Mosquito larva killing composition

Abstract

The invention relates to the use of a composition for killing mosquito larvae, said composition comprising:-at least one oil having a kinematic viscosity at 40 DEG C of 1.5 mm2 / s to 4 mm2 / s, a flash point of 80 DEG C to 150 DEG C and a pour point of-80 DEG C to-50 DEG C, and a boiling point of 200 DEG C to 350 DEG C, the amount of said oil being greater than 94% by weight, relative to the total weight of the composition; and-at least one surfactant selected from amphiphilic surfactants wherein the amount of said surfactant is from 0.25% to 6% by weight relative to the total weight of the composition.

Description

Technical Field

[0001] The present invention relates to a composition for killing mosquito larvae and its use for killing mosquito larvae. Background Art

[0002] Mosquitoes are common insects in the family Culicidae. Mosquitoes go through four stages in their life cycle: egg, larva, pupa, and adult or imago. Adult females lay eggs in stagnant water, which can be salt marshes, lakes, puddles, natural reservoirs on plants, or artificial water containers such as plastic buckets. The first three stages are aquatic, and within the last 5 - 14 days, depending on the species and environmental temperature, the eggs hatch into larvae and then turn into pupae. Adult mosquitoes hatch from the pupae and float on the water surface. The adults survive for 4 - 8 weeks. The larvae breathe through spiracles located on the eighth abdominal segment or through a siphon, and thus must come to the water surface frequently.

[0003] Mosquitoes are vectors that transmit pathogenic viruses and parasites between humans without themselves being infected with the disease. Some of them feed on humans and are vectors of malaria, and mosquito control is a very effective way to reduce the incidence of malaria. The main mosquito - transmitted diseases are the viral diseases yellow fever, dengue fever, and chikungunya, mainly transmitted by Aedes aegypti. It is estimated that mosquitoes transmit diseases to more than 700 million people in Africa, South America, Central America, Mexico, and most of Asia every year, resulting in millions of deaths. At least 2 million people die from these diseases every year.

[0004] There are many methods for mosquito control. Depending on the situation, source reduction (e.g., removal of stagnant water), biological control (e.g., introduction of natural predators such as dragonflies), trapping, using Malathion mosquito oil (MLO) to kill mosquito larvae and pupae in the aquatic stage, and / or using insecticides to kill larvae and / or adults can be used. Summary of the Invention

[0005] The object of the present invention is to provide a biologically - sourced and biodegradable solution that leads to or at least reduces the number of mosquitoes that are dangerous disease vectors from the larval stage by developing a surface - spraying oil that effectively kills mosquito larvae.

[0006] The object of the present invention is to provide a composition for killing mosquitoes at the larval stage (when they are least harmful).

[0007] The object of the present invention is to provide a composition that does not contain mineral oil, is non - toxic to the environment, and thus contains bio - sourced oil.

[0008] The object of the present invention is to provide a composition for effectively killing mosquito larvae, with a mortality rate of approximately 100% within 2 days, and a high mortality rate within 24 hours, preferably with a mortality rate greater than 85% for Aedes aegypti, preferably with a mortality rate greater than 90% for Anopheles stephensi, and preferably with a mortality rate greater than 90% for Culex quinquifasciatus.

[0009] Accordingly, the present invention relates to the use of a composition for killing mosquito larvae, the composition comprising:

[0010] - at least one oil having a kinematic viscosity at 40 °C of 1.5 mm 2 / s to 4 mm 2 / s, a flash point of 80 °C to 150 °C, a pour point of -80 °C to -50 °C, and a boiling point of 200 °C to 350 °C,

[0011] wherein, relative to the total weight of the composition, the amount of the oil is greater than 94% by weight, preferably greater than 98% by weight; preferably, relative to the total weight of the composition, the amount is 98% by weight - 99.7% by weight, and

[0012] - at least one surfactant selected from amphiphilic surfactants,

[0013] wherein, relative to the total weight of the composition, the amount of the surfactant is 0.25% by weight to 6% by weight.

[0014] The kinematic viscosity of the oil at 40 °C is measured, for example, according to ASTM D445 standard.

[0015] Preferably, the oil according to the present invention has a kinematic viscosity at 40 °C of 1.6 mm 2 / s to 4 mm 2 / s, 1.6 mm 2 / s to 3.5 mm 2 / s, preferably 2 mm 2 / s to 4 mm 2 / s, preferably 2.5 mm 2 / s to 3.5 mm 2 / s.

[0016] The flash point of the oil is measured, for example, according to ASTM 93 standard.

[0017] Preferably, the flash point of the oil is 80 °C to 130 °C, preferably 100 °C to 130 °C, more preferably 120 °C to 130 °C.

[0018] The pour point of the oil is measured, for example, according to ASTM D97 standard.

[0019] Preferably, the pour point of the oil is from -65°C to -50°C, more preferably from -60°C to -50°C.

[0020] The boiling point of the oil is measured, for example, according to ASTM D86 and D2887 standards.

[0021] Preferably, the boiling point of the oil is from 210°C to 345°C, more preferably from 230°C to 345°C, even more preferably from 250°C to 300°C. Detailed Embodiments

[0022] According to a preferred embodiment, the oil as defined above has a kinematic viscosity at 40°C of 2 mm 2 / s to 4 mm 2 / s, a flash point of 80°C to 150°C, a pour point of -80°C to -60°C, and a boiling point of 200°C to 350°C.

[0023] According to an embodiment, the oil of the composition as defined above has a kinematic viscosity at 40°C of 2 mm 2 / s to 4 mm 2 / s, a flash point of about 126°C, a pour point of -60°C, and also has a boiling point of 226°C to 316°C.

[0024] According to an embodiment, relative to the total weight of the oil, the amount of isoparaffin in the oil of the composition used according to the present invention is greater than 80% by weight.

[0025] According to an embodiment, in the oil as defined above, the amount of naphthenes is less than 20% by weight relative to the total weight of the oil.

[0026] According to an embodiment, in the oil as defined above, the amount of aromatics is less than 50 ppm by weight relative to the total weight of the oil, and even preferably less than 20 ppm by weight relative to the total weight of the oil. This amount is measured, for example, by the standard method ASTM UOP 495.

[0027] According to an embodiment, relative to the total weight of the oil, the amount of isoparaffin in the oil of the composition used according to the present invention is greater than 80% by weight; the amount of naphthenes is less than 20% by weight relative to the total weight of the oil, and wherein the amount of aromatics is less than 50 ppm, and even preferably less than 20 ppm by weight relative to the total weight of the oil. These amounts are measured, for example, according to ASTM D5443 standard.

[0028] Preferably, the oil as defined above consists mainly of isoparaffin and contains no naphthenes or aromatics.

[0029] The oil in the composition as defined above is preferably sustainable, safe and odorless. It is used as an alternative to conventional mineral oils. Thus, such oils include, for example, renewable isoparaffins derived from 100% plant - sourced raw materials. This oil preferably has a low pour point of up to - 80 °C and a high flash point of up to 150 °C, and also preferably has a boiling point in the range of 200 °C to 350 °C.

[0030] The oil according to the invention is preferably characterized by its low aromatic content and is classified as being readily biodegradable.

[0031] According to an embodiment, the oil as defined above is obtained from a biological source. Preferably, the oil as defined above is a vegetable oil, more preferably derived from palm oil.

[0032] Preferably, measured according to the OECD 306 standard, the oil has at least 60% biodegradability within 28 days.

[0033] According to an embodiment, relative to the total weight of the composition, the composition used according to the invention comprises from 0.25% to 2% by weight of a surfactant.

[0034] The surfactant as defined above is preferably a surfactant that reduces the surface tension of the oil, thereby increasing its spreading and wetting properties.

[0035] Preferably, the surfactant is selected from surfactants approved by the FDA and thus contributes to the uniform spreading of the oil on the water surface.

[0036] The surfactant is amphiphilic, which means that the corresponding molecular moieties are hydrophilic (water - soluble) and part are lipophilic (soluble in lipids or oils).

[0037] According to an embodiment, the surfactant has an HLB of from 2 to 6.

[0038] As a preferred surfactant, ABA - type copolymers can be cited.

[0039] Preferably, the surfactant of the composition according to the invention is a poly(ethylene oxide) - 10 - hydroxystearic acid block copolymer.

[0040] In particular, the composition used according to the invention includes the commercial product Hypermer 1083 (Croda) as a surfactant.

[0041] The surfactant is preferably an ABA copolymer emulsifier with a molecular weight of 2,041 g / mol and a hydrophilic - lipophilic balance (HLB) ratio in the range of 4.3 to 5.

[0042] The surfactant as defined above can preferably enhance the spreading property of oil on the water surface without affecting its ecotoxicity. The surfactant has been previously used in water treatment applications and is even FDA-approved.

[0043] Preferably, the composition does not contain any mineral oil and does not contain any petroleum fractions.

[0044] According to an embodiment, when measured according to the OECD 306 standard, the composition according to the present invention has at least 60% biodegradability within 28 days.

[0045] The compositions used according to the present invention have many advantages, in particular they do not contain toxic chemicals / pesticides, they have excellent coverage on the water surface, they spread rapidly on still water surfaces, and / or they do not leave a dark oil film.

[0046] Furthermore, the main components in the compositions used according to the present invention are not ecotoxic and are thus safe for aquatic organisms.

[0047] Preferably, the mosquito larvae are Aedes mosquito larvae, Anopheles mosquito larvae or Culex mosquito larvae, preferably Aedes aegypti mosquito larvae, Anopheles stephensi mosquito larvae or Culex quinquifasciatus mosquito larvae.

[0048] The present invention also relates to a method for killing mosquito larvae, especially a method for killing mosquito larvae in an aqueous medium, comprising applying the composition as defined above on the water surface.

[0049] According to an embodiment, the composition is sprayed or poured on the water surface.

[0050] According to an embodiment, the composition is sprayed or poured on open water bodies (such as ponds, canals or ditches) where mosquito larvae are likely to breed.

[0051] Preferably, once the composition is sprayed or poured, mosquitoes will not lay eggs on the oil-covered water surface.

[0052] The composition used according to the present invention is effective for killing mosquito larvae and, within 24 hours of application, preferably achieves a very high mortality rate for Anopheles stephensi (>90%), Aedes aegypti (>85%) mosquito larvae and Culex quinquifasciatus (>90%).

[0053] The present invention also relates to a composition as defined above, wherein the oil and the surfactant are as defined above.

[0054] Accordingly, the present invention also relates to a composition comprising:

[0055] - at least one oil having a kinematic viscosity at 40 °C of 1.5 mm 2 / s to 4 mm 2 / s, a flash point of 80 °C to 150 °C, a pour point of -80 °C to -50 °C, and a boiling point of 200 °C to 350 °C,

[0056] wherein, relative to the total weight of the composition, the amount of the oil is greater than 94% by weight, preferably greater than 98% by weight, and preferably, relative to the total weight of the composition, the amount is 98% by weight - 99.75% by weight, and

[0057] - at least one surfactant selected from amphiphilic surfactants,

[0058] wherein, relative to the total weight of the composition, the amount of the surfactant is 0.25% by weight to 6% by weight.

[0059] Examples

[0060] Preparation of the composition according to the present invention

[0061] In a clean beaker, take the weighed oil. Dropwise add the required amount of surfactant thereto. Use a magnetic stirrer to mix them in the beaker at 800 rpm for 15 minutes.

[0062] The following oils were used as the oils in the compositions according to the invention:

[0063] Parameter Unit Oil 1 Oil 2 Oil 3 Density at 15 °C <![CDATA[kg / m 3 > 780.3 783.3 764 PMCC flash point ℃ 125 128 84 Pour point ℃ -60 -54 -54 Kinematic viscosity at 40 °C cSt 2.944 3.207 1.61 Mononuclear aromatics ppm <20 <20 <20 Initial boiling point ℃ 266.6 237 211 Final boiling point ℃ 296.6 343 244 Biodegradability (OECD 306 standard) - 83% in 28 days n.d. n.d.

[0064] As the surfactant, the composition comprised various amounts of Hypermer 1083 surfactant (Croda). The following compositions C1 to C7 (comprising one oil (oil 1 or oil 2) and surfactant) were prepared:

[0065]

[0066] The following table shows the physical properties of compositions C1 to C5 as defined above.

[0067]

[0068]

[0069] The surfactant was used in a proportion of 0.5% by weight to 6% by weight. The results shown in the above table render the composition suitable for use as a diffusion oil for larvicidal action. For example, it has a kinematic viscosity @ 21.1 °C < 10 cSt and a flash point > 65 °C, which is beneficial for this application.

[0070] In addition, it has a spreading pressure higher than 4.6×10 -2 N / m, which allows it to be easily used as a spreading oil at the I level for larvicidal applications.

[0071] However, for formulations containing surfactants, the stability of the film remains unchanged, but fails for pure oils.

[0072] In these formulations, 0.5% was chosen as the optimum value because it requires less surfactant dose and has lower miscibility between the water layer and the oil layer. In addition, larvicidal toxicity tests were conducted on formulations including 0.5% and 1%.

[0073] The test results shown below demonstrate that for an application of 12 ml / m², the optimum amount of 0.5% surfactant is good enough to achieve a larvicidal toxicity of >75% for Aedes species and >90% for Anopheles species.

[0074] Larvicidal activity of the composition according to the present invention

[0075] To test the larvicidal activity of the composition according to the present invention, glass beakers with a capacity of 500 ml were used. Early fourth-instar larvae (25) of the required mosquito species were transferred from a standard colony to each 500 ml glass beaker containing 250 mL of distilled water. After removing the dead volume from 15 beakers containing 250 ml, the recommended doses (0.02 ml, 0.04 ml & 0.05 ml, corresponding to the equivalent doses of 4.8 ml / m 2 , 9.6 ml / m 2 and 12.0 ml / m 2 in the field) of the test substance were gently added to the water surface to spread the test substance film without any turbulence.

[0076] The same number of control beakers were filled with 250 ml of water containing 25 larvae. No larval feed was added.

[0077] Three sets of experiments were conducted on two mosquito larvae, with five replicates for each concentration.

[0078] The larval mortality of each test substance and control was recorded at 24, 48, and 72 hours of exposure. Moribund larvae were counted and recorded as dead larvae to calculate the mortality percentage.

[0079] Only tests with less than 10% pupation of larvae at all concentrations were considered valid. In the tests conducted, the control mortality was less than 5%, so the test was considered valid and the corrected mortality was not adjusted using the Abbott formula.

[0080] The tests were carried out according to the WHO specification "Larvicidal oil without insecticide" [WHO / SIF / 23.R1].

[0081] Compositions C1 and C3 according to the invention (containing oil 1) have been tested and the results obtained are included in the table below.

[0082]

[0083] Compositions C6 and C7 according to the invention (containing oil 2) have been tested and the results obtained are included in the table below.

[0084]

[0085] The results in the table above show that the compositions according to the invention are effective in killing mosquito larvae, especially those from Aedes aegypti and Anopheles stephensi, as well as mosquito larvae from Culex quinquefasciatus.

[0086] Comparative example

[0087] The following includes the results of a comparison with a commercially available larvicidal composition called "FLO-9" (a mineral oil-based product) produced by Fine Orgokem Private Limited, India.

[0088] FLO-9 has the following chemical composition:

[0089] Sample properties Area % n-alkanes 14.55 iso-alkanes 19.96 naphthenes 1.68 isocyclic naphthenes 10.72 dicyclic naphthenes 19.05 tricyclic naphthenes 12.78 Aromatics (mononuclear aromatics + diaromatics + triaromatics) 21.27

[0090] This mineral oil-based product has the following physicochemical properties:

[0091] Property Method Unit FLO-9 Kinematic viscosity at 40 °C ASTM D445 <![CDATA[mm 2 / s]]> 4.793 Pour point ASTM D97 ℃ -12 Pensky Martens closed cup flash point ASTM D93 ℃ 51 IBP (Initial boiling point) ASTM 2887 ℃ 152 FBP (Final boiling point) ASTM D2887 ℃ 394 Calcium content ASTM D5185 mg / kg 12 Nitrogen content ASTM D4629 mg / kg 347 Sulfur content ASTM D5453 mg / kg 1340

[0092]

[0093]

[0094] (Note: A dose of 0.02 ml corresponds to an actual application dose of 4.8 ml per square meter, 0.04 ml corresponds to an actual application dose of 9.6 ml per square meter, and 0.05 ml corresponds to an actual application dose of 12 ml per square meter).

[0095] In summary, the efficacy in killing mosquitoes against Aedes aegypti and Anopheles stephensi has been significantly improved: a 100% mortality rate within 48 hours compared to FLO-9 (44.9% for Aedes aegypti and 69.8% for Anopheles stephensi).

[0096] Therefore, the efficacy of the bio-sourced and biodegradable oil has been improved compared to the underperforming mineral oil (FLO-9).

[0097] In the formulations proposed in the present application, 0.05 ml (equivalent to 12.0 ml / m²) results in a mortality rate of 75% for *Aedes aegypti* and 90% for *Anopheles stephensi* after 24 hours, while in the case of mineral-based oils, as reported in some specifications, 0.04 ml (equivalent to 9.6 ml / m²) reaches its mortality rate after 24 hours. However, tests on such commercial products (mineral-based FLO-9) have shown negative results even within 72 hours.

Claims

1. Use of a composition for killing mosquito larvae, said composition comprising: - At least one oil having a kinematic viscosity at 40 °C of 1.5 mm 2 / s to 4 mm 2 / s, a flash point of 80 °C to 150 °C, a pour point of -80 °C to -50 °C, and a boiling point of 200 °C to 350 °C, wherein, relative to the total weight of the composition, the amount of the oil is greater than 94% by weight; and - at least one surfactant selected from amphiphilic surfactants, wherein, relative to the total weight of the composition, the amount of the surfactant is from 0.25% to 6% by weight.

2. The use according to claim 1, wherein relative to the total weight of the oil, the amount of isoparaffin in the oil is greater than 80% by weight; relative to the total weight of the oil, the amount of naphthenes is less than 20% by weight; and wherein relative to the total weight of the oil, the amount of aromatics is less than 50 ppm by weight.

3. The use according to claim 1 or 2, wherein the oil is obtained from a biological source.

4. The use according to any one of claims 1 - 3, wherein the oil is derived from palm oil.

5. The use according to any one of claims 1 - 4, wherein the composition does not contain any mineral oil and does not contain any petroleum fractions.

6. The use according to any one of claims 1 - 5, wherein measured according to the OECD 306 standard, the oil has at least 60% biodegradability within 28 days.

7. The use according to any one of claims 1 - 6, wherein relative to the total weight of the composition, the amount of the surfactant is from 0.25% to 2% by weight.

8. The use according to any one of claims 1 - 7, wherein the HLB of the surfactant is from 2 to 6.

9. The use according to any one of claims 1 - 8, wherein the surfactant is poly(ethylene oxide)-10-hydroxyoctadecanoic acid block copolymer.

10. The use according to any one of claims 1 - 9, wherein measured according to the OECD 306 standard, the composition has at least 60% biodegradability within 28 days.

11. The use according to any one of claims 1 to 10, wherein the mosquito larvae are Aedes mosquito larvae, Anopheles mosquito larvae or Culex mosquito larvae, preferably Aedes aegypti mosquito larvae, Anopheles stephensi mosquito larvae or Culex quinquefasciatus mosquito larvae.

12. A method for killing mosquito larvae, especially in an aqueous medium, comprising applying a composition on the water surface, wherein the composition comprises: - at least one oil having a kinematic viscosity at 40 °C of 1.5 mm 2 / s to 4 mm 2 / s, a flash point of 80 °C to 150 °C, a pour point of -80 °C to -50 °C, and a boiling point of 200 °C to 350 °C, wherein, relative to the total weight of the composition, the amount of the oil is greater than 94% by weight; and - at least one surfactant selected from amphiphilic surfactants, wherein, relative to the total weight of the composition, the amount of the surfactant is from 0.25% to 6% by weight.

13. The method according to claim 12, wherein the composition is sprayed or poured on the water surface.

14. A composition, comprising: - At least one oil having a kinematic viscosity at 40 °C of 1.5 mm 2 / s to 4 mm 2 / s, a flash point of 80 °C to 150 °C and a pour point of -80 °C to -50 °C, and having a boiling point of 200 °C to 350 °C, wherein, The amount of the oil is greater than 94% by weight relative to the total weight of the composition; and - at least one surfactant selected from amphiphilic surfactants, wherein the surfactant is a poly(ethylene oxide)-10-hydroxyoctadecanoic acid block copolymer, wherein the amount of the surfactant is from 0.25% to 6% by weight relative to the total weight of the composition.

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