GB2563597A - Improved insecticide formulations - Google Patents

Abstract

An insecticide formulation comprising i) a naturally occurring pyrethrin (e.g. pyrethrins I and II, jasmolin I and II and cinerin I and II) and ii) an unsaturated fatty acid or fatty acid mixture containing an average of from 16 to 24 carbon atoms (C16-C24) and/or their alkali metal salts wherein the unsaturated fatty acids are derived from natural sources and wherein the ratio of the weight of unsaturated fatty acid and/or alkali metal salt thereof to the weight of natural pyrethrin is from 3:1 to 20:1. Preferably, the unsaturated acid is a mixture of unsaturated acids. Preferably, the formulation has a pH below 7, most preferably, between 3.5 and 7. Preferably, the ratio of fatty acid(s) and/or specified derivatives to pyrethrin is from 3:1 to 10:1. Preferably, the unsaturated fatty acids are unsaturated linear acids. Most preferably, the fatty acid composition comprises oleic acid and linoleic acid.

Description

IMPROVED INSECTICIDE FORMULATIONS

The present invention relates to improved insecticide formulations and their use.

The pyrethrum family has been known for many years as providing useful insecticides. Naturally occurring pyrethroids known as pyrethrins can be obtained from Chrysanthemum plants and other daisies. There are also a wide range of synthetic pyrethroids. Generally speaking the synthetic pyrethroids are more potent insecticides than the naturally occurring pyrethrins. Furthermore they tend to be more stable particularly on exposure to ultra-violet light. This combination of properties can have the damaging effect that after application to a crop because of infestation of a particular insect the synthetic pyrethroid may linger around and can be subsequently detrimental to beneficial insects such as bees. Natural pyrethrins are more readily degraded upon exposure to ultra violet light.

It would therefore be useful if the insecticidal potency of a natural pyrethrin could be increased to be comparable or superior to that of the synthetic pyrethroids.

It has been proposed in United States Patents 4,904,645 and 5,047,424 that synthetic or natural pyrethroids may be combined with fatty acid salt materials. US 4,904,645 states that it provides an environmentally safe insecticide combination of natural products having an acceptable shelf life, low acceptable phytoxicity and low cost. The formulation it provides comprises an aqueous solution of pH 7.5 to 8.8 containing 30 to 50 parts of an aqueous solution comprising 50 percent by weight of a mixture of monocarboxylic acids and their alkali metal salts, the acid mixture comprising at least 70% oleic acid and its alkali metal salts, together with between 1.0 and 2.0 parts of a pyrethrum extract comprising about 20% of a mixture of insecticidally active substances selected from pyrethrum I, pyrethrum II, cinerin I, cinerin II, jasmolin I and jasmolin II; 3 to 20 parts of a low molecular weight 2-6 carbon atoms alcohol solvent for the pyrethrum and an antioxidant. The salts are produced by reaction with potassium hydroxide and the pH is controlled with hydrochloric acid and accordingly the formulations are not 100% organic materials and are slightly alkaline. The material is diluted with water so that on application to plants it provides 0.5 wt % of the acid mixture and 0.005 wt % of the pyrethrum extract.

The ratio of the acids and their salts to the pyrethrum is of the order of from 80:1 to 100:1. United States Patent 5,047,424 discloses that the compositions of US Patent 4,904,645 (resulting from application serial no. 148961) are relatively expensive and are susceptible to degradation during storage or use because of the presence of pyrethrums.

Other suggestions have been to use naturally occurring triglycerides and other essential oils (US 2005/0244445) in insecticide formulations in combination with pyrethrins.

However there remains a need to improve the potency of naturally occurring pyrethrins whilst retaining their ability to degrade when exposed to ultra violet light and additionally to provide an environmentally friendly all organic insecticidally active combination.

The present invention therefore provides an insecticide formulation comprising i) naturally occurring pyrethrins ii) an unsaturated fatty acid or fatty acid mixture containing on average from 16 to 24 carbon atoms and/or their alkali metal salts wherein the unsaturated fatty acids are derived from natural sources wherein the ratio of the weight of unsaturated fatty acid and/or alkali metal salt thereof to the weight of natural pyrethrin is from 3:1 to 20:1.

The unsaturated acids and their derivatives which are used in this invention are mono- and polyunsaturated carboxylic acids having an average of 16 to 24 carbon atoms, or their alkali metal salts. It is preferred to use mixtures of unsaturated acids having an average of 16 to 24 carbon atoms. In particular we prefer to use C16 to C18 average mono- or polyunsaturated acids or their alkali metal salts more preferably we use the acids to provide a formulation having a pH below 7 typically in the range 3 to 7 more typically 5 to 7. The preferred C16 to C24 acids and their mixtures are derived from the production of naturally occurring products such as sunflower oil, palm oil, olive oil, maize oil, canola oil, and other vegetable oils, soya chestnuts and horse chestnuts. They may also be obtained from animal fats. The acids may be obtained by extraction and they typically comprise mixtures of mono-or poly- unsaturated acids and where mixtures are used the average number of carbon atoms in the acid mixture should be in the C16 to C24 range. We prefer that the ratio of the weight of the unsaturated fatty acid or fatty acid mixture or derivative thereof to the weight of pyrethrin is from 3:1 to 10:1 more preferably from 3:1 to 8:1.

The C16 to C24 average mono- and polyunsaturated acids used in the invention are typically linear C16 to C24 mono- and polyunsaturated acids and thus have the formula RCOOH wherein R is a linear mono- or polyunsaturated hydrocarbon radical having from 16 to 24 carbons. Thus, the C16 to C24 mono- and polyunsaturated acids may be selected from one or more of palmitoleic acid (C16:1) sapienic acid (016:1), α-linolenic acid (C18:3), stearidonic acid (C18:4), eicosapentaenoic acid (C20:5), docosahexaenoic acid (C22:6), linoleic acid (C18:2), γ-linolenic acid (C18:3), dihomo-Y-linolenic acid (C20:3), arachidonic acid (C20:4), adrenic acid (022:4), palmitoleic acid (016:1), vaccenic acid (018:1), paullinic acid (020:1), oleic acid (018:1), elaidic acid (Ctrans-18:1), gondoic acid (020:1), erucic acid (022:1), nervonic acid (024:1), mead acid (020:3) and derivatives thereof.

The notation CM:N fatty (where M and N are integers), as used herein, means that the fatty acid comprises M carbon atoms and N double bonds. The N double bonds may be at any position (cis or trans configuration), although two double bonds are not usually adjacent (i.e. bonded to the same carbon atom). Thus, 018:0 (or simply 018) covers only octadecanoic acid (stearic acid) and 018:1 includes all fatty acids having 18 carbons and one double bond, such as oleic acid ((Z)-octadec-9-enoic acid), vaccenic acid ((E)-octadec-11-enoic acid).

We have found that in some instances the use of a mixture of unsaturated fatty acids having an average of 16 to 24 carbon atoms together with the naturally occurring pyrethrin provides a more potent insecticide than a comparable formulation containing a single unsaturated acid. Accordingly we prefer to use mixtures of unsaturated acids and/or their alkali metal salts

An alkali metal salt of an acid is typically a lithium, sodium, potassium or rubidium salt.

The preferred C16 to C24 mono- and polyunsaturated acid mixture is preferably predominantly oleic acid, together with linoleic acid optionally with minor amounts of other acids and/or alkali metal salts thereof.

Many nuts and fruits contain a mixture of unsaturated fatty acids and one preferred source of materials is Aesculus hippocastanum which is known to contain typically 350 g / Kg oleic and linoleic acids (Zalatonov et al). Other preferred sources are the nut (acorn) of the oak tree (Genus Quercus) and ground coffee beans (the seed of the coffee plant). By-products of olive oil production are another preferred source.

The acids may be obtained from triglycerides derived from the natural products. The triglycerides may be hydrolysed to release the fatty acids from the triglyceride ester and then purified typically by fractionation and/or distillation to obtain the fatty acids which can be used in this invention. A typical composition of a fatty acid mixture obtained from a byproduct of olive oil production comprises from 70 to 85 wt % oleic acid and 5 to 20 wt % linoleic acid with the balance being C14 to C20 acids.

In the use of the insecticide formulation of this invention the formulation is preferably applied to the particular crop as an aqueous solution or emulsion in an amount that delivers from 5 to 1000 g per hectare more preferably from 5 to 500 g per hectare of the unsaturated acid or acids and derivatives. We have found that the use of the acid or acids can also reduce the requirement of the amount of the expensive pyrethrin required for a particular performance by at least 50%. It may be necessary to dissolve the acids and/or derivatives thereof in a water soluble solvent such as propylene glycol.

The invention is useful with any naturally occurring pyrethrins including pyrethrin I, cinerin I, jasmolin I and pyrethrin II, cinerin II and jasmolin.

The effective treat rate will depend upon the insect that is to be targeted which may also depend upon the crop that is to be treated. Generally we found that the registered field rate is effective, but the invention may allow a reduction of this rate in some situations.

The preferred insecticide formulations of this invention are adapted for spraying onto crops and are typically aqueous emulsions or solutions of the C16 to C24 mono- or polyunsaturated acid or acids and/or alkali metal salts thereof and the pyrethrin and which may be separate solutions for sequential application or as a single formulation. We prefer that the C16 to C24 mono- or polyunsaturated acid or its alkali metal salt is water soluble. Preferred aqueous formulations for agricultural spraying contain from 5 to 500 g per hectare of the C16 to C24 mono- or poly unsaturated acid or its derivatives optionally together with a solubiliser to improve the solubility of the acid or acids in water with the balance being water. Other additives such as antioxidants and viscosity modifiers may be included as may emulsifiers if the aqueous formulation is an emulsion. Any other materials are preferably naturally occurring products or are derived therefrom. The amount of the formulation that should be employed depends upon the target but typically we have found that formulations that provide from 50 to 250 grams of the C16 to C24 carboxylic acid or acids or alkali metal salts thereof per hectare, preferably 75 to 150 grams per hectare are effective.

The invention can be used against a variety of insects including, but not limited to, the following families of mites:

Tetranychidae: Examples: Tetranychus urticae (two-spotted mite), T. pacificus (Pacific mite), T. mcdanieli (McDaniel mite), T. turkestani (strawberry mite), Panonychus ulni (European red mite), P. citri (citrus red mite), Oligonychus pratensis (Banks grass mite), O. punicae (avocado brown mite), Eutetranychus hicoriae (pecan leaf scorch mite), Byrobia praetiosa (clover mite).

Eriophyidae (rust and blister mites): Examples: Phyllocoptruta oleivora (citrus rust mite), Eriophyes sheldoni (citrus bud mite), E. erinea (walnut blister mite), Epitrimerus pyri (pear rust mite), Aculops lycopersici (tomato russet mite).

Tenuipalpidae: Examples: Brevipalpus lewisi (citrus flat mite), B. phoenicis (red and black flat mite), Dolichotetranychus floridanus (pineapple false spider mite).

Tarsenomidae: Examples: Steneotarsonemus bancrofti (sugarcane stalk mite), S. ananas (pineapple tarsenomid), S. pallidus (cyclamen Acarapis woodi (honeybee mite).

The invention can be used against the following families of sucking insects:

Aleyrodidae (whiteflies): Examples: Bemisia tabaci (sweetpotato whitefly), Trialeurodes vaporariorum (greenhouse whitefly), Siphoninus phillyreae (ash whitefly), Dialeurodes citrifolii (cloudywinged whitefly), Aleurocanthus woglumi (citrus blackfly). Aphids, including peach-potato aphid (Myzus persicae), cotton aphid (Aphis gossypii).

Nitidulidae: examples Meligethes aeneus (pollen beetle).

Psyllidae (psyllids): Examples: Psylla pyricol (pear psylla), Paratrioza cockerelli (potato/tomato psyllid).

In a further embodiment the invention can be used against leaf mining flies of the order Diptera and family Agromyzidae. Examples of these flies are Liriomyza complex (serpentine leafminers), Phytomyza syngenesiae (chrysanthemum leafminer), Agromyza frontella (alfalfa blotch leafminer), Ophiomyia phaseoli (bean fly). Diptera: mosquitoes, subfamily Anophelinae and subfamily Culicinae.

Other target pests include, but are not limited to, Thysanoptera (thrips), Hymenoptera (wasps), Hemiptera (bugs), Cicadellidae (leafhoppers), Membracidae (treehoppers), Coccidae (scales), Pseudococcidae (mealybugs), Diaspididae (scales), and Solenopsis (fire ants). The invention is also useful against mosquitos particularly in tropical and sub-tropical climates.

We have found that use of the materials of this invention in the ratios specified produces an insecticide formulation in which the naturally occurring pyrethrin is as potent as synthetic pyrethroids.

The invention is illustrated by reference to the following example in which the insecticide performance of mixtures of natural pyrethrins and acid mixtures obtained as a by-product from the pressing in olive oil production by fractionation and distillation was determined. The In vivo bioassay method used was based on I RAC method 011.

Example 1

In this Example the insecticide mixture was compared with a similar mixture containing a synthetic pyrethroid. Meligethes aeneus (pollen beetle) were collected from oilseed rape plants in Knebworth, Nr Stevenage, in the United Kingdom. A single concentration of technical grade natural pyrethrins that gave approximately 25% mortality (0.0003%, 3 ppm) dissolved in acetone (0.5 ml_) was tested both in the presence and in the absence of 0.001% of an acid mixture containing about 75% oleic acid and 12% linoleic acid with other C14 to C20 acids obtained as a biproduct of olive oil production (ratio of 1 part pyrethrins to 3.3 parts acid mixture). The materials were pipetted into glass vials and allowed to evaporate whilst the vials were rotated on a roller mixer to produce Mixture A. A single concentration of the synthetic pyrethrum Alpha-cypermethrin which also gave approximately 25% mortality (0.00003%, 0.3 ppm) dissolved in acetone (0.5 ml_) again in the presence or in the absence of the acid mixture (ratio of 1 part pyrethrum to 3.3 parts synergist) were pipetted into glass vials and allowed to evaporate whilst the vials were rotated on a roller mixer to produce Mixture B.

The pH of the acid containing formulations was about 5.0.

After evaporation was complete, approximately. 10 adult pollen beetle were placed in each vial. After 24 hrs at room temperature, mortality was assessed. The experiments were completed in duplicate.

The mortality was also compared with acetone alone, the two pyrethroids on their own and the acid mixture alone. All the results are shown in Figure 1 showing a significantly better performance for the Mixture A of the invention.

Example 2

Meligethes aeneus (pollen beetle) were collected from oilseed rape plants in Aston, Nr Stevenage, in the United Kingdom. A single concentration of technical grade naturally occurring pyrethrin (1 ppm) dissolved in acetone (0.5 ml_) both with and without 0.001% of the acid combination used in Example 1 were pipetted into glass vials. The formulation containing the acid had a pH of 5. The formulations were allowed to evaporate whilst the vials were rotated on a roller mixer.

After evaporation was complete, 10 adult pollen beetle were placed in each vial. After 24 hrs at room temperature, mortality was assessed. The experiment were completed in duplicate.

The results are shown in Figure 2.

Example 3

Meligethes aeneus (pollen beetle) were collected from oilseed rape plants in Aston, Nr Stevenage, in the United Kingdom. A single concentration of technical grade pyrethrin (3 ppm) dissolved in acetone (0.5 ml.) in the presence/absence of 0.001% oleic acid or 0.001% of the acid mixture used in Example 1 were pipetted into glass vials. The formulation containing the acid had a pH of 5. The formulations were allowed to evaporate whilst the vials were rotated on a roller mixer.

After evaporation was complete, 10 adult pollen beetle were placed in each vial. After 48 hrs at room temperature, mortality was assessed. The experiments were completed in triplicate.

The results are shown in Figure 3.

Claims (15)

1. An insecticide formulation comprising i. a naturally occurring pyrethrin ii. an unsaturated fatty acid or fatty acid mixture containing an average of from 16 to 24 carbon atoms and/or their alkali metal salts wherein the unsaturated fatty acids are derived from natural sources wherein the ratio of the weight of unsaturated fatty acid and/or the alkali metal salt thereof to the weight of natural pyrethrin is from 3:1 to 20:1.

2. An insecticide formulation of Claim 1 wherein the unsaturated acids and their derivatives are C16 to C24 mono- and polyunsaturated acids, or their alkali metal salts.

3. An insecticide formulation of Claim 1 or Claim 2 in which the unsaturated acids are a mixture of unsaturated acids having an average of 16 to 24 carbon atoms.

4. An insecticide formulation according to any of the preceding claims having a pH below 7.

5. An insecticide formulation according to Claim 4 in which the pH is in the range 3.5 to 7.

6. An insecticide formulation according to any of the preceding claims in which the ratio is from 3:1 to 10:1.

7. An insecticide formulation according to any of the preceding claims in which the C16 to C24 acids and their mixtures are derived from the production of naturally occurring products selected from natural oil products such as sunflower oil, palm oil, olive oil, maize oil, canola oil.

8. An insecticide formulation according to any of Claims 1 to 6 in which the C16 to C24 acids are derived from soya chestnuts and horse chestnuts.

9. An insect ide formulation according to any of Claims 1 to 6 in which the C16 to C24 acids are derived from animal fats.

10. An insecticide composition according to any of the preceding claims in which the C16 to C24 mono- and polyunsaturated acids are linear C16 to C24 mono- and polyunsaturated acid.

11. The insecticide formulation according to any of the preceding claims in which the C16 to C24 mono- and polyunsaturated acid is a mixture which is predominantly oleic acid, together with linoleic acid optionally with minor amounts of other acids and/or alkali metal salts thereof.

12. An insecticide formulation according to any of the preceding claims in which the pyrethrin is selected from pyrethrin I, cinerin I, jasmolin I and pyrethrin II, cinerin II and jasmolin.

13. An insecticide formulation according to any of the preceding claims comprising an aqueous emulsion or solution.

14. A process comprising applying an insecticide formulation according to Claim 13 to vegetation.

15. A process according to Claim 14 in which the formulation is applied in an amount that provides 5 to 500 g per hectare of the C16 to C24 average mono- or polyunsaturated acid or the alkali metal salts thereof.