WO2011006735A1 - Method for removing insects from the exposed surface of a body of water - Google Patents

Abstract

A method for removing an infestation of insects such as wasps from the exposed surface of an open body of water, such as a swimming pool, includes adding one or more surfactants, either bio or synthetic, to the water. The insects are either repelled by the surfactant, or are unable to float on the water surface, and therefore are trapped and drowned. Dead insect bodies can then be removed by filtering.

Description

METHOD FOR REMOVING INSECTS FROM THE EXPOSED SURFACE OF A

BODY OF WATER

FIELD OF THE INVENTION

The invention pertains to the field of insect control, more particularly the control of all species of wasps, or any member of the aculeate family Vespidae.

BACKGROUND TO THE INVENTION

All species of wasps can have serious negative effects on the quality of human life when they are gathered together in large numbers in a small area.

When found in a recreational area, such as a garden, these pests can be a source of annoyance purely due to their presence and the fact that they are capable of injecting poison. A sting from a wasp is poisonous because of the venom injected, and as a result, it can cause severe allergic reactions. Young children and the elderly are at higher risk.

When a wasp stings a person, the muscles that surround the wasp's venom sac inject venom into the body. Once the venom is injected, the person will experience a severe stinging feeling, followed by swelling, redness and itching.

After that, the person may notice a large red area on the skin where he or she was stung. In rare cases, a bacterial skin infection can also occur. In some cases, people who are allergic to the stings can suffer severe medical problems and death. Around 100 people die every year from wasp stings.

Some symptoms of an allergic reaction include, swelling of the throat, nausea, vomiting, low blood pressure, a rash all over the body and faintness. If any of these symptoms occur, the person should receive immediate medical attention. When a wasp stings someone who isn't allergic to its venom, the effect of the sting is usually minor. However, when a person receives multiple wasps stings, kidney failure, muscle breakdown and other problems can occur. Major problems can also occur in people who are not allergic to wasp stings, depending on where they are stung. If someone is stung by a wasp in the mouth or throat, swelling can occur that can obstruct the airway and make it difficult to breathe. In addition to where a person is stung, several other factors determine how severely the sting will affect the person, such as how many times the person is stung.

The biggest attraction to wasps is water as it is the essential raw material required to build / expand their nests. Wasps need water and lots of it so any recreational area with a swimming pool, pond or water feature of any description will attract large numbers of wasps in the summer. This large presence of wasps will always prevent the use and enjoyment of the swimming pool and recreational areas. The method used by wasps to collect water involves landing and floating on the surface of the water. This is possible because of their relative light weight and the surface tension properties of the water. Wasps cause the elastic surface of the water to bend but not break under their weight. Before landing wasps will test the surface tension of water by touching it lightly while hovering over it. Attempts to control, eradicate or repel insects such as wasps have been disclosed in the art.

Thus, for example, Australian patent application AU 199944477 (Midgeekill Holdings Pty Ltd) discloses an apparatus for killing flying insects including a container, means for attracting the insects into the container and a liquid in the container for drowning the insects. The liquid may include a surfactant.

United States patent US 6463693 (Weisner) discloses an insect trap having a receptacle with a rear wall the top edge of which is thin. The trap is placed on a windowsill so the thin top edge of the rear wall lies flush against the window, providing a substantially smooth transition between the rear wall and the window. The receptacle is partially filled with a mixture of water and surfactant. In use, insects flying down the window travel over the thin top edge of the rear wall and continue down and fall into the water and drown.

United States patent US 6209256 (Brittin et al.) discloses a trap for attracting and killing insects utilizing carbon dioxide as the attractant. The carbon dioxide is either generated, or dispersed directly into, a trapping media. This supply of carbon dioxide bubbles through the trapping media to the surface where it diffuses into the atmosphere. Subsequently, the insects are attracted directly to the trapping media, the site of the attractant's emission, where the insect subsequently lands. The trapping media then effectuates the demise of the insect by drowning the insect or by permanently affixing the insect to the trapping media.

United States patent US 5836104 (Epps) discloses a passive, environmentally friendly apparatus and method for exterminating flying insects, particularly horseflies, without the use of chemical attractants or baits. A transparent deflector deflects the flying insects into a trap for extermination. A plurality of opaque targets are positioned about the deflector and trap so as to direct the flying insects into the deflector.

Finally, we are aware of United States patent US 5311696 (Gauthier et al.) which discloses a device for attracting and killing fleas and other insects and bugs, having a light for attracting the insects and a shallow reservoir of soapy water which the insects fall into causing them to drown.

None of these proposals addresses the problem of controlling and eradicating any infestation of insects from the exposed surface of an open body of water, which is the problem to which the present invention is directed. Methods of controlling wasps involving the use of pesticides, which can be highly dangerous to both humans and animals, are clearly unsuitable for use with bodies of water with which humans or animals may come into contact.

There is therefore a real need to provide an effective method of controlling wasps from the exposed surface of an open body of water, which is both safe in the environment and also non-toxic to humans, animals and fish.

SUMMARY OF THE INVENTION

According to the invention there is provided a method for removing insects from the exposed surface of an open body of water, without the application of a pesticide, the method including the step of adding a surfactant to said water, thereby to cause insects alighting on said surface to drown in the body of water. By use of this method, the insects are either repelled by the surfactant, or are trapped on the water surface, and therefore are drowned.

The present invention provides a method of controlling or eradicating insects such as wasps from swimming pools, and indeed any outdoor areas to which they may be attracted. The method does not require the use of any pesticides which are nearly always highly toxic to humans and also bad for the environment. The method of the invention is environmentally friendly and totally safe to humans, animals and fish. The method is especially applicable to insects which are members of the order Hymenoptera, most especially from the aculeate family Vespidae (wasps).

The present invention provides a method to control wasps which involves treating the water by introducing a surfactant or a combination of surfactants, dispensed either in liquid, powder, tablet or raw natural bio form into the water in order to reduce the surface tension between the two mediums, air and water.

After the introduction of the correct quantity and type of surfactant, wasps will still be attracted to the treated water but they will be prevented from collecting the water due to the now insufficient surface tension. Some will then simply fly away and find another source of water but most will still try to land on the surface only to then be trapped and drowned in the treated water.

We have found that after just a few days of treating the water, a previously infested area will be almost completely free of wasps.

The method preferably further comprises subsequently circulating water from said body of water through a filter to remove insect bodies therefrom.

The body of water is an open body of water, that is a body of water whose water/air surface is exposed to the atmospheric environment. The body of water is, for example, a pool or pond. However, the invention is particularly advantageous where the body of water is a swimming pool, wherein the body of water may comprise a chlorine-containing disinfectant compound, usually a source of hypochlorous acid, such as sodium hypochlorite. In this event, the surfactant is preferably substantially inert to the chlorine-containing compound.

The surfactant may be in the form of tablets, liquid or powder composed of a surfactant or a combination of surfactants. In any event, the surfactant is ideally nontoxic to humans. A low-foaming surfactant is preferred. The surfactant may be selected from anionic, nonionic, cationic, amphoteric and natural bio-surfactants.

As the invention pertains to treating the surface of the water rather than the entire body of water, preference will be given to surfactants capable of forming a molecular monolayer across the entire surface of the body of water to be treated. Surfactant molecules often organize themselves into 3-dimensional spheres called micelles, which have, for example, a hydrocarbon core and sulphate groups around the outer surface. However, some surfactants can also form other structures. Rather than forming a sphere, some surfactants can coat the surface of the water to form a layer one molecule thick, a molecular monolayer. It is these surfactants which are therefore most preferred.

Thus, it is preferred that, in use, the surfactant stays close to the air/water interface. Surfactants which would readily disperse throughout the bulk of the water would require higher dosages. The readily dispersed surfactant may need to be added at an amount of between 1 mg and 5 mg per litre of water. Even a small size swimming pool contains at least 125,000 litres of water and an Olympic size pool can have around 2,500,000 litres. The quantity of soluble surfactant required needs to be calculated in relation to the volume of water to be treated so we found that even with the strongest soluble surfactants, those having very low dilution rates, this still meant having to add at least 45 litres to even a small pool. This may be considered too costly in terms of manufacturing, transportation and storage costs etc..

It is therefore preferred that the surfactant has a low water-solubility. More hydrophobic surfactants are less soluble and would at first sight be more attractive because the amount required can be calculated in relation to the surface area rather than the total volume of water in the pool, meaning that a lot less would need to be added to achieve the same reduction in surface tension. However, because low solubility surfactants tend to be oil-based, it is found that within a very short time they start to leave scum marks around the walls at the edge of the pool, which is both unsightly and difficult to clean.

Furthermore, while anionic surfactants are particularly effective at reducing the surface tension by the amount required, they react in water with the positively charged water hardness ions (calcium and magnesium), which leads to partial deactivation. The more calcium and magnesium molecules in the water, the more anionic surfactants suffer from deactivation.

It has therefore been an objective of this invention, to formulate a surfactant composition which is less sensitive to the hardness of the water and also is not so oily as to leave such scum marks but includes surfactants which stay close to the air/water interface.

The surfactant composition according to the invention preferably comprises a mixture of an anionic surfactant and a further surfactant. In one embodiment, the surfactant composition according to the invention comprises a mixture of an anionic surfactant and a nonionic surfactant. Nonionic surfactants do not have an electrical charge, which makes them resistant to water hardness deactivation. A combination of anionic and nonionic surfactants would be more effective than the use of the anionic surfactant alone, in treating water in countries, such as southern Mediterranean countries, where the water is generally much harder.

Preferred nonionic surfactants may be selected from ethoxylated aliphatic alcohol, polyoxyethylene surfactants, carboxylic esters, polyethylene glycol esters, anhydrosorbitol ester and its ethoxylated derivatives, glycol esters of fatty acids, carboxylic amides, monoalkanolamine condensates, and polyoxyethylene fatty acid amides.

In a preferred embodiment, the surfactant or combination of surfactants comprises one or more natural bio-surfactants. Preferred natural bio-surfactants may be selected from soapnuts, soapnut powder, soapnut liquid, palm oil, coconut oil or any other natural substance possessing surfactant qualities. A preferred surfactant is derived from non-petrochemical sources and is, for example, saponin, which may be derived from soap nuts. We have found that a particularly advantageous natural surfactant is the plant-based surfactant extracted from fruit pericarps of Sapindus mukorossi, liquid soap nut detergent. The mass of soap nut liquid required in 1 litre of water to reduce the surface tension by the required amount is comparable to the mass of sodium dodecylsulfate solution required to achieve the same effect. The advantages of soap nuts compared to manufactured surfactants are clear. Soap nuts are completely natural, totally biodegradable and harmless to humans and animals. Furthermore, they have extremely low foaming qualities so, unlike petroleum based surfactants or other natural oil based surfactants they leave no greasy residue. They are a completely green product. However, depending on different conditions such as the hardness of the water to be treated and the method of application, it may not always be possible to use a completely green bio surfactant. In another embodiment, the surfactant composition according to the invention preferably comprises a mixture of anionic and amphoteric surfactants. Ideally the anionic surfactant is the major surfactant. The composition preferably also contains a cationic surfactant to render the composition less soluble. Thus, according to a preferred aspect of this invention, an aqueous based surfactant composition for controlling and eradicating any infestation of insects from the exposed surface of an open body of water, without the application of a pesticide, includes a major amount of an anionic surfactant, a lesser amount of a amphoteric surfactant and a minor amount of a cationic surfactant.

A preferred class of anionic surfactant is an alkoxylated alkali metal fatty acid sulphate, such as ethoxylated sodium lauryl sulphate (sodium laureth sulphate). Other preferred anionic surfactants may be selected from carboxylates, sulphonates, petroleum sulphonates, alkylbenzenesulphonates, naphthalenesulphonates, olefin sulphonates, alkyl sulphates, sulphates, sulphated natural oils & fats, sulphated esters, sulphated alkanolamides, alkylphenols, ethoxylated and sulphated compounds.

Preferred amphoteric surfactants may be selected from N-coco 3-aminopropionic acid/ sodium salt, N-tallow 3 -iminodipropionate, disodium salt

N-carboxymethyl N dimethyl N-9 octadecenyl ammonium hydroxide, and N- cocoamidethyl N hydroxyethylglycine, sodium salt. A preferred amphoteric surfactant is a betaine, such as cocamidopropyl betaine.

Preferred cationic surfactants may be selected from quaternary ammonium salts, amines with amide linkages, polyoxyethylene alkyl and alicyclic amines, N, N, N', N' tetrakis substituted ethylenediamines, and 2- alkyl 1- hydroxethyl 2-imidazolines. A suitable example is a fatty acid quaternary ammonium compound such as guar hydroxypropyltrimonium chloride.

The composition preferably also includes one or more ingredients selected from surface dispersal agents, semi-solid hydrocarbons, emulsifiers, humectants, sequestrants, buffers, preservatives and anti-foam agents.

The surface dispersal agent ensures that the surfactant mix spreads over the whole surface of the pool. A suitable surface dispersal agent is sunflower seed oil.

The semi-solid hydrocarbon, such as petrolatum, helps to keep the surfactant mix closer to the surface.

The emulsifier prevents the composition from separating during storage. In particular, the emulsifier acts as a stabiliser helping the surface dispersal agent to stay dispersed within the composition. A suitable emulsifier is a fatty acid such as lauric acid.

The humectant prevents the composition from drying out on storage. A suitable humectant is glycerin.

The anti-foaming agent, such as a silicone anti-foaming agent, is included to protect the filtration equipment of the pool and also to keep the surface clear for visiting insects to land on easily.

The sequestrant, such as disodium EDTA, is included to reduce the risk of spoilage of the composition by polyvalent metal ion catalysis.

The buffer, such as a weak acid or base, is included to ensure that the treated pool water retains a suitable pH for use, typically between 7.0 and 7.6. Where the natural pH of the pool water is higher than desired, a suitable buffer is citric acid. The composition preferably also includes a preservative, such as sodium benzoate.

A preferred surfactant composition comprises (by weight): anionic surfactant 10% to 20%

amphoteric surfactant 3% to 5%

surface dispersal agent 1 % to 4%

semi-solid hydrocarbon 0.5% to 3%

emulsifier 0.5% to 3%

humectant 0.25% to 2%

cationic surfactant 0.25% to 2%

sequestrant 0.1 to 1 %

pH regulator 0.025 to 0.2%

preservative 0.02 to 1.5%

anti-foam 0.5 to 1 %

water balance to 100%

All ingredients of the composition should be of such identity and quality as to represent no risk to users of the pool and preferably are of at least food grade quality.

Furthermore, the ingredients of the composition should not affect the pool equipment, nor interfere with the efficient functioning of the pool chemicals, should be clear and odourless and should not leave residue deposits on the walls of the pool.

Pesticides are absent from the composition. Usually, colouring agents such as dyes and pigments will be absent from the composition. Usually, fragrancing agents will be absent from the compositions. Water-insoluble solid materials will usually be absent from the compositions, to reduce the risk of sediment forming in the pool.

In use, the surfactant may be added to the body of water by spraying or pouring a solution thereof onto the exposed surface. For example, a small amount of the composition is pre-diluted with water to a dilution of from 1 ,000:1 to 5,000:1 in a suitably sized container and then thrown over the surface of a swimming pool at a composition dosage level of from 0.1 to 0.5 ml per square metre of pool surface.

This treatment may be repeated from time to time, say from at least once per day up to once per week, until any insect infestation of the pool is substantially eradicated. Alternatively, especially where the body of water is a swimming pool, besides spraying or pouring, the surfactant may also or alternatively be added to water in the circulation system. In one possible embodiment, where the body of water is a swimming pool having a chlorine-containing disinfectant compound in the water, the surfactant may be added together with the chlorine-containing compound. To this end, the invention may provide a composition for adding to the water of a swimming pool, the composition comprising a mixture of suitable quantities of the surfactant and a chlorine-containing disinfectant compound, such mixture to be dispensed in either tablet, liquid or powder form.

The invention will now be illustrated, purely by way of example, with reference to the following Example.

Example

The following surfactant composition was prepared (percent by weight): anionic surfactant Sodium laureth sulphate 12.00 amphoteric surfactant Cocamidopropyl betaine 3.00 surface dispersal agent Sunflower seed oil 1.75 semi-solid hydrocarbon Petrolactam 1.25 emulsifier Laurie acid 1.25 humectant Glycerine 1.00 cationic surfactant Guar hydroxypropyltrimonium chloride 1.00 sequestrant Disodium EDTA 0.50 buffer (pH regulator) Citric acid 0.09 preservative Sodium benzoate 0.07 silicone anti-foam Dow Corning® Antifoam C 1.00

Water to 100.00

10 ml of this composition was pre-diluted with water in a 25 litre bucket and thrown over the surface of a chlorinated swimming pool having a surface area of 9.0 m x 4.5 m ( a dosage level of about 0.25 ml/m²). The pool was located in an environment equivalent to the climate of Southern Spain in mid-summer. This application was repeated every 3 days and was found to reduce the wasp infestation numbers by 90%.

Claims

1. A method for controlling and eradicating any infestation of insects from the exposed surface of an open body of water, without the application of a pesticide, the method including the step of adding a surfactant or a combination of surfactants to said water, thereby to cause insects alighting on said surface to be trapped and drown in the body of water.

2. The method according to claim 1 , further comprising subsequently circulating water from said body of water through a filter to remove dead insect bodies therefrom.

3. The method according to claim 1 or 2, wherein said body of water is a swimming pool.

4. The method according to claim 3, wherein said body of water comprises a chlorine-containing disinfectant compound.

5. The method according to claim 4, wherein said surfactant is substantially inert to said chlorine-containing disinfectant compound.

6. The method according to any preceding claim, wherein said surfactant is nontoxic to humans.

7. The method according to any preceding claim, wherein said combination of surfactants is a composition including a major amount of an anionic surfactant and a lesser amount of an amphoteric surfactant.

8. The method according to any preceding claim, wherein said composition further includes a cationic surfactant.

9. The method according to claim 7 or 8, wherein said composition further includes one or more ingredients selected from surface dispersal agents, semi-solid hydrocarbons, emulsifiers, humectants, sequestrants, buffers, preservatives and anti- foam agents.

10. A method according to any preceding claim, wherein the surfactant or combination of surfactants comprises one or more natural bio-surfactants.

11. The method according to any preceding claim, wherein the insect is a member of the order Hymenoptera, especially from the aculeate family Vespidae (wasps).

12. The method according to any preceding claim, wherein the surfactant is added at an amount of between 1 mg and 5 mg per litre of water.

13. The method according to any preceding claim, wherein the surfactant is added to the body of water by spraying or pouring a solution thereof onto the exposed surface.

14. The method according to claim 3, wherein the surfactant is added to water in the circulation system of the swimming pool, with or without the addition of a chlorine- containing disinfectant compound.

15. An aqueous based surfactant composition for controlling and eradicating any infestation of insects from the exposed surface of an open body of water, without the application of a pesticide, the composition including a major amount of an anionic surfactant, a lesser amount of an amphoteric surfactant and a minor amount of a cationic surfactant.

16. The composition of claim 15, including, by weight, 10% to 20% of the anionic surfactant, 3% to 5% of the amphoteric surfactant and from 0.25% to 2% of the cationic surfactant.

17. The composition of claim 15 or 16, further including one or more ingredients selected from surface dispersal agents, semi-solid hydrocarbons, emulsifiers, humectants, sequestrants, buffers, preservatives and anti-foam agents.

18. The composition of any one of claims 15 to 17, further including a chlorine- containing disinfectant compound.