African Journal of Traditional, Complementary and Alternative Medicines African Ethnomedicines Network ISSN: 0189-6016 Vol. 3, Num. 2, 2006, pp. 79-83

African Journal of Traditional, Complementary and Alternative Medicines Vol. 3, No. 2, 2006, pp. 79-83

Short communication   

Adewoyin, F. B., Odaibo*, A. B. and Adewunmi, C. O.

Drug Research and Production Unit, ObafemiAwolowoUniversity, Ile-Ife; *Department of Zoology, University of Ibadan, Ibadan, Nigeria. E-mail: fbadewoyin@yahoo.com

Code Number: tc06021

Abstract

Repellent activity of Piper guineense and Xylopia aethiopica fruits oils in liquid paraffin were evaluated against adult Aedes aegypti in the laboratory. Results showed that repellency is dependent on both the concentration and time after application. P. guineense and X. aethiopica  oils showed complete protection from mosquito bite for 2h at 35%(v/v) and 30% respectively. The activity of eucalyptus oil (positive control), a commercial repellent, at 30% was only able to protect for 2h. Both oils used could be applied as repellents where protection from mosquito bite is sought for, over a short period of time.  

Key words: Piper guineense, Xylopia aethiopica, volatile oils, Aedes aegypti, repellency 

Aedes aegypti L. mosquito is known worldwide as the carrier of some major deadly diseases such as yellow fever, dengue fever, filariasis and encephalitis. These diseases are transferred by the bites from infective female mosquitoes.  Historically, the strategies for reducing the incidence of mosquito-bornedisease have been two-pronged, centering on habitat control(through chemical and biological means) and the use of personalprotection in the form of insect repellents (Fradin, 1998). Sharma and Ansari (1994) have reported the effectiveness of neem oil as an alternative and safe method of protection from mosquitoes. Citronella, the active ingredient of Cymbopogon nardus(L.) Rendle is most commonly found in "natural"or "herbal" insect repellents marketed in the United States.In addition, Citronella candles have been used to prevent bites by Aedes mosquitoesunder field conditions (Lindsay, et al, 1996).

X. aethiopica  (Dunal) A. Richard is known as Guinea or African pepper or spice tree. The fruits are used both as remedy and spice. The composition of its volatile oil was reported by Lamaty, et al (1987) to be diverse with mainly monoterpene hydrocarbons (66.6%) among which sabinene is the most abundant (23.9%), but with 25.1% of oxygenated compounds (essentially terpinen-4-ol and α-terpineol) and 8.3% of sesquinterpenene hydrocarbons (with 4.3% of α-murolene). Biological activities that have been carried out on X. eathiopica include antimicrobial (Thomas, 1989), oviposition deterrence and ovicidal properties against Callosobruchus maculatus in stored cowpea (Vigna unguiculata) seeds (Ofuya, 1990), insecticidal effect on the cowpea aphid Aphis craccivora Koch (Homoptera: Aphididae) (Ofuya and Okuku, 1994) and termite antifeedant property (Lajide et al, 1995).

P. guineense (Schum and Thonnhas) has  a reputation for its medicinal values. The plant is utilized in different forms, such as whole herbs, powders, extracts and vapours, for a variety of purposes  (Martins, et al, 1998). The leaves and fruits are essential ingredients in herbal drug preparations for cough, colds, bronchitis.  The essential oils have been reported to be rich in β-Pinene and β-caryophyllene, β-elemene, bycyclogermacrene and α-humulene (Martins, et al, 1998). The investigation of the chemical constituents of black pepper and other Piperaceae species has led to the identification of approximately 145 lipophilic amides as the major type of metabolites that are responsible for the insecticidal properties of these plants (Parmar et al 1997).

In spite of the extensive studies carried out on both plants, their volatile oils have not been tested against adult mosquitoes. The repellent results of theses oils on adult A. Aegypti mosquito are presented. 

Materials and Methods

Plant Materials 

The fruits of both P. guineense and X. aethiopica were purchased from herbs sellers at Ile-Ife (Osun State, Nigeria) market and authenticated in the department of Pharmacognosy, Obafemi Awolowo University, Nigeria. Essential oil from each plant was obtained by hydro-distillation in a Clevenger-type apparatus. 

Repellency Test 

Repellency was performed using the methods described by Gbolade, et al (2000). Graded concentrations (10-35%) of each oil in liquid paraffin as solvent were made. Appropriate oil solution was thinly applied using camelhair brush to the bare skin of the experimental bird. The bird was then placed on the roof of the netted cage. The number of mosquitoes that bit within 2 minutes was counted. This was done three times with 2 minutes intervals. The solvent liquid paraffin did not show any repellent activity.

 Percentage repellency was calculated thus:

C and T are numbers that landed on the control and treated respectively. Repellency was determined at hourly intervals for up to 5h. after application of oil solution. The result was compared to Eucalyptus oil, a commercial repellent. 

Results and discussion

Tables 1 and 2 contain the results of the repellency tests carried out on the adult A. aegypti mosquitoes. The results showed that repellency is dependent on both the concentration of oil in solution and time after application. Repellency increased with concentration and also decreased with time after application. At the tested concentrations (10-30%v/v), protection from mosquito bites varied from 11-100%. The oil of X. aethiopica showed greater repellency. It offered complete (100%) protection at 30% for more than 1h (Table 1); the effect of which was possible at 35% for P. guineense (Table 2). No significant protection could be obtained when using the oil at below 15% and 20% for X. aethiopica and P. guineense respectively. Protection from mosquito bites could not be sustained for a longer time due to evaporation of the oils from the skin shortly after application. Increased repellency at later time was possible at certain concentration levels, as majority of the mosquitoes had already taken their full blood meals at earlier times. Fewer numbers, which fed later, had not done so at the initial stage. The activity of eucalyptus oil at 30% was similar to that of X.aethiopica at 20% and P, guineense at 20%.

Since the oil of X. aethiopica is showing greater protection, the use could be encouraged by rural dwellers that could not afford synthetic insecticides. Interestingly the fruits are cheaper and more abundant than that of P. guineense. Gbolade et al (2000) observed similar performances with the volatile oils of two Nigerian Ocimum species. The two oils demonstrated pronounced bite protection (≥70%) for 2 to 3 hours at all the concentrations tested after application of oil. The repellency was said to be comparable to a commercial wipe containing synthetic repellents. Also Oyedele et al (2000) reported good concentration-dependent repellency for the essential oil a Lamiaceous herb, Hermizygia welwitschii (Rolfe) M. Ashby. Complete protection was observed within 2h after application of sample.

In order to achieve a longer protection using any of the oils used in this experiment, it may be necessary therefore to consider reapplication after an expiration of 2h of the first use. It is suggested that the oils can be useful where protection from mosquito bites is sought for over a short period.  

References 

1. Fradin, M. S. (1998). Mosquitoes and Mosquito Repellents A Clinician's Guide. Ann Intern. Med. 128: 931-940.
2. Gbolade, A. A.; Oyedele, A.O.; Sosan M. B.; Adewoyin, F.B. and Soyelu, O.L. (2000). Moquito repellent activities of essential oils from two Nigerian Ocimum  species. J.Trop. Med. Plants. 1: 146-148.
3. Lajide, L., P. Escoubas, P.and Mizutani, J. (1995). Termite antifeedant activity in Xylopia aethiopica.  Phytochem 40(4): 1105-1112.
4. Lamaty, G., Menut, C., Bessiere, J. M., Amvam Zollo, P.H. and Fekam Boyom F. (1987). Aromatic Plants of Tropical Central Africa. I. Volatile Components of Two Annonaceae  from  Cameroun: Xylopia aethiopica (Dunal) A. Richard and Monodora myristica   (Gaertn.) Dunal. Flavour Fragrance Journal, 2: 91-94.
5. Lindsay, R. L, Surgeoner, G. A., Heal, J.D. and Gallivan, G. J. (1996). Evaluation of the efficacy of 3% citronella candles and 5% citronella incense for protection against field populations of Aedes mosquitoes. J Am  Mosq. Control Assoc. 12(2 Pt 1): 293-4.
6. Martins, A. P. Salgueiro, L., Vila, R., Tomi, F. Canigueral, S. Casanova, J., Proenca Da Cunha, A. and Adzet, T. (1998). Essential oils from four Piper Species. Phytochem. 49 (7): 2019-2023.
7. Ofuya, T. I. (1990).Oviposition deterrence and ovicidal properties of some plantpowders against Callosobruchus maculatus in stored cowpea (Vigna unguiculata) seeds. J. Agric. Sci. 115(3): 343-346.
8. Ofuya, T. I. and Okuku  I. E. (1994). Insecticidal effects of some plant extracs on cowpea aphid Aphis craccivora Koch (Homoptera: Aphidae). Anzeigerfuer Schaedlingskunde Pflanzenschutz Umweltschutz 67(6): 127-129.
9. Oyedele, A.O., Orafidiya, O. O., Lamikanra, A. and Olaifa, J. I. (2000). Volatility and mosquito repellency of Hemizygia welwitschii oil and its formulations. Insect Science  its Application20: 123-128.
10. Parmar, V. S., Jain, S. C., Bisht, K. S., Jain, R., Taneja, P., Jha, A. Tyagi, O. D. Prasad, A. K., Wengel, J., Oslen, C. E. and Boll, P. (1997). Phytochemistry of the genus Piper. Phytochem. 46:597-673. 
11. Sharma, V. P., and Ansari, M. A. (1994). Personal protection frommosquitoes (Diptera: Culicidae) by burning neem oil in kerosene. J. Med.Entomol. 31(3):505-507.
12. Thomas, O. O. (1989). Re-examination of the antimicrobial activities of Xylopia aethiopica, Carica papaya, Ocimum gratissimum and Jatropha curcas. Fitoterapia 60(2): 147-156.

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