AU6914191A

AU6914191A - Pesticidal composition comprising azadirachtin, dialkyltoluamide and oil (geraniol and/or citronellal)

Info

Publication number: AU6914191A
Application number: AU69141/91A
Authority: AU
Inventors: Vincent Henry Guerrini
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-12-11
Filing date: 1990-12-11
Publication date: 1991-07-18

Description

DIRACHTIN. E-__-K_3_TO_iI-J_I__E AND OIL (GERANIOL AND/OR CITRONELLAL)

The present invention relates to pesticidal compositions, and to methods of killing or repelling pests. In particular,, the invention relates to synergistic mixtures of pesticidal compounds.

Diethyltoluamide (DEET) is a known pesticidal compound having low toxicity to animals and is used in insect repellent compositions such as Aeroguard (Registered Trade Mark) . Oil of citronella is a natural oil containing geraniol and citronella with minor amounts of camphene, dipentene, linalool and borneol, which is extracted from fresh grass of Cymbopagon (Andropogan) nardus. Oil of citronella is also known as a pesticide with low toxicity to animals. However, DEET and oil of citronella individually are not effective in blocking the development of parasites, ectoparasites and insects except in high doses.

^In pending Australian Patent Application No. 60185/90, the present Applicant discloses a synergy which exists between the known pesticidal agents diethyltoluamide (DEET) and oil of citronella. The synergy between these agents is particularly effective in blocking the development of larvae, and the mechanism of action is believed to relate to the synthesis of chitin.

In pending Australian Patent Application

Nos. 75714/87, 11220/88, 11221/88 and 26320/88, the present Applicant describes the use of azadirachtin-rich extracts of neem seeds and other eliacious tress to inhibit pests such as blowfly larvae, lice and fleas. Azadirachtin-rich extracts from neem seeds have been used in Indian folk medicine for thousand years and this, together with recent laboratory toxicological tests, has shown azadirachtin to be of very low toxicity to vertebrates.

SUBSTITUTE SHEET It is an object of the present invention to provide a new pesticidal composition in which the components exhibit true synergy, and to provide a new method of killing or repelling pests in which synergy between pesticidal compounds allows the use of lower doses.

The present invention thus provides a pesticical composition comprising dialkyltoluamide, azadirachtin and an oil containing geraniol and/or citronellal.

The alkyl moieties in the dial ytoluamide are preferably C_χ - C₄ alkyl, more preferably ethyl. In a most preferred embodiment, the dialkyltoluamide compound is N,N-diethyl-m-toluamide.

The oil is preferably oil of citronella, but may be any oil containing genaniol and/or citronellal, such as the oils of lemon grass, lemon, rose, lavender and penny royal. Alternatively, any volatile oils with pesticidal or insect repelling properties may be used.

Preferably, the pesticidal composition comprises from 1 to 35% by volume of oil of citronella, from 2 to 30g per litre Azadirachtin and from 30 to 200g per litre DEET. The composition may also comprise di-n-propyl isochinchomerate, N-octyl bicycloheptene dicarboximide, and/or other substances with pesticidal or insect repelling properties.

In order to prevent rapid oxidation of the azadirachtin, the carrier is preferably non-aqueous, more preferably alcoholic.

The invention also relates to a method of killing or repelling pests comprising applying dialkyltoluamide, azadirachtin and an oil containing geraniol and/or citronellal to the pests or their surroundings. The dialkyltoluamide, azadirachtin and the oil may be applied together or sequentially.

Further preferred embodiments of the invention shall become apparent from reference to the Examples.

Example

One litre of a liquid pesticidal/insect repelling composition may be made by mixing the following:

Oil of Citronella 10 to 350ml

Lanolin 0.1 to 4g

Fatty Acid (e.g. Oleic acid) 5 to 100ml

Meliaceous extracts containing

5% azadirachtin 40 to 600ml or Pure azadirachtin 2 to 30g

Triclosan 0.17 to 1.16

N,N, Diethyl-M-Toluamide 30 to 200g

Di-n-propyl Isochinchomerate 6 to 46g

N-octyl bicycloheptene 1.5 to 10.5g

Alcohol (e.g. ethanol) Remainder

Comparative Examples

The following liquids were mixed in different combinations to produce the preparations used in comparative Examples 1 to 4:

(a) Oil of citronella ("CIT").

(b) Aerogard Tropical Strength ("ATS") - containing 190g/kg DEET, 43.5g/kg di-N-propyl isochinchomerate, lOg/kg N-octyl bicycloheptene dicarboximide, and l.lg/kg Triclosan (a preservative) in a solvent comprising alcohol and lemon grass oil. (c) Aerogard Normal Strength ("ANS") - containing 96g/kg ethyl hexane diol (EHD), 27.2g.kg/di-N-propyl isochinchomerate, and 18g/kg N-octyl bicycloheptene dicarboximide in a solvent comprising alcohol and lemon grass oil.

(d) Alcoholic Neem extract ("Neem") containing 6% by weight azadirachtin.

(e) Alcoholic spirit ("ALC") comprising 96% ethanol

Comparative Example 1 - three liquid preparations were made up by mixing components (a) to (e) set out above in the proportions set out in Table 1A.

TABLE 1A

Preparations 1-1, 1-2 and 1-3 were used to treat respective groups of six greyhound dogs. Each treatment consisted of a single application of the preparation by spraying 40-50ml on each dog and rubbing this into the skin and fur. Each dog's kennel was sprayed with 40ml per square metre of the respective preparation.

Table IB shows the mean number of fleas counted on each group before treatment (Day 0), and at 2, 8 and 17 days after treatment. The percentage increase or decrease in the number of fleas is given in parentheses.

TABLE IB

As can be seen in Table IB, a single application of preparation 1-1 containing Oil of Citronella, DEET and Azadirachtin reduced the flea population on the dogs by 94% by Day 2, and resulted in a reduction in the flea population of 45% after 17 days. In contrast, preparation 1-2 in which the DEET in preparation 1-1 was substituted by EHD, and preparation 1-3 which did not include azadirachtin, reduced the flea population after 17 days by only 22% and 25% respectively.

Comparative Example 2 - two liquid preparations were made up by mixing components (a) to (e) in the proportions set out in Table 2A. TABLE 2A

Preparations 2-1 and 2-2 were used to treat respective groups of eight greyhound dogs. Each treatment consisted of a single application of the preparation by spraying 40-50ml on each dog and rubbing this into the skin and fur. Each dog's kennel was sprayed with 40ml per square metre of the respective preparation.

Table 2B shows the mean number of fleas counted on each group before treatment (Day 0), and at 2, 6 and 13 days after treatment. The percentage increase or decrease in the number of fleas is given in parentheses.

TABLE 2B

As can be seen in Table 2B, a single application of preparation 2-1 according to the invention reduced the flea population by 92% by Day 2, with a reduction of 57% after 13 days. In contrast, preparation 2-2 which did not contain DEET or oil of citronella reduced the flea population after 13 days by only 9%.

Comparative Example 3 - eight liquid preparations were made up by mixing components (a) to (e) in the proportions set out in Table 3A.

TABLE 3A

The preparations were used to treat respective groups of three greyhound dogs. Each treatment consisted of a single application of the preparation by spraying 40-50ml on each dog and rubbing this into the dog's skin and fur. Some kennels were sprayed with 40ml per square metre of the respective preparation.

Table 3B shows the mean number of fleas counted on each group before treatment (Day 0), and at 2, 12 and 20 days after treatment. The percentage increase or decrease in the number of fleas is given in parentheses, and the number of kennels treated in each group is given. In the untreated control group, one kennel was sprayed with 40ml per square metre of a solution made by dissolving 30ml of the neem extract in 1 litre of water.

TABLE 3B

:.5

16

15

25

25 As can be seen from Table 3B, with the exception of the control group each of the treatments achieved a substantial reduction in the flea population after 2 days. However, only preparations 3-1 and 3-2 according to the present invention resulted in a 0 reduction of over 50% after 20 days. From a comparison of the results for preparation 3-1 with those for preparations 3-3 and 3-4, it is apparent that only a small amount of oil of citronella is required to show a synergistic effect with DEET and 5 azadirachtin. Comparative Example 4

The following preparations were made up:

TABLE 4A

Four groups of greyhound dogs were sprayed with an initial treatment of 40-50ml of each of the preparations, and thereafter sprayed with 5-10ml of each preparation at 3, 10, 28, 48 and 80 days after the initial treatment. The number of fleas on each group of dogs was recorded before the initial treatment (Day 0), and at 3, 10, 17, 28, 48, 80 and 120 days after the initial treatment, and the results are set out in Table 4B. TABLE 4B

It is apparent from Table 4B that only preparation 4-1 according to the present invention provided substantial long-term protection against fleas.

In a further aspect of the invention, it has been found that the application of neem extracts containing azadirachtin to the skin and coat of animals results in increased hair growth and reduced thickness of inflammed and eczematous patches of skin.

The results on Table 5 show the effect of one application of 50ml of alcoholic neem tree extract containing 6% azadirachtin on the mean rate of hair growth (mm/week) on greyhound dogs. The standard deviation for each mean is shown in parentheses. TABLE 5

The results on Table 6 show the effect of one application of 50ml of alcoholic neem tree extract containing 6% azadirachtin on the mean weight (Kg) of hair combed off greyhound dogs. The standard deviation for each mean is shown in parentheses.

TABLE 6

The results on Table 7 show the effect of one application of 50ml of alcoholic neem tree extract containing 6% azadirachtin on the mean thickness of inflammed and eczematous skin patches of greyhound dogs after 14 days. The standard deviation of each mean is shown in parentheses.

TABLE 7

It is not yet clear which of the components of the oil of citronella causes the synergy with DEET and azadirachtin. Preliminary results from further experimental work suggest that only small amounts of oil of citronella are required for the synergy to be displayed.

Although the present invention has been described with particular reference to the synergy between azadirachtin, oil of citronella and DEET, it is believed that the synergy will be effective with other dialkyltoluamides which may optionally be substituted with moieties which do not adversely affect the synergy, such as halogen, C_j-^ alkyl and nitro groups. Similarly, it is believed that other oils or compositions containing geraniol, citronellal and/or other components of oil of citronella will also exhibit a synergy with azadirachtin and DEET or other dialkyltoluamides, and such combinations displaying synergy are intended to be embraced within the scope of the present invention.

The pesticidal and insect repellent compositions according to this invention display low toxicity to animals and birds and are suitable for direct application to the skin, coat or feathers of the animal or bird to prevent infestation by pests such as insects and arachnids.

Claims

1. A pesticidal composition comprising azadirachtin, dialkyltoluamide and an oil containing geraniol and/or citronellal.

2. A pesticidal composition according to claim 1 wherein the alkyl moieties of the dialkyltoluamide are independently selected from C_x to C₄-alkyl.

3. A pesticidal composition according to claim 2 wherein the alkyl moieties are both ethyl groups.

4. A pesticidal composition according to claim 3 wherein the dialkyltoluamide is N,N-diethyl-m-toluamide.

5. A pesticidal composition according to claim 1 wherein the oil is oil of citronella.

6. A pesticidal composition according to claim 5 comprising from 1 to 35% by volume oil of citronella, from 30 to 200g per litre N,N-diethyl-_n-toluamide and from 2 to 30g per litre azadirachtin in an inert carrier.

7. A pesticidal composition according to claim 6 wherein the carrier is non-aqueous.

8. A pesticidal composition according to claim 7 wherein the carrier comprises ethanol.

9. A pesticidal composition according to claim 1 further comprising di-n-propyl isochinchomerate and/or N-octyl bicycloheptene.

10. A method of killing or repelling pests comprising applying dialkyltoluamide, azadirachtin and an oil containing genaniol and/or citronellal to the pests or their surroundings.

11. A method of killing or repelling pests on an animal or bird comprising applying dialkyltoluamide, azadirachtin and an oil containing geraniol and/or citronellal to the skin, coat or feathers of the animal or bird.

12. A method according to claim 10 or 11 wherein the dialkyltoluamide is N,N-diethyl-m-toluamide.

13. A method according to claim 10 or 11 wherein the oil is oil of citronella.

14. A method according to any of claims 10 or 11 wherein the pests are insects or arachnids.

15. A method of promoting hair growth on an animal comprising applying azadirachtin to the coat or skin of the animal.

16. A method of treating inflammed or eczematous skin on an animal comprising applying azadirachtin to the inflammed or eczematous skin.

17. A method according to claim 15 or 16 wherein the azadirachtin is applied as a solution of azadirachtin in ethanol.

SUBSTITUTESHEET