WO2005077175A1

WO2005077175A1 - Pesticide control

Info

Publication number: WO2005077175A1
Application number: PCT/AU2005/000159
Authority: WO
Inventors: Stephanie Smith
Original assignee: Bretts Pty Limited
Priority date: 2004-02-11
Filing date: 2005-02-10
Publication date: 2005-08-25

Abstract

A pesticidal composition, containing citronellic acid and/or one or more derivatives thereof, is disclosed. The composition is toxic and/or repellant towards termites and similar pests, particularly the subterranean termite Coptotermes acinaciformis. The composition can be applied as a pre-treatment for timer prior to construction from that timer or applied to existing timber-containing structures or to the ground surrounding existing timber-containing structures to form a protective barrier.

Description

TITLE: PESTICIDE CONTROL

THIS INVENTION relates to pesticides. In particular, it is directed, but not limited, to a pesticidal composition which is toxic towards termites and similar pests and to the use of that composition to exterminate and/or repel termites and similar pests from timber, and from buildings, fences and other constructions manufactured from timber.

Effective control of termites is a major problem throughout the world. Methods currently employed to control these pests generally spray a liquid pesticide formulation onto the soil before any foundations for constructions are laid, so that the water carriers, solvents, emulsifiers, etc. dry out, the active pesticide remaining in the soil as a termite barrier.

However, the majority of these pesticides are synthetic and with the general public increasingly questioning the use of synthetic chemicals in the environment, governments promulgate legislation which bans the use of such chemicals.

Accordingly, recent attempts to produce a more environment-friendly alternative include the use of a physical rather than a chemical barrier to prevent the termite or other pest species from reaching the area to be protected.

While these physical barriers may be an alternative, they are not as convenient to apply as a chemical composition. For example, excavation around the perimeter of an existing building is often necessary to apply a physical barrier, whereas a chemical composition can simply be sprayed around that same perimeter allowing the composition to seep into the soil around the building or possibly directly into the timber to be protected.

Also, such a physical barrier, while assisting to prevent the pest from reaching the area to be protected, fails to eradicate any pest which is already resident in the area or which has circumvented the barrier in some manner.

Further, a physical barrier, usually, is only installed after the building to be protected has been erected and the surrounding grounds landscaped, etc. These barriers are thus not suitable to pre-treat timber before that timber is used in construction.

Therefore, there remains a need for a chemical pesticide composition which is at least as similarly effective as the earlier synthetic compositions, which is both toxic and repellent to the pest but without the related environmental concerns, and can be used to pre-treat timber before any construction is commenced using that timber.

One composition which is toxic towards termites is described in the current applicants' international patent application no. PCT/AU98/00581 which discloses the extraction of Cypress pine material with a solvent (preferably a hydrocarbon, substituted hydrocarbon or an ester), the resultant extract being particularly effective against subterranean termites. Analysis of such an extract suggested that the terpene citronellic acid and/or a derivative thereof may be contributing to the activity of the extract. When the activity of the extract against termites was compared against the activity of citronellic acid it was surprisingly established that citronellic acid, either as a racemic mixture or in an optically active form, exhibited both significant toxicity and repellency towards those termites. As citronellic acid and its derivatives already have an established use in the food and cosmetic industries, and are thus deemed safe for use, this unexpected use as a pesticide and pest repellent offers another alternative to the prior art synthetic compositions discussed above.

Therefore, as a first aspect of the present invention, there is provided a method for the control of pests, said method including the application of an effective amount of citronellic acid and/or one or more derivatives thereof to an area requiring said control.

Preferably, the method is the application of an effective amount of citronellic acid to the area requiring control.

As a second aspect of the present invention, there is provided a pesticidal composition which is toxic to pests in a given area containing said pests and/or repels said pests from said area, said composition including an effective amount of citronellic acid and/or one or more derivatives thereof.

It will be appreciated that the compounds used in the present invention may be chiral. The present invention therefore relates both to the individual stereoisomers and to any mixtures thereof whether these mixtures include enantiomers and/or diastereoisomers.

Preferably, however, the present invention uses an effective amount of racemic citronellic acid to the area requiring control.

Optionally, the present invention may also include the use of a carrier, diluent or adjuvant. As used throughout the specification, the term "carrier or diluent" denotes an organic or inorganic, natural or synthetic material with which the citronellic acid and/or one or more of its derivatives is combined in order to facilitate the use thereof. This carrier or diluent is generally inert. Similarly, the term "adjuvant" has the usual meaning in the art to describe a material which aids the operation of an active component.

Although not limited to, the present invention is particularly effective against subterranean termites such as Coptotermes acinaciformis.

Preferred embodiments of the present invention will now be described with reference to the following examples.

Preparation of Samples (1)

Four (4) extracts (labelled 1 to 4) from Callitris columellaris F. Muell. obtained from four different geographical locations within Australia and a sample of S- citronellic acid (98% purity) (labelled 5) were dissolved in ethyl acetate to create respective six (6) 0.5% solutions and six (6) 1.0% solutions.

Test procedure (1)

Single separate filter papers were treated with the respective solutions by pipetting equal volumes of solution thereon. An equal volume of ethyl acetate (labelled 6) was placed onto six separate filter papers (solvent control). The treated filter papers were allowed to dry. Six further filter papers were selected for the untreated control (labelled 7). A single filter paper, either treated with a solution, solvent control or untreated was placed in a Petri dish, 100 termites (C. acinaciformis) added and the dish covered. The number of termites that had died in each dish were counted after 24, 48, 72, 96 and 168 hours. This method of laboratory bioassay allowed the simple assessment of termite mortality. The raw results of this bioassay are presented in the following Table 1 and the mean percentage mortality in Table 2.

Table 1

Table 2

It will be seen from the above tabulated results that there was 100% mortality at 24 hours for all samples that included S-citronellic acid which was comparable to, or better than, the Callitris' extracts. Mortality in the solvent and untreated controls was not evident until 168 hours.

Preparation of Samples (2)

Two (2) extracts A & B from Callitris columellaris F. Muell. were obtained from two different geographical locations (differing from those of Samples (1) above) within Australia. A first sample of extract A was dissolved in ethyl acetate to create six (6) 1.0% solutions (labelled 3). A second sample of extract A was dissolved in ethyl acetate to create six (6) 0.5% solutions (labelled 4). A first sample of extract B was dissolved in ethyl acetate to create six (6) 1.0% solutions (labelled 5). A second sample of extract B was dissolved in ethyl acetate to create six (6) 0.5% solutions (labelled 6). Samples of racemic citronellic acid (98% purity) were dissolved in ethyl acetate to create respective six (6) 0.4% solutions (labelled 7), six (6) 0.2% solutions (labelled 8), six (6) 0.1% solutions (labelled 9) and six (6) 0.05% solutions (labelled 10). Samples of S-citronellic acid (98% purity) were dissolved in ethyl acetate to create respective six (6) 0.4%, 0.2%, 0.1% and 0.05% solutions, labelled 11 , 12, 13 & 14 respectively.

Test Procedure (2)

The procedure was identical to that described above with reference to Test Procedure 1.

The raw results of the bioassay are presented in the following Table 3 and the mean percentage mortality in Table 4. Table 3

Table 4

It will be seen from the above tabulated results that both S-citronellic acid and racemie citronellic acid are equally more effective at a lower concentration than that of the Callitris' extracts. It should be noted at this time that the cost of commercially available racemie citronellic acid is significantly lower than that of S-citronellic acid.

Preparation of Samples (3)

A number of solutions of 0.4% of commercially available racemie citronellic acid in ethyl acetate were prepared. Test Procedure (3)

Single separate filter papers were treated with either equal volumes of ethyl acetate (control - S) or a solution of 0.4% of racemie citronellic acid in ethyl acetate (treated - T). The control and treated filter papers were allowed to dry. Two control papers were placed in a Petri dish at the 12 and 6 o'clock positions. Two treated papers were placed in the Petri dish at the 9 and 3 o'clock positions. Adjacent pairs of control and treated papers were equidistant from each other. All papers were then moistened with distilled water. Six (6) such Petri dishes were so prepared. 100 termites (C. acinaciformis) were then added to the centre of four (4) of the dishes (Dishes 1 to 4) and 50 termites to the centre of the remaining two (Dishes 5 and 6). All dishes were then placed inside a darkened insectary at 27°C and 75% relative humidity. The number of termites present on the individual papers were recorded at two (2), four (4) and six (6) hours. The raw results are presented in the following Table 5.

Table 5

The attraction/repellence of a termite to a particular substance can be determined by the prefix index (PI):

PI = %TT - %TC

%TT + %TC where TT = termites present on treated paper TC = termites present on control paper

Once the PI has been determined, the attraction/repellence can be categorised according to the following scale:

Repellent: -1 <PI< -0.1 Neutral: -0.1 <PI< +0.1 Attractant: +0.1 <PI< +1

The PI for the results presented in Table 5 are as in Table 6.

Table 6

It will be seen from the above tabulated results that 0.4% solutions of racemie citronellic acid are consistently repellent towards C. acinaciformis.

The present invention should thus find use as an environment-friendly alternative to the use of synthetic chemical pesticides. Citronellic acid and its derivatives have already been . deemed safe for use in the food and pharmaceutical industries and its use as a pesticide and pest repellent should therefore readily find favour. A further advantage is that the less expensive, and more readily available, racemie mixture, is equally as effective as the more costly optical isomer. Yet further, the present invention should be easier to apply to an area to be protected as opposed to a physical pesticide barrier and can be used to pre-treat timber before that timber is used in any construction.

It will be appreciated that the above described embodiments are only exemplification of the various aspects of the present invention and that modifications and alterations can be made thereto without departing from the inventive concept as defined in the following claims.

Claims

1. A method for the control of pests, said method including the application of an effective amount of citronellic acid and/or one or more derivatives thereof to an area requiring said control.

2. A method as defined in Claim 1 wherein an effective amount of citronellic acid is applied to said area.

3. A method as defined in Claim 2 wherein an effective amount of racemie citronellic acid is applied to said area.

4. A method as defined in any one of Claims 1 to 3 wherein said area requiring control surrounds a structure which includes timber in its construction.

5. A method as defined in any one of Claims 1 to 3 wherein said area requiring control is a structure which includes timber in its construction.

6. A method as defined in any one of Claims 1 to 3 wherein said area requiring control is timber before said timber is used in a construction.

7. A pesticidal composition which is toxic to pests in a given area containing said pests and/or repels said pests from said area, said composition including an effective amount of citronellic acid and/or one or more derivatives thereof.

8. A pesticidal composition as defined in Claim 7 which comprises citronellic acid.

9. A composition as defined in Claim 8 wherein said citronellic acid is racemie citronellic acid.

10. A pesticidal composition as defined in any of Claims 7 to 9 which includes a carrier, diluent or adjuvant.

11. A method as defined in any one of Claims 1 to 6 wherein said pests are subterranean termites.

12. A method as defined in Claim 11 wherein said termites are Coptotermes acinaciformis.