WO1998057542A1

WO1998057542A1 - Compositions comprising ratite oil or active fractions thereof and methods of using these compositions as insect repellents

Info

Publication number: WO1998057542A1
Application number: PCT/US1998/009026
Authority: WO
Inventors: Pamela Gail Marrone; Denise C. Manker; Stephen Judd
Original assignee: Agraquest, Inc.
Priority date: 1997-06-16
Filing date: 1998-05-07
Publication date: 1998-12-23
Also published as: AU756465B2; EP0989804A1; AU7367298A; NZ501679A; CN1283959A; IL133486A0; JP2002504141A

Abstract

This invention provides compositions for repelling insects, particularly biting insects, such as mosquitoes, ticks, and biting flies comprising ratite oil, active fractions of ratite oil obtained by flash chromatography or compositions comprising mixtures of fatty acids found in ratite oil. Also provided are compositions for repelling insects comprising ratite oil, active fractions of ratite oil or compositions comprising mixtures of fatty acids found in ratite oil further comprising at least one additional insect repellent. Methods of repelling insects, particularly biting insects, are provided comprising topically applying ratite oil, active fractions of ratite oil, or compositions comprising mixtures of fatty acids found in ratite oil; or ratite oil, active fractions thereof, or compositions comprising fatty acids found in ratite oil and further comprising at least one additional insect repellent.

Description

COMPOSITIONS COMPRISING RATITE OIL OR ACTIVE FRACTIONS THEREOF AND METHODS OF USING THESE COMPOSITIONS

AS INSECT REPELLENTS

TECHNICAL FIELD This invention is in the field of topical insect repellents. More particularly, effective, natural and safe biting fly repellents comprising oil from ratites, which include rheas, emus, ostriches, kiwis and cassowaries, active fractions of ratite oil and compositions comprising ratite oil or active fractions thereof and citronella or citronella and saponin are provided. Compositions comprising ratite oil or active fractions thereof and at least one other insect repellent are also provided. In addition, compositions for repelling biting insects comprising a mixture of fatty acids are provided. Methods for repelling insects comprising applying such compositions are also provided. BACKGROUND ART

This invention relates to a compositions and methods for repelling insects, and more particularly to compositions and methods for repelling biting insects such as mosquitoes and biting flies, for example, ceratopogonid flies, using a natural ingredient, oil from ratites, which include rheas, emus, ostriches, kiwis and cassowaries, active fractions of such oils and compositions comprising ratite oil or active fractions thereof and at least one other insect repellent such as citronella or DEET, optionally, further comprising saponin. Also included are compositions for repelling insects comprising a mixture of certain fatty acids and methods for repelling insects comprising application of such compositions comprising certain fatty acids. Known natural oils that repel insects include rotundial (from the leaves of Vitex rotundifolia, Watanabe K et al. (1995) Biotech Biochem 59(10):1979-1980); citronella oil (e.g. U.S. Patent No. 5,346,922); eucalyptus oil (Watanabe et al. (1993) J. Agric. Food Chem. 41:2164-2166); neem oil (Sharma VP et al. (1993) J. American Mosquito Control Association 9(3):359-360); and oil of Hedeoma pulgioides, oil of anisum and oil of chrysanthemum (U.S. Patent No. 5,208,209). Another natural oil that has repellent activity is saponin (Croda from Sapindus). Saponin has been shown to repel lice and also serves to improve the spreading consistency of repellent compositions and reduce greasiness.

However, the compound most widely used as a topically-applied insect repellent is N,N-diethyl-m-toluamide (DEET). When applied to children's skin, DEET has been implicated in causing convulsions. DEET is also known to react with certain plastics and synthetic rubber and cause skin irritation (Watanabe et al. (1993), supra). As a result of these problems and other side effects, New York State had banned products comprised of 100% DEET.

The active fractions of the naturally-occurring insect repellents are also largely unknown. Methods of resolving heterogeneous compounds into chemical species are well- known in the art. For example, silica gel flash chromatography provides for high speed resolution of organic compounds (see, e.g., U.S. Patent No. 4,293,422). After separation, the eluted fractions can be recovered and tested for the activity of interest.

Franz Bencsits, U.S. Patent No. 5,589,181, has reported that certain Cl to C4 fatty acid alkyl esters and fatty alcohols preferably having 5 to 18 carbon atoms have insect repellent activity. Bencsits discloses that the Cl to C4 fatty acid alkyl esters can be obtained from C5 to C9 fatty acids present in rape-seed oil, sunflower oil, peanut oil, peanut butter, soy oil, safflower seed oil, cuphea oil, coconut oil, palm kernel oil, palm oil and fish oil. The fatty alcohols may be obtained from paraffin and/or ethene. Bencsits further discloses that in order to slow down the evaporation of the active substances, the

C 1 to C4 fatty acid alkyl esters and/or the fatty alcohol, a carrier can be provided consisting of natural or nature-identical vegetal and/or animal oils. Bencsits does not, however, teach or suggest the compositions of the instant invention.

Accordingly, there remains a need for a natural, safe substance that acts to repel insects, particularly biting insects, when topically applied to the skin. The active fraction(s) of such a substance are also needed as are effective compositions comprising ratite oil or active fractions thereof and compositions comprising ratite oil or active fractions thereof in combination with at least one other insect repellent such as citronella, DEET or saponin. Compositions comprising mixtures of fatty acids that effectively repel insects are also needed. SUMMARY OF THE INVENTION The present invention provides a method for repelling insects, particularly biting insects, comprising topically applying ratite oil, active fractions of ratite oil, or a composition comprising a mixture of fatty acids to a subject. Methods for repelling insects, particularly biting insects, comprising topically applying compositions comprising ratite oil, active fractions thereof or mixtures of fatty acids and at least one other insect repellent such as citronella or DEET to the skin of a subject are also provided. The invention further provides compositions for repelling biting insects comprising active fractions of ratite oil or a mixture of fatty acids or compositions comprising ratite oil, active fractions thereof or a mixture of fatty acids and at least one other insect repellent such as citronella, DEET or saponin.

BRIEF DESCRIPTION OF THE FIGURES Figure 1 shows the number of mosquitoes present on filter paper treated with water, sucrose or sucrose and diluted emu oil (sample 776) at 2.5 minute intervals. The solid triangles show water-treated filter paper controls. The open squares show sucrose-treated filter paper. The solid squares show sucrose-treated paper overlaid with undiluted sample 776. The open triangles show sucrose-treated paper overlaid with a 50% dilution of sample 776. The open circles show sucrose-treated paper overlaid with sample 776 diluted to 25%. Figure 2 shows the number of mosquitoes present on filter paper treated with water, sucrose, or sucrose and fractions of sample 776 at 5 minute intervals. The solid squares show water-treated paper. The open squares show sucrose-treated paper overlaid. The solid triangles show sucrose-treated paper overlaid with a sample 776. The open triangles show sucrose-treated paper overlaid with fraction FI. The solid circles show sucrose- treated paper overlaid with fraction F2.

Figure 3 shows the Η NMR spectrum of the FI fraction of emu oil. Figure 4 shows the 'H NMR spectrum of the F2 fraction of emu oil. Figure 5 shows the average number of mosquitoes biting test limbs per ten minute intervals. MODES FOR CARRYING OUT THE INVENTION Throughout this application, various publications, patents and patent applications are referred to by an identifying citation. The disclosures of these publications, patents and patent applications are hereby incorporated by reference into this application to more fully describe the state of the art to which this invention pertains.

The present invention provides methods of repelling insects, particularly biting insects, using oil from ratites, which include rheas, emus, ostriches, kiwis and cassowaries, and is a natural and safe substance. The invention also includes methods of repelling insects comprising applying active fractions of ratite oils. The present invention also provides compositions for repelling insects comprising fatty acids that have a repellent effect. The invention also provides for methods of repelling insects comprising applying such compositions comprising mixtures of fatty acids topically. In a preferred embodiment, pure ratite oil is applied to the skin. In another preferred embodiment, diluted ratite oil is topically applied. In yet another preferred embodiment, an active fraction of ratite oil is applied to the skin. In a further preferred embodiment, a composition comprising ratite oil or an active fraction thereof and at least one other insect repellent is applied to the skin. Suitable insect repellents that can be combined with ratite oil or an active fraction thereof include, but are not limited to, N,N-diethyl-m-toluamide (DEET) citronella oil, rotundial oil, eucalyptus oil, neem oil, oil of Hedeoma pulgioides, oil of anisum, oil of chrysanthemum and saponin.

The present invention further provides compositions for repelling biting insects comprising ratite oil, active fractions of ratite oil or a mixture of fatty acids. Also included are compositions comprising ratite oil, an active fraction thereof or a mixture of fatty acids and at least one other insect repellent. Suitable insect repellents that can be combined with ratite oil, an active fraction thereof or a composition comprising a mixture of fatty acids include, but are not limited to, N,N-diethyl-m-toluamide (DEET), citronella oil, rotundial oil, eucalyptus oil, neem oil, oil of Hedeoma pulgioides, oil of anisum, oil of chrysanthemum and saponin.

Compositions comprising ratite oil, an active fraction thereof or a mixture of fatty acids and at least one other insect repellent were found to exhibit surprisingly unexpected synergistic results. The repellent activity of these compositions was much greater than either ratite oil, active fractions of ratite oil, a mixture of fatty acids or the other insect repellent alone. This synergistic effect was also observed with diluted preparations of ratite oil and another insect repellent.

The following examples are presented as a further guide to the practitioner of ordinary skill in the art, and are not to be construed as limiting the invention in any way.

Examples Example 1 : The effect of emu oil on frequency of mosquito lands and bites

To determine if emu oil was an effective mosquito repellent, pure emu oil (Zoogen, Inc., Davis, Ca) was applied to one hand of a volunteer. The other hand was left untreated. Each hand was placed in a nylon mesh cage containing mosquitoes (Aedes aegyptϊ) and the number of mosquitoes which landed and/or bit in 30 seconds was recorded. The experiment was performed in duplicate. Results of the experiments were averaged and are summarized in Table 1.

Table 1

These results demonstrate that topically applied emu oil is an effective mosquito repellent. It greatly reduces the number of mosquitoes which land, and completely eliminates biting. Example 2

The effectiveness of emu oil as a mosquito repellent over time

To determine how long topically applied emu oil maintains efficacy as a mosquito repellent, the treated hand was exposed to a cage of mosquitoes at 15, 30 and 60 minutes after application. The number of lands and bites were compared at each time point with the untreated hand. Results from duplicate experiments were averaged and are presented in Table 2. Table 2

These results show that emu oil remains an effective mosquito repellent for at least 30 minutes. Example 3 The effectiveness of diluted emu oil

To determine the effectiveness of diluted emu oil, the emu oil was diluted with ethyl acetate to a fixed percentage, applied to one hand and inserted into a mosquito cage. The number of lands were recorded. The experiments were performed in duplicate at each dilution level. Results are shown in Table 3.

Table 3

These results demonstrate that dilute amounts of emu oil effectively repel mosquitoes. At a dilution as low as 1%, emu oil reduces by one-half the number of mosquitoes which land. At 25%) emu oil, the number of mosquito lands drops to one-tenth of lands on an untreated hand. Thus, emu oil is an effective insect repellent at a concentration of 1% or higher.

Example 4

Fractionation of emu oil and the effectiveness of the fractions An 850 mg sample (776) of emu oil was steam-distilled and fractionated using silica flash chromatography (Baker silica gel, 40 μm), essentially as described in Still et al.

(1978) J Organic Chem. 43:2923. Two major components of the sample were eluted from the column with 100% hexane and 25% ethyl acetate/hexane. Fractions were analyzed by thin layer chromatography (TLC) on silica plates developed with 50% hexane/ethyl acetate. Components on the TLC plates were observed by exposing the plates to UV light

(indicating UV chromophores) and spraying plates with vanillin/sulfuric acid (indicating the presence of higher alcohols, sterols, phenols or essential oils). 430 mg of a clear oil. termed F2, was found to be UV active and reactive to vanillin/sulfuric acid. The second component, 380 mg of a pale yellow oil termed FI, was not UV active and did not stain with vanillin. FI and F2 fractions were analyzed by Η NMR (300 MHz, CDC1₃) as shown in Figures 3 and 4.

A mosquito repellent bioassay was performed by treating wedges of filter paper with sucrose overlaid with either an aliquot of the crude sample 776, FI or F2. Filter paper treated with water or sucrose served as controls. Samples of FI and F2 were tested at full- strength or diluted with corn oil to 50% or 25% of full-strength. At regular time intervals, the number of mosquitoes which landed and fed on the wedges of filter paper was recorded. Results are shown in Figures 1 and 2.

As shown in Figure 1, even diluted to 25% of full-strength, the crude sample (776) greatly reduces the number of mosquitoes landing on the sucrose paper. In addition, Figure 2 shows that both the FI and F2 fractions of sample 776 at full-strength and diluted to 50%) or 25% of full-strength were effective in repelling mosquitoes when compared to the sucrose-treated control. Example 5

The effect of emu oil as a tick repellent

To determine if emu oil was an effective tick repellent, a test subject's hands were treated with emu oil while the fingers of the hand were left untreated. As a positive control, Ultrathon (3M, Minneapolis, MN) was applied to the hand and the fingers were left untreated. An untreated hand was used as a negative control. Unfed nymphal Western

Black-legged ticks were placed on the fingers of the hands and observed as they climbed toward the treated or untreated skin of the hand. Ticks crossing onto the treated skin were scored as "crossing." Those not crossing were scored as "repelled." Ticks were removed after a single score was recorded. Repellency is calculated as the proportion of all trials in which a tick is repelled. For example, 8 repels in 10 trials provides a repellency of 80%.

In this study, each subject tested a tick at 15 minute intervals for 2 hours and 15 minutes.

The results are shown below:

Negative control - untreated skin - 0% repellency Positive control Ultrathon (3M) - 70% repellency

Emu oil - 40%) repellency

There was no indication that the repellency declined over the two hour test period.

Example 6

The effect of a composition of emu oil and citronella on frequency of mosquito bites To determine if citronella would enhance the mosquito repelling effect of emu oil, the repellent activity of emu oil alone and a composition comprising emu oil and citronella (30 drops of 100%) oil of citronella/25 mL of pure emu oil) were compared to a positive control, Ultrathon® (3M, Minneapolis, MN, approximately 31%> DEET). Oil of citronella, Cymbopagon nardus, was obtained from Aura Cacia, Weaverville, CA. Testing was conducted in the Florida Keys, namely Big Pine Key and Little Pine

Key. During testing, the air temperature was 24-26°C, with clear skies and slight wind.

Aedes taeniorhynchus accounted for >99% of mosquitoes that approached or attacked subjects.

In the first study, three subjects applied pure emu oil, one subject applied Ultrathon, and two subjects served as negative controls. In the second study, oil of citronella was added to the emu oil. Three subjects applied the composition comprising emu oil and citronella, two subjects applied Ultrathon, and two subjects served as negative controls. Six of the participants were employees of the Monroe County, Florida, Mosquito Control Service. Treatments were evenly divided among leg and arm surfaces. The surface areas of treated surfaces were calculated for each subject in advance of the application. The test materials were applied at dosage rate of approximately

3 mL/650 square centimeters of surface area.

Test subjects counted and recorded bites in a series of 10 minute periods. Counts were recorded on data sheets. In the first study, the testing period was two hours, with 12 consecutive 10 minute recording periods. In the second study, the test was interrupted during two brief windy periods by the need to move to more productive locales (i. e. , places with higher biting rates) within the test sites. As a result, the total testing period including the interruption was two hours and twenty-five minutes.

Ambient biting rates were measured throughout the study by the subjects with untreated control limbs. The average ambient biting rates were sufficient for testing in both studies and ranged between 17 and 70 bites per 10 minute interval (mean = 38.5; see

Figure 5).

Both emu oil and the positive control, Ultrathon, repelled mosquitoes over the test periods. A composition comprising emu oil and oil of citronella was particularly effective as a repellent (see Figure 5). The repellent properties of emu oil alone reduced the number of bites to an average of 5.7 bites per ten minutes. The composition comprising emu oil and citronella approximated the positive control, Ultrathon, with 0.8 bites per ten minutes for the emu oil/citronella composition compared to 0.2 bites per ten minutes for Ultrathon. Over the testing period, emu oil, a composition comprising emu oil and citronella and Ultrathon substantially reduced biting rates from Aedes taeniorhynchus. A composition comprising emu oil and citronella was much more effective than emu oil alone and offers protection comparable to that offered by mosquito repellents registered by the U.S. Environmental Protection Agency (EPA). No pattern of diminishing repellency over time was observed for emu oil and citronella. Example 7

The effect of a composition of emu oil, citronella and saponin on the biting frequency of ceratopogonid biting flies

To determine the efficacy of a composition comprising emu oil, citronella and saponin as a biting insect repellent, eight (8) human subjects took part in an experiment wherein three (3) subjects were treated with emu oil alone or emu oil with citronella and saponin. Three other subjects served as the negative controls while two subjects were treated with two commercially available insect repellents, Ultrathon™ , a DEET-based repellent, and Treo™, a plant-based repellent. Testing was conducted at three sites: a) on Big Pine Key, Florida; b) at Fairchild Tropical Gardens, Miami, Florida; and c) Hopkins

Village, Belize, Central America. Temperatures ranged from 21-24°C, the sky was clear and the winds were slight during each testing period.

Two preparations of emu oil were prepared for testing: a) 100%) emu oil alone; and b) 20 mL emu oil plus 30 drops of oil of citronella and 2 mL saponin (Croda, from Sapindus).

The two commercially available repellents used as comparative controls were: a) Ultrathon™ (3M®, Minneapolis, MN, a United States Environmental Protection Agency (EPA)-registered DEET-based product, approximately 32%) DEET); and b) Treo™ (Primavera Laboratories, Inc.®, SPF 15 lotion with 0.05% citronella). The negative control was untreated skin.

The test materials were applied either to the lower arm or lower leg skin of the study subjects. The areas of treated skin surfaces were calculated for each subject in advance of the application. Applications of the test materials, except Ultrathon, were made at a dosage of 3.0 mL/650 cm², a dosage comparable to that used in studies of herbal repellents for EPA registration. Ultrathon was applied at the manufacturer's recommended dosage of 1 mL/650 cm².

Each test subject recorded the number of bites received by ceratopogonid biting flies on treated or control surfaces during sequential sampling periods that began every 10 minutes, the overall test duration being approximately 1 hour. The EPA recognizes 1 hour as the required protection duration for claims of repellency to small biting flies. The results are shown in Table 4 below. Table 4

Biting rates were much lower on each of the test materials than with the control. Biting rates with emu oil and with the emu oil, citronella and saponin composition were much lower than with the control and lower than the EPA-registered herbal repellent, Treo.

The emu oil, citronella and saponin composition prevented biting altogether in many of the sampling periods, with confirmed bites (a bite followed by another bite within 30 minutes) recorded only on subject 1 in the first sampling period and subject 3 in the third sampling period. Thus, emu oil has a pronounced synergistic effect when combined with a herbal repellent, such as citronella.

Example 8 The synergistic repellent effects of emu oil

A preparation of emu oil was prepared wherein the emu oil was diluted to a final concentration of 0.02% with ethanol. OFF! Skintastic™ (S.C. Johnson) was diluted with ethanol to a final concentration of 0.01 %. A 1 : 1 solution (by volume) of the diluted OFF! and the diluted emu oil was prepared. A 1 :1 :1 solution consisting of 10 mL of the diluted 0.01%) OFF!, 10 mL of the diluted 0.02% emu oil, and 10 mL of ethanol was prepared.

In order to determine whether emu oil has an additive and/or a synergistic effect in combination with other insect repellents, these preparations were tested alone and in combination. Each preparation was applied to the hand of a volunteer and exposed to a population of Aedes aegypti mosquitoes for 20 seconds. The test was repeated three times for each preparation. Positive control preparations were either 100%> emu oil or 100%> OFF!. Negative controls were untreated skin. The results of this testing are shown in Table 5 below.

Table 5 NUMBER OF INSECT BITES PER TREATMENT

These results show that diluted emu oil had both an additive and a synergistic repellency effect in combination with other diluted repellents, in this case a DEET-based repellent. Example 9

The NMR spectra of the active fractions of emu oil characterized in Example 4 above were found to correspond to spectra of fatty acids. Compositions comprising various percentages of certain fatty acids known to be present in emu oil were prepared and tested for repellent activity. Table 6 below shows the chemical composition of one such composition and comparative information vis-a-vis corn oil, which has been previously shown to be non-repellent, and soybean oil, which is a component of an insect repellent recently introduced to the market as BiteBlocker™ (Consep, Inc., Bend, OR). The percentages of fatty acids in corn and soybean oil listed in Table 6 are from deMan, John M, PRINCIPLES OF FOOD CHEMISTRY (Avi Publishing Co., 1980). The percentages of fatty acids in emu oil were obtained from FASTRAX Ratites, Inc., Santa Ynez, CA and were published in WO 92/08470 (Ghosh et al.) which reports the anti-inflammatory activity of emu oil.

Table 6

Testing was conducted as in previous experiments reported in the foregoing examples. Tests were conducted in the outdoors in a wildlife area in New Mexico in which the predominant species of mosquito is Aedes vexans, an aggressive biting insect. Tests were performed in the summer months in the early afternoon (1430-1630 hours, Test 1) and in the late afternoon/early evening (1515-1915 hours, Test 2) near a stream at an elevation of approximately 2500 meters. In two separate tests, four subjects in total applied approximately 2.5 mL of the fatty acid composition shown in Table 6 to one lower arm. The other lower arm of each subject was untreated and served as a control. Test l In Test 1, three subjects were exposed for a period of two hours. Ambient biting was estimated at three (3) bites per minute on each untreated lower arm. No bites were received by any of the test subjects on the treated arm surfaces over the two hour test period. Test 2 In Test 2, one subject was exposed for a period of four hours. The ambient biting rate per lower arm was measured in each of twenty-four (24) ten (10) minute periods. The ambient biting rate average 0.5 bites per minute and ranged from 0 to 1.5 bites per minute. The test subject received one bite on the treated lower arm surface at approximately 225 minutes after application of the composition. In contrast, the test subject received a total of 116 bites on the untreated control lower arm surface during the 240 minute test period.

Thus, these results demonstrate that compositions comprising mixtures of fatty acids present in ratite oil are effective as insect repellents.

Having now fully described this invention, it will be appreciated by those skilled in the art that the same can be performed within a wide range of equivalent parameters, concentrations and conditions without departing from the spirit and scope of the invention and without undue experimentation. While this invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modifications. This application is intended to cover any variations, uses, or adaptations of the inventions following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth as follows the scope of the appended claims.

Claims

CLAIMS What is claimed is:

1. A composition for repelling insects comprising ratite oil.

2. The composition of claim 1 wherein the ratite is selected from the group consisting of rheas, emus, ostriches, kiwis and cassowaries.

3. A composition for repelling insects comprising an active fraction of ratite oil.

4. The composition of claim 3 wherein the ratite is selected from the group consisting of rheas, emus, ostriches, kiwis and cassowaries.

5. The composition of claim 4 wherein said active fraction is a fraction of emu oil obtained by flash chromatography having the ^]H NMR (300 MHz, CDC1₃) spectmm of Figure 3 and that is ultraviolet light active and reactive to vanillin/sulfuric acid.

6. The composition of claim 4 wherein said active fraction is a fraction of emu oil obtained by flash chromatography having the ╬ù NMR (300 MHz, CDC1₃) spectmm of

Figure 4 and that is nonreactive to ultraviolet light and vanillin/sulfuric acid.

7. A composition for repelling insects comprising a mixture of fatty acids found in ratite oil.

8. The composition of claim 7 wherein the ratite is selected from the group consisting of rheas, emus, ostriches, kiwis and cassowaries.

9. The composition of claim 7 wherein the fatty acids are myristic acid, arachidonic acid, palmitic acid, stearic acid, linolenic acid, palmitoleic acid, oleic acid and linoleic acid.

10. The composition of any of claims 1 to 9, further comprising at least one additional insect repellent.

11 The composition of claim 10 herein the additional insect repellent is selected from the group consisting of N,N-diethyl-m-toluamide (DEET), citronella and saponin.

12 A method for repelling insects comprising topically applying a composition comprising ratite oil.

13 The method of claim 12 wherein the ratite is selected from the group consisting of rheas, emus, ostriches, kiwis and cassowaries.

14 A method of repelling insects comprising topically applying a composition comprising an active fraction of ratite oil.

15 The method of claim 14 wherein the ratite is selected from the group consisting of rheas, emus, ostriches, kiwis and cassowaries.

16. A method of repelling insects comprising topically applying a composition comprising a mixture of fatty acids found in ratite oil.

17. The method of claim 16 wherein the fatty acids are myristic acid, arachidonic acid, palmitic acid, stearic acid, linolenic acid, palmitoleic acid, oleic acid and linoleic acid.

18. A method for repelling biting insects comprising the step of topically applying a composition comprising a fraction of emu oil wherein the fraction is obtained by flash chromatography and has the ╬ù NMR (300 MHz, CDC1₃) spectrum of Figure 3 and is ultraviolet light active and reactive to vanillin/sulfuric acid.

19. A method for repelling biting insects comprising the step of topically applying a composition comprising a fraction of emu oil wherein the fraction is obtained by flash chromatography and has the ╬ù NMR (300 MHz, CDC1₃) spectmm of Figure 4 and is nonreactive to ultraviolet light and vanillin/sulfuric acid.

20. The method of any one of claims 12 to 19 wherein the composition further comprises at least one additional insect repellent.

21. The method of claim 20 wherein the additional insect repellent is selected from the group consisting of N,N-diethyl-m-toluamide (DEET), citronella and saponin.