cinnamomum osmophloeum Kaneh, Cymbopogon excavates, Mentha, Rosmarinus
officinalis, Salvia officinalis, and Eucalyptus globulus. The plant extracts are tested for their
repellent effect on F. taiwana with a Y-tube test. The experiment results show that of all solvents,
only water attracts F. taiwana, furthermore, with water as the solvent, except for Eucalyptus
globulus, all the other plant extracts, are repellent to F. taiwana.
Introduction
F. taiwana were long discovered by a Japanese scholar, Shiraki, in 1913, and their major habitat is
in dark and damp areas in eastern, central and southern Taiwan, such as bamboo groves, tussocks, and
mud flats in gutters. As a result, villages located in mountain edges or at the foot of the mountains
where are damp and dark and without weeds, are larvae’s favorite spots. In particular, F. taiwana live
and thus are mostly spotted in areas near pig farms and with poor drainage, areca plantation, tea
gardens, and bamboo groves.
Commercially available synthetic repellents contain N,N-diethyl-3-methylbenzamide compound,
which is added within a safe range; however, some studies point out that long-term use of this
ingredient may have an impact on the skin and nervous and immune systems [1]. According to the
finding of previous studies, the organic solvents, such as Methyl Alcohol, Ethanol, and acetone,
may pollute the environment and influence people’s immune system. These drawbacks thus make
water a preferred solvent for plant extracts, which serve as natural repellents [2]. Most repellents on
market are made of one or more than one plant matters, including Cinnamomum osmophloeum
Kaneh, Cymbopogon excavates, Cedrus deodara, Eucalyptus maculate, Pelargonium reniforme,
Mentha piperita, and Melia azedarach Linn [3, 4].
Moreover, previous studies also pointed out that plant extracts yielded from Cinnamomum
osmophloeum Kaneh, Cymbopogon excavates, Rosmarinus officinalis, and Salvia officinalis exhibit
a distinctive repellent effect on Aedes aegypti [5, 6]. This study thus aims to examine that whether
the organic solvents can attract or repel F. taiwana and the repellent performance of plant extracts
made of Cinnamomum osmophloeum Kaneh, Cymbopogon excavates, Mentha, Rosmarinus
officinalis, Salvia officinalis, and Eucalyptus globulus.
Experimental
Materials
Ethanol is purchased from M & J SCINTEK Co., Ltd., and both methyl alcohol and acetone are
purchased from Chonete Pure Chemicals, Taiwan, R.O.C. All the plants used in this study are
purchased from Feng Chiuun Chinese Herbal Medicine Store, Taiwan, R.O.C.
Experimental Procedure
15 g of plant matters are respectively cut into 3 to 5 centimeter long, placed in Erlenmeyer flask,
followed by an infusion of 300 ml of deionized water. Then, they are placed in a horizontal shaking
bath with a speed of 40 rpm at 40 ˚Cfor 24 hours, after which the extracts are filtrated.
Tests
Figure 1 illustrates the Y-tube, which is consisted of the odor end (B), control end (C), and odor
mixture end (A). On the control end is a blank filter paper. Each solvent is dripped on a filter paper,
which is then placed on the odor end, and the solvent is given five minutes to diffuse in the Y-tube.
Next, F. taiwana are released from the odor mixture end for 10 minutes, and their distribution inside
the Y-tube is then observed to determine the solvent that attracts F. taiwana. This particular solvent is
then used for the extraction of plants, and the resulting plant extracts are also tested with the Y-tube to
determine their repellent effects on F. taiwana.
Figure 1. Illustration of the Y-tube.
Results and Discussion
Repellent Effect of Water, Methyl Alcohol, Ethanol, Acetone, and Dilute Ethanol on F. taiwana
Figure 2 shows the repellent effect of different solvents. The amount of F. taiwana at the odor
end for methyl alcohol, ethanol, acetone, and dilute ethanol is low, which may be ascribed to a short
volatility of these organic solvents, which generates repulsive odor to these particular insects. By
contrast, these insects are fond of the odor released by water, which is exemplified by a relatively
higher number of the insects. Such a result may be due to the feature of the insects’ habitat, which is
damp, and thus they are fond of water as the solvent.
Figure 2. Repellent effect of various solvents on F. taiwana.
Repellent Effect of Extracts of Cinnamomum osmophloeum Kaneh, Cymbopogon excavates,
Mentha, Rosmarinus officinalis, Salvia officinalis, and Eucalyptus globulus
Figure 3 shows the repellent effect of various plant extracts. The repellent effect of water is
eliminated by experiment results of 3.1; therefore, the amount of the F. taiwana in the odor end for
each plant extract can directly reflect repellent effect of the extracts. Except for Eucalyptus globulus,
the rest extracts all demonstrate repellent effect on F. taiwana.
Figure 3. Repellent effect of various plant extracts on F. taiwana.
Conclusion
This study successfully proposes and produces natural repellents to F. taiwana. The use of water
as solvent does not influence the repellent effect of the plant extracts. Extracts made of Cinnamomum
osmophloeum Kaneh, Cymbopogon excavates, Mentha, Rosmarinus officinalis, and Salvia officinalis
are all mosquito-repellent. Only Eucalyptus globulus extract does not exhibit the repellent effect.
Acknowledgement
The authors would especially like to thank National Science Council of the Taiwan, for
financially supporting this research under Contract NSC 101-2221-E-166-002.
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