WO2021112758A1

WO2021112758A1 - A pesticide

Info

Publication number: WO2021112758A1
Application number: PCT/SG2019/050601
Authority: WO
Inventors: Revathi VIJEYAN; Ignacimuthu Savarimuthu; Michael Gabriel PAULRAJ
Original assignee: Future Gen Agriculture (S) Pte. Ltd.
Priority date: 2019-12-06
Filing date: 2019-12-06
Publication date: 2021-06-10
Also published as: SG11202105100RA

Abstract

The present invention provides a mosquito larvicide comprising: an active ingredient including at least seven organic oils including a plant seed oil that have an efficacy of at least 30% against Aedes aegypti mosquito larvae at a treatment period of up to 2 hours and a treatment concentration of 0.04v/v% in an aqueous mosquito breeding habitat; and an emulsifier that is adapted to form a homogeneous mixture comprising the active ingredient and the aqueous mosquito breeding habitat when the mosquito larvicide is added to the mosquito breeding habitat. The present invention also provides a method of producing the mosquito larvicide.

Description

A PESTICIDE

FIELD OF INVENTION

The present invention relates to a pesticide, particularly a larvicide.

BACKGROUND OF THE INVENTION

Mosquitoes are considered to be one of the most dangerous insects in the world capable of transmitting several lethal pathogens to humans. Approximately, 700,000 people are killed by malaria and nearly 30,000 people are killed by dengue and other mosquito-borne diseases annually. To date, nearly 3,500 species of mosquitoes have been identified throughout the world and nearly 100 species are acting as vectors and transmitting pathogens (Fang, 2010). Aedes, Anopheles and Calex are three important genera that are found in the world (Tandina, F., et. al., 2018, Mosquitoes (Diptera: Culicidae) and mosquito-borne diseases in Mali, West Africa. Parasites & Vectors, 11:467 (doi: 10.1186/sl3071-018-3045-8)).

Typically, chemical-based mosquito control techniques involving synthetic chemical pesticides, growth regulators, bacterial toxins, smokes and chemical repellents are practiced around the world. For example, synthetic pyrethrine, methoprene, pyriproxyfen and temephos are used to kill adult and larval mosquitoes.

These chemical methods enable the quick eradication of mosquitoes. However, chemical pesticides create several unwanted effects. Most were found to pollute the environment and adversely affect other nontarget organisms, such as human beings. Moreover, the use of chemical pesticides has led to the development of pesticide resistance in mosquitoes (Fouet, C., et. al., 2018, Human Interventions: Driving Forces of Mosquito Evolution. Trends in Parasitology, 34(2): 127-139; Marcombe, S., et al., 2011, Field efficacy of new larvicide products for control of multi-resistant Aedes aegypti populations in Martinique (French West Indies). Am J Trop Med Hyg., 84: 118-126). Alternative methods of mosquito control such as genetic control and sterile insect techniques are costly and difficult.

It is desirable to provide a pesticide that alleviates at least one of the problems mentioned above.

SUMMARY OF THE INVENTION

In a first form of the invention, there is provided a mosquito larvicide comprising: an active ingredient including at least seven organic oils including a plant seed oilthat has an efficacy of at least 30% against Aedes aegypti mosquito larvae at a treatment period of up to 2 hours and a treatment concentration of 0.04v/v% in an aqueous mosquito breeding habitat; and an emulsifier that is adapted to form a homogeneous mixture comprising the active ingredient in the aqueous mosquito breeding habitat when the mosquito larvicide is added to the mosquito breeding habitat.

In the specification, a mosquito breeding habitat is a body of liquid containing immature stages (egg, larvae and pupae) of any one or more of Aedes, Anopheles and Culex mosquitoes. Typical examples of the liquid include fresh water or contaminated (sewage) water.

In this specification, the term "organic oil" refers to a naturally occurring oil such as a botanical oil or a synthetic analog of the naturally-occurring oil.

The larvicide may be exclusively toxic to insects. Without being bound by theory, it is believed that the larvicide targets the nervous and endocrine systems of the mosquito larvae.

The larvicide may possess insect repellant properties.

The larvicide may impart repellant properties to the mosquito breeding habitat for at least 5 days after application. Suitably, the larvicide inparts repellant properties to the mosquito breeding habitat for at least 10 days after application.More suitably, the larvicide inparts repellant properties to the breeding habitat for at least 15 days after application.

The organic oils may be volatile under normal room temperature and pressure (NTP).

The active ingredient may contain exclusively botanical oils.

The plant seed oil may be Karanj oil.

The organic oils may be selected from Cinnamon oil, Clove oil, Pine oil, Camphor oil, Orange oil, Citronella oil, Vetiver oil, Mace oil, Wormwood oil, Karanj oil, Geranium oil, Lemon balm oil and Nochi oil.

The active ingredient may consist of a mixture of Cinnamon oil, Clove oil, Pine oil, Camphor oil, Orange rind oil, Citronella oil, Vetiver oil, Mace oil, Wormwood oil and Karanj oil.

One or more of Camphor oil, Pine oil and Citronella oil may be substituted with Geranium oil, Lemon balm oil and Nochi oil, respectively. Making this substitution does not substantially alter the efficacy of the larvicide.

The active ingredient may include 5-9v/v% Cinnamon oil. Suitably, the active ingredient includes about 7v/v% Cinnamon oil.

The active ingredient may include 2-6v/v% Clove oil. Suitably, the active ingredient includes about 4v/v% Clove oil.

The active ingredient may include 3-7v/v% Pine oil or Lemon balm oil. Suitably, the active ingredient includes about 5v/v% Pine oil or Lemon balm oil.

The active ingredient may include 3-7v/v% Camphor oil or Geranium oil. Suitably, the active ingredient includes about 5v/v% Camphor oil or Geranium oil. The active ingredient may include 3-7v/v% Orange rind oil. Suitably, the active ingredient includes about 5v/v% Orange rind oil.

The active ingredient may include 2-6v/v% Citronella oil or Nochi oil. Suitably, the active ingredient includes about 4v/v% Citronella oil or Nochi oil.

The active ingredient may include 2-6v/v% Vetiver oil. Suitably, the active ingredient includes about 4v/v% Vetiver oil.

The active ingredient may include 2-6v/v% Mace oil. Suitably, the active ingredient includes about 4v/v% Mace oil.

The active ingredient may include 2-6v/v% Wormwood oil. Suitably, the active ingredient includes about 4v/v% Wormwood oil.

Suitably, the v/v% amount of plant seed oil in the composition is selected such that the v/v% sum of the active ingredients and emulsifier total 100v/v%.

The active ingredient may include 20-60v/v% of Karanj oil. Suitably, the active ingredient includes about 40v/v% of Karanj oil.

The active ingredient may include 5-9v/v% Cinnamon oil, 2-6v/v% Clove oil, 3-7v/v% Pine oil or Lemon balm oil, 3-7v/v% Camphor oil or Geranium oil, 3-7v/v% Orange rind oil,2-6v/v% Citronella oil or Nochi oil, 2-6v/v% Vetiver oil, 2-6v/v% Mace oil, 2-6v/v% Wormwood oil, and 20-60v/v% of Karanj oil.

The larvicide may include 16-20v/v% emulsifier. Suitably, the larvicide includes about 18v/v% emulsifier.

The emulsifier may be a blend of anionic and non-ionic surfactants in aromatic hydrocarbon. Suitably, the emulsifier is DMA-NEA from Unitop Chemicals Pvt.Ltd.More suitably,the emulsifier includes dimethoate.

The larvicide may consist of 5-9v/v% Cinnamon oil, 2-6v/v% Clove oil, 3-7v/v% Pine oil, 3-7v/v% Camphor oil, 3-7v/v% Orange rind oil, 2- 6v/v% Citronella oil, 2-6v/v% Vetiver oil, 2-6v/v% Mace oil, 2-6v/v% Wormwood oil, 20-60v/v% of Karanj oil, with the remainder being an emulsifier such that the v/v% sum of the active ingredients and emulsifier total 100v/v%.

Suitably, the larvicide consists of the following components:

Table 1:Mosquito larvicide composition

The efficacy may be at least 30% against Aedes aegypti at a treatment time of 2 hours and a treatment concentration of 0.04v/v%.

The efficacy may be at least 30% against Anopheles _Stephensi at a treatment time of 2 hours and a treatment concentration of 0.04v/v%.

The efficacy may be at least 40% against Culex gainguefasciatus at a treatment time of 2 hours and a treatment concentration of 0.04v/v%. The treatment concentration may range from 0.01-0.20v/v%. Suitably, the treatment concentration ranges from 0.02-0.lv/v%. More suitably, the treatment concentration ranges from 0.04-0.08v/v%. Even more suitably, the treatment concentration is 0.04v/v%. Increasing the treatment concentration may achieve a predetermined efficacy in a reduced treatment time.

In a second form of the invention, there is provided a method of producing a mosquito larvicide as previously described, including: mixing at least seven organic oils, including a plant seed oil, to form an organic oil mixture; mixing a plant seed oil with the organic oil mixture to form an active ingredient mixture that has an efficacy of at least 30% against Aedes aegypti mosquito larvae at a treatment period of up to 2 hours and a treatment concentration of 0.04v/v% in an aqueous mosquito breeding habitat; and mixing the active ingredient mixture with an emulsifier to form the mosquito larvicide that is adapted to form a homogeneous mixture comprising the active ingredient and the aqueous mosquito breeding habitat when the mosquito larvicide is added to the mosquito breeding habitat.

Each of the mixing steps may occur at a mixing rate ranging from 100- 150 rpm. Suitably, each mixing step occurs at a mixing rate of 120 rpm.

Each of the mixing steps may occur for a time period ranging from 5- 20 minutes. Suitably, each mixing step occurs for a time period of 10 minutes.

DETAILED DESCRIPTION

One aspect of the mosquito larvicide as defined by the invention comprises an active ingredient including at least seven organic oils including a plant seed oil, and an emulsifier.

The larvicide directed towards any one or more of Aedes, Anopheles and Culex mosquito larvae and is toxic to insects only. The larvicide does not adversely inpact on the health of non-target organisms such as humans and animals.

An advantage of the larvicide is that it can effectively destroy mosquitoes at the larval stage in their breeding habitats before they can mature into adult mosquitoes and disperse. Another advantage is that the larvicide can be applied directly to a mosquito breeding habitat, which is typically a stagnant body of water,because it is a liquid formulation. The active ingredient comprises a combination of exclusively botanical oils consisting of Cinnamon oil, Clove oil, Pine oil, Camphor oil, Orange oil, Citronella oil, Vetiver oil, Mace oil and Wormwood oil, and a plant seed oil being Karanj oil.

It was discovered that the efficacy of the larvicide remained substantially similar when any one or more of Camphor oil, Pine oil and Citronella oil was substituted with Geranium oil, Lemon balm oil and Nochi oil, respectively.

The active ingredient in the larvicide comprises purely natural substances obtained from medicinal plants which are non-toxic to humans.

The larvicide further includes an emulsifier to form a homogeneous mixture when the larvicide is added to a mosquito breeding habitat. The emulsifier is a blend of anionic and non-ionic surfactants in aromatic hydrocarbon. A preferred emulsifier is DMA-NE from Unitop.

A synergistic effect was observed when the organic oils were combined in which the efficacy of the larvicide against each of Aedes,Anopheles and Calex mosquito larvae is greater than the efficacy of each individual oil in the larvicide up to a treatment time of 2 hours. For example, all individual oils used in the larvicide exhibited an efficacy of less than 10% against Aedesaegypti mosquito larvae at 2 hours (at 0.04v/v% concentration) when used individually,whereas the mosquito larvicide exhibited an efficacy of at least 40% against the same larvae.

It was also discovered that the larvicide also imparted repellant properties to the breeding habitat.

Without being bound by theory, it is believed that the synergistic effect is due to the specific combination of plant seed oil and the organic oils. The biomolecules in the active ingredient is also believed to reduce the likelihood of mosquitoes developing resistance against the larvicide. The mosquito larvicide was produced by:

(i) combining 7v/v% amount of Cinnamon oil, 4v/v% amount of Clove oil, 5v/v% amount of Pine oil, 5v/v% amount of Camphor oil, 5v/v% amount of Orange rind oil, 4v/v% amount of Citronella oil, 4v/v% amount of Vetiver oil, 4v/v% amount of Mace oil and 4v/v% amount of Wormwood oil to form an organic oil mixture;

(ii) mixing the organic oil mixture at a mixing rate of 120 rpm for 10 minutes;

(iii) adding 40v/v% of a plant seed oil, Karanj oil, to the organic oil mixture to form an active ingredient mixture;

(iv) mixing the active ingredient mixture at a mixing rate of 120 rpm for 10 minutes;

(v) adding an emulsifier, DMA-NE to the active ingredient mixture to form a mosquito larvicide mixture; and

(vi) mixing the mosquito larvicide mixture at a mixing rate of 120 rpm for 10 minutes.

Camphor oil, Pine oil and Citronella oil can be substituted with the same amounts of Geranium oil, Lemon balm oil and Nochi oil, respectively.

Example

Laboratory and field experiments were performed to assess the efficacy of the organic mosquito larvicide having the composition of Table 1 compared to the efficacy of its individual component oils, which is reproduced below.

Table 1: Organic mosquito larvicide composition

The efficacy of the larvicide was found to vary between different mosquito species. For example, Calex gaingaefasciatas was the most sensitive species to the formulation; the highest larval mortality was recorded in Calex gaingaefasciatas compared to Aedes aegypti and Anopheles _Stephensi under laboratory conditions. However, it was observed that the larvicide consistently exhibited enhanced efficacy against each of Aedes,Anopheles and Calex mosquito larvae at a fixed treatment time and concentration when compared to the efficacy of the individual oils in the larvicide. The efficacy results are set out in Tables 2-4.

It was observed that the larvicide would eradicate at least 30% of Aedes, Anopheles and Calex mosquito larvae at a time period of up to two hours which was not achievable by any of the individual oils in the larvicide.A general increase in efficacy against any one or more of Aed.es, Anopheles and Calex mosquito larvae was also observed when comparing the larvicide against the individual oils for treatment times up to 8 hours.

Table 2: Comparison of efficacy (%) between the larvicide and the individual oils against Aedes aegypti mosquito larvae at a treatment concentration of 0.04v/v%.

Values are Mean ± SD (Standard Deviation) (Replications=10;no.of larvae in each replication = 5)

It was observed that the individual oils exhibited no activity against Aedes aegypti mosquito larvae at a treatment time of 1 hour, whereas the larvicide exhibited a 10% efficacy under laboratory conditions and ~20% under field conditions at the same treatment time.

The efficacy of the larvicide increased to ~40% (laboratory conditions) and ~50% (field conditions) at a treatment time of 4 hours while the most effective individual oil (Citronella) only exhibited about ~8% efficacy. Greater than 85% efficacy was reached with an 8 hour treatment period for the larvicide whilst the most effective individual oil (Camphor oil) was only 72.1% for the same treatment period.

Table 3: Comparison of efficacy (%) between the larvicide and the individual oils against Anopheles _Stephensi mosquito larvae at a treatment concentration of 0.04v/v%.

It was observed that the individual oils exhibited no activity against Anopheles Stephensi mosquito larvae at a treatment time of 1 hour, except Citronella oil which exhibited an efficacy of about ~8v/v% whereas the larvicide exhibited a 15% efficacy under laboratory conditions. The efficacy of the larvicide increased to about ~70% (laboratory conditions) at 4 hours while the most effective individual oil (Citronella) only exhibited about ~50% efficacy. A ~90% efficacy was reached with an 8 hour treatment period for the larvicide. Only Cinnamon oil exhibited a similar efficacy for the same treatment period with the remaining oils having an efficacy less than 75v/v%.

Table 4: Comparison of efficacy (%) between the larvicide and the individual oils against Cnlex guinguefasciatus mosquito larvae at a treatment concentration of 0.04v/v%.

It was observed that only three individual oils exhibited an efficacy ranging from 2-4% against Culex guinqaefasciatus mosquito larvae at a treatment time of 1 hour, whereas the larvicide exhibited ~20% efficacy under laboratory conditions and ~40% under field conditions.

The efficacy of the larvicide increased to ~55% (laboratory conditions) and about 65% (field conditions) at a treatment time of 2 hours while the most effective individual oil (Cinnamon) only exhibited about 40% efficacy for the same treatment time.Greater than 90% efficacy was reached with an 8 hour treatment period for the larvicide under both laboratory and field conditions. Only Camphor and Karanj oil exhibited similar efficacy when used individually.

It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in any country.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e.to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

Claims

CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A mosquito larvicide comprising: an active ingredient including at least seven organic oils including a plant seed oil that have an efficacy of at least 30% against Aedes aegypti mosquito larvae at a treatment period of up to 2 hours and a treatment concentration of 0.04v/v% in an aqueous mosquito breeding habitat; and an emulsifier that is adapted to form a homogeneous mixture comprising the active ingredient and the aqueous mosquito breeding habitat when the mosquito larvicide is added to the mosquito breeding habitat.

2. The mosquito larvicide according to claim 1, wherein the active ingredient consists of botanical oils.

3. The mosquito larvicide according to either claim 1 or 2,wherein the organic oils are selected from Cinnamon oil, Clove oil, Pine oil, Camphor oil, Orange oil, Citronella oil, Vetiver oil, Mace oil, Wormwood oil, Karanj oil, Geranium oil, Lemon balm oil and Nochi oil.

4. The mosquito larvicide according to any one of the preceding claims, wherein the plant seed oil is Karanj oil.

5. The mosquito larvicide according to any one of the preceding claims,wherein the active ingredient comprises 5-9v/v% Cinnamon oil, 2-6v/v% Clove oil, 3-7v/v% Pine oil or Lemon balm oil, 3-7v/v% Camphor oil or Geranium oil, 3-7v/v% Orange rind oil, 2-6v/v% Citronella oil or Nochi oil, 2-6v/v% Vetiver oil, 2-6v/v% Mace oil, 2-6v/v% Wormwood oil, and 20-60v/v% of Karanj oil.

6. The mosquito larvicide according to any one of the preceding claims, including 16-20v/v% emulsifier.

7. The mosquito larvicide according to any one of the preceding claims,consisting of 5-9v/v% Cinnamon oil,2-6v/v% Clove oil, 3-7v/v% Pine oil or Lemon balm oil, 3-7v/v% Camphor oil or Geranium oil, 3- 7v/v% Orange rind oil, 2-6v/v% Citronella oil or Nochi oil, 2-6v/v% Vetiver oil, 2-6v/v% Mace oil, 2-6v/v% Wormwood oil, 20-60v/v% of Karanj oil, with the remainder being an emulsifier such that the v/v% sum of the active ingredients and emulsifier total 100v/v%.

8. The mosquito larvicide according to any one of the preceding claims, consisting of 7v/v% Cinnamon oil, 4v/v% Clove oil, 5v/v% Pine oil or Lemon balm oil, 5v/v% Camphor oil or Geranium oil, 5v/v% Orange rind oil, 4v/v% Citronella oil or Nochi oil, 4v/v% Vetiver oil, 4v/v% Mace oil, 4v/v% Wormwood oil, 40v/v% Karanj oil, and 18v/v% emulsifier.

9. The mosquito larvicide according to any one of the preceding claims, wherein the active ingredient consists of a mixture of Cinnamon oil,Clove oil,Pine oil,Camphor oil,Orange oil,Citronella oil, Vetiver oil, Mace oil, Wormwood oil and Karanj oil.

10. The mosquito larvicide according to any one of the preceding claims, consisting of 7v/v% Cinnamon oil, 4v/v% Clove oil, 5v/v% Pine oil, 5v/v% Camphor oil, 5v/v% Orange rind oil, 4v/v% Citronella oil, 4v/v% Vetiver oil, 4v/v% Mace oil, 4v/v% Wormwood oil, 40v/v% Karanj oil, and 18v/v% emulsifier.

11. The mosquito larvicide according to any one of the preceding claims, wherein the emulsifier is a blend of anionic and non-ionic surfactants in aromatic hydrocarbon.

12. The mosquito larvicide according to any one of the preceding claims, wherein the emulsifier includes dimethoate.

13. The mosquito larvicide according to any one of the preceding claims, wherein the larvicide inparts repellant properties to the mosquito breeding habitat for at least 5 days after application.

14. A method of producing a mosquito larvicide according to any one of claims 1 to 13, including: mixing at least seven organic oils, including a plant seed oil, to form an organic oil mixture; mixing a plant seed oil with the organic oil mixture to form an active ingredient mixture that has an efficacy of at least 30% against Aedes aegypti mosquito larvae at a treatment period of up to 2 hours and a treatment concentration of 0.04v/v% in an aqueous mosquito breeding habitat; and mixing the active ingredient mixture with an emulsifier to form the mosquito larvicide that is adapted to form a homogeneous mixture comprising the active ingredient and the aqueous mosquito breeding habitat when the mosquito larvicide is added to the mosquito breeding habitat.

15. The method according to claim 14,wherein each mixing step occurs at a mixing rate ranging from 100-150 rpm.

16. The method according to claim 15, each mixing step occurs at a mixing rate of 120 rpm.

17. The method according to any one of claims 14 to 16,wherein each mixing step occurs for a time period ranging from 5-20 minutes.

18. The method according to claim 17, wherein each mixing step occurs for a time period of 10 minutes.