GB1576352A

GB1576352A - Pesticidal composition

Info

Publication number: GB1576352A
Application number: GB10079/77A
Authority: GB
Original assignee: Boots Co PLC
Current assignee: Boots Co PLC
Priority date: 1977-03-10
Filing date: 1977-03-10
Publication date: 1980-10-08
Also published as: TR20038A

Description

(54) PESTICIDAL COMPOSITION (71) We, THE BOOTS COMPANY LIMITED, a British Company of 1 Thane Road West, Nottingham, NG2 3AA do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a new pesticide composition.

We have discovered that a mixture of the pesticides amitraz and Bacillus thuringiensis has valuable pesticidal properties and in its action is more effective than the use of these pesticides on their own. Amitraz has a wide range of insecticidal and acaricidal properties, having the chemical formula 1,5-di-(2,4-dimethylphenyl)- 3-methyl-1,3,5 -triazapenta-1,4-diene, as described in our British Patent 1,327,935. The biological organism Bacillus thuringiensis is also a well-known pesticide which has been widely used on crops.

Accordingly, in one of its aspects, the invention provides a pesticidal composition comprising amitraz and Bacillus thuringiensis.

This mixture of pesticides is active against a wide range of insects and acarids. Amongst the insects it can be used to control there are included the cabbage looper (Trichoplusia ni), fall armyworm (Spodoptera frugiperda), southern armyworm Spodoptera eridania), tomato pinworm (Keiferia lycopersicella), diamond back month (Plutella maculipennis), bollworm (Heliothis zea) and aphids such as the green peach aphid (Myzus persicae). Acarid species such as, for example, the two spotted spider mite (Tetranychus urticae) and citrus red mite (Panonychus citri) can also be controlled by means of the mixtures. These pests attack important crops and in doing so cause great economic damage.

One of the main requirements for an effective pesticide is that it should give a broad spectrum of pest control on the crops which it will be applied to. The aim is to reduce, or eliminate, as many as possible of the pest species attacking the crop by application of a single pesticide. Moreover one wants to use a material which is not only effective against the pests but can also be employed at a low chemical rate for cheapness and in order to avoid possible undesirable effects to the environment.

When used individually both of the ingredients are active in their own right, but we have discovered that there are advantages in putting the two pesticides together and applying a mixture to the infested crop. For example, amitraz is especially effective as an ovicide against many lepidopterous species whereas Bacillus thuringiensis can only kill larvae. The combined action of these two pesticides gives excellent control of a wide spectrum of pests in different stages of development. We have also observed a surprising co-operative action between the two active components in that amitraz appears to make some larvae more susceptible to control by Bacillus thuringiensis, the quantities of which can be lowered correspondingly. The effect is more than an additive one and can be described as synergistic.

The active components in the composition of the invention are preferably used in the ratio of 1 to 20 parts by weight of amitraz to 1 part by weight of Bacillus thuringiensis, more especially in the ratio of 2 to 10 parts by weight of amitraz to 1 part by weight of Bacillus thuringiensis. If desired one or more additional pesticides can be added to the pesticidal composition of the invention, for example a further insecticide or acaricide.

The compositions of the invention include not only compositions in a suitable form for direct application to a crop but also concentrated primary compositions which may be supplied to the user and which require dilution with a suitable quantity of water or other diluent before application. Included in the former type of composition are, for example, aqueous dispersions or aqueous emulsions prepared either by diluting a dispersible powder primary composition or by tank mixing the two active components. Tank-mixing, prior to spraying the crop, is in many cases the most convenient way of preparing the compositions.

Both amitraz and Bacillus thuringiensis are available as convenient formulations and can be added in turn to water in the tank, ensuring that both active components are thoroughly dispersed. Thus the compositions of the invention may be prepared by sequentially mixing amitraz and Bacillus thuringiensis in water to provide a pesticidal composition for spraying crops.

As mentioned above the composition of the invention can also be in concentrated form and we particularly envisage dusting powders and dispersible powders. A dusting powder comprises the active components intimately mixed with a solid powdery diluent, for example kaolin.

A dispersible powder comprises the active ingredients in finely divided form in association with one or more dispersing agents so that a stable aqueous dispersion of the active components is formed on mixing the powder with water. A finely divided inert solid diluent such as kaolin or celite is generally incorporated in the dispersible powder.

The total concentration of the active components (when used as the sole active materials) in a composition of the invention for direct application to a crop is generally within the range of 0.001 to 10 per cent by weight of the composition although when aerial spraying of the crop is contemplated compositions having a higher concentration, for example, in the range of from 0.01 to 30 per cent by weight may be chosen in preference. In a concentrated primary composition the concentration of the active components may vary widely and can be, for example, from 5 to 95 per cent by weight of the composition.

As a further aspect, the invention provides a method for combating pests which comprises applying a composition of the invention to the locus of the pests, that is, to the pests or their habitat. In particular the invention includes a method for protecting plants from insects and acarids by the application of a composition of the invention to the plants. A wide variety of crops including top fruit, citrus, cotton, vegetables and tomatoes can be protected by treatment with a pesticidal composition of the invention, applied most conveniently as a foliar spray at a rate of preferably from 1 to 5 kilograms per hectare, especially from 1.5 to 4 kilograms per hectare.

Amongst the crops which are most effectively treated with the compositions of the invention is cotton.

It is often best to treat this crop in the early stages of growth and to follow with further treatments at a later stage.

The invention is illustrated by the following Examples.

EXAMPLE This Example illustrates the activity of the composition of the invention against larvae of the diamond back moth (Plutella maculipennis).

Ten larvae were placed in a tube together with a square inch of cabbage leaf which had been dipped in the test solution and allowed to dry. After twenty-four hours untreated cabbage was added for food and after a further twenty-four hours assessment was made of the mortality of the larvae.

Two replicates were carried out for each test compound and test solutions of varying concentrations employed so that an LD50 value could be calculated.

The test solutions were prepared from aqueous dispersions of amitraz and Bacillus thuringiensis and were mixed to give varying ratios of the two active components (1) Ratio Percentage amitraz Bacillus thuringiensis mortality (ppm > 0 (ppm) 100 92 80 80 (1:1) 92 200 50 (4.1) 95 320 20 (16:1) 81 400 0 16:1) 14 (2) Ratio Percentage Percentage mortality (ppm > 80 40 (2:1) 78 872g 200 25 (8:1) 81 400 : 0 14 The table shows that Bacillus thuringiensis is very effective at controlling Plutella maculipennis at rates of 100 ppm. Amitraz, on the other hand, at rates of 400 ppm. is virtually without effect. When Bacillus and amitraz are mixed at a number of ratios it is clear that the addition of amitraz maintains the high level of larval mortality despite reductions in the concentration of Bacillus thuringiensis. This is surprising in view of the lack of activity of amitraz alone and demonstrates a potentiation or synergistic effect.

WHAT WE CLAIM IS 1. A pesticidal composition which comprises amitraz and Bacillus thuringiensis.

2. A pesticidal composition according to claim 1 which comprises 1 to 20 parts by weight of amitraz to 1 part by weight of Bacillus thuringiensis.

3. A pesticidal composition according to either of claims 1 and 2 in which the total quantity of active components is in the range of from 0.001 to 10 per cent by weight of the composition.

4. A concentrated pesticidal composition according to either of claims 1 and 2 in which the total quantity of active components is in the range of 5 to 95 per cent by weight of the composition.

5. A method for combating pests which comprises applying a composition according to any of claims 1 to 4 to the locus of the pest.

6. A method according to claim 5 for protecting plants from insects and acarids by the application of a composition according to any of claims 1 to 4 to the plants.

7. A method according to claim 6 in which the plants are a cotton crop.

8. A method according to claim 4 substantially as described in the Example.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

(2) Ratio Percentage Percentage mortality (ppm >

80 40 (2:1) 78 872g

200 25 (8:1) 81

400 : 0 14 The table shows that Bacillus thuringiensis is very effective at controlling Plutella maculipennis at rates of 100 ppm. Amitraz, on the other hand, at rates of 400 ppm. is virtually without effect. When Bacillus and amitraz are mixed at a number of ratios it is clear that the addition of amitraz maintains the high level of larval mortality despite reductions in the concentration of Bacillus thuringiensis. This is surprising in view of the lack of activity of amitraz alone and demonstrates a potentiation or synergistic effect.

WHAT WE CLAIM IS 1. A pesticidal composition which comprises amitraz and Bacillus thuringiensis.
2. A pesticidal composition according to claim 1 which comprises 1 to 20 parts by weight of amitraz to 1 part by weight of Bacillus thuringiensis.
3. A pesticidal composition according to either of claims 1 and 2 in which the total quantity of active components is in the range of from 0.001 to 10 per cent by weight of the composition.
4. A concentrated pesticidal composition according to either of claims 1 and 2 in which the total quantity of active components is in the range of 5 to 95 per cent by weight of the composition.
5. A method for combating pests which comprises applying a composition according to any of claims 1 to 4 to the locus of the pest.
6. A method according to claim 5 for protecting plants from insects and acarids by the application of a composition according to any of claims 1 to 4 to the plants.
7. A method according to claim 6 in which the plants are a cotton crop.
8. A method according to claim 4 substantially as described in the Example.