JPH0116801B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention provides a method for killing mosquito larvae, and more specifically, a method for selectively controlling mosquito larvae by feeding mosquito larvae with an insecticidal ingredient, which has a substantially negative effect on other aquatic organisms such as fish. The present invention relates to a novel and useful insecticidal method that does not cause harmful effects. A large number of insecticides for controlling mosquito larvae have been developed and put into practical use, but these have poor selectivity and are toxic and harmful, especially human hoarding, adverse effects on fish, destruction of natural ecosystems, etc. , causing alarming situations and developing into a major social problem. In particular, the use of dichlordiphenyltrichloroethane (DDT) and benzenehexachloride (BHC), which have been commonly used in the past, is currently completely prohibited due to their toxicity, and pyrethroid insecticides, which are currently considered the least toxic. Even though it is a chemical, its toxicity to fish cannot be ignored. In view of the above-mentioned current situation, the present inventors provide an insecticidal method that is non-polluting and low-toxic, can specifically and selectively exterminate mosquito larvae, and causes less environmental pollution of the water where the mosquito larvae live and the surrounding soil. Various studies were conducted with the aim of achieving this goal. In the process, with conventional insecticides that use contact action with pests, it is necessary to use a relatively large amount (high concentration) of insecticidal ingredients, and especially when controlling mosquito larvae living in water, it is necessary to use a uniformly constant concentration of insecticidal ingredients in the water. In contrast, large amounts of insecticidal ingredients must be sprayed to achieve this, and environmental pollution due to excessive insecticidal ingredients is unavoidable.However, it is possible to selectively feed insecticidal ingredients to insect pests without using the above-mentioned contact effect. It was thought that if possible, the desired pesticidal effect could be achieved by using an extremely small amount, and the risk of environmental pollution could be reliably avoided. As a result of further intensive research based on the above new idea, we found that when a predetermined amount of insecticidal ingredients are adsorbed onto an adsorbent whose particle size is approximately the same as that of floating organic matter, etc., which mosquito larvae feed on, this adsorbent is It has been found that the adsorbed insecticidal component hardly elutes and does not cause environmental pollution, while it exhibits toxicity (insecticidal properties) in the body when eaten by mosquito larvae, meeting the above objectives, and hereby the present invention I was able to complete it. That is, in the present invention, an insecticidal component-containing adsorptive material whose particle size is adjusted to 40 μm or less and which adsorbs and retains an insecticidal component of 1 to 45% by weight based on the weight of the adsorptive material is dispersed in water where mosquito larvae live. The present invention relates to a method for killing mosquito larvae, which comprises controlling the mosquito larvae by feeding the mosquito larvae. According to the method of the present invention, mosquito larvae can be specifically and selectively controlled without substantially causing problems of human hoarding, adverse effects on fish, or environmental pollution. Furthermore, the method of the present invention is easy to implement and has no odor or irritation. Furthermore, the insecticidal ingredient-containing adsorptive substance used in the method of the present invention can be easily prepared and does not release the insecticidal ingredient even in water, so even if an insecticidal ingredient that is unstable in water is used, an excellent insecticidal effect can be exhibited. Ru. In particular, according to the method of the present invention, the adsorbed and retained insecticidal components hardly elute in water, so that environmental pollution is not caused.
Even when used in large quantities, it causes almost no environmental pollution. In addition, the insecticidal effect is exerted within the body of the mosquito by feeding on the mosquito larvae, so a sufficient insecticidal effect can be achieved by using only a very small amount of the insecticidal component-containing adsorbent material. In the present invention, as the insecticidal component, a wide variety of known agents that exhibit insecticidal properties against mosquito larvae can be used. Representative examples include pyrethrin, cinerin, permethrin, allethrin, phthalthrin,
Pyrethroid insecticides such as resmethrin, flamethrin, and phenothrin, organophosphorus insecticides such as acephate, dichlorvos, diazinon, parathion, fenitrothion, fuentate, malathion, and disulfoton, and carbamate insecticides such as carbaryl (NAC) and propoxar (PHC). , organochlorine insecticides such as DDT and BHC, chitin synthesis inhibitors such as Deimirin, juvenile hormone-like active substances such as methoprene, anti-juvenile hormone-like active substances such as precosene, and metamorphosis hormone-like active substances such as ecdysone. Examples include insect growth disruptors such as substances. In particular, in the present invention, even if the insecticidal component itself is quite toxic, it can be used to reduce its toxicity, and even if it is difficult to apply in water due to poor stability in water, it can be used for its intended purpose. The insecticidal effect can be sufficiently exerted without substantially reducing the insecticidal effect. In addition, in the present invention, there are no particular restrictions on the adsorbent material that adsorbs and retains the insecticidal component, as long as it can adsorb the insecticidal component, but it usually has a strong adsorption ability, is porous inside, has a small bulk density, and has a small specific surface area. Large adsorbents such as chips such as activated carbon, microcrystalline cellulose, vermiculite, kaolin, sepiolite, diatomaceous earth, silica, wood flour, and more preferably activated carbon can be used. In particular, activated carbon has the ability to prevent the insecticidal ingredient-containing adsorptive substance from being washed away even when the insecticidal ingredient-containing adsorbent substance manufactured using activated carbon is applied to flowing water, resulting in a highly sustainable insecticidal effect. It has the advantage of being able to play a role. It is particularly important that the particle size of the adsorbent substance is adjusted to a size that can be ingested by mosquito larvae.
The size varies slightly depending on the type of mosquito to which the insecticidal ingredient-containing adsorptive material is applied, but it is usually 40 μm or less,
Preferably, the range is about 1 to 30 μm.
The above particle size adjustment can be carried out at any time before or after the insecticidal component is adsorbed onto the adsorbent material, using conventional crushing and classification means. The insecticidal component can be adsorbed onto the adsorbent material by a conventional method. For example, the insecticidal component is mixed with an adsorbent substance either as is or after diluting with an appropriate diluent,
Thereafter, if necessary, the diluent may be removed by air drying or vacuum fluidized bed drying. As a result of the above, the insecticidal component is positively adsorbed onto the adsorptive substance.
It is important that the amount of insecticidal component adsorbed is such that no free insecticidal component is present. Although it varies depending on the insecticidal efficacy etc., it is usually 1 to 45 per weight of adsorbent material.
Weight %, preferably about 5 to 25 weight %, is suitable. As a diluent for the above adsorption, ordinary low boiling point organic solvents such as pentane, petroleum ether,
Hexane, benzene, ether, ethyl acetate, acetone, ethanol, methanol, acetonitrile, methylene chloride, etc. can be used. In addition, for the above adsorption, various additives that can be added to ordinary insecticides, such as synergists, dispersants, suspending agents, etc., may be added to the insecticidal component diluted solution as necessary. can do. Furthermore, the above additives, etc.
After producing the insecticidal component-containing adsorptive material as described above, it may be separately added and mixed therewith. After adsorption and drying (removal of diluent), the insecticidal component-containing adsorptive material produced as described above is washed with the diluent used as necessary to ensure that it is not completely adsorbed to the adsorptive material and remains free. It is also possible to remove insecticidal components that may adhere in the form of insecticides. In addition, during the drying process, the particle size of the adsorbent material is reduced by granulation, etc.
If there is a possibility that the diameter exceeds 40μm,
Subsequently, particle size can be adjusted by crushing and classifying means. In this way, in the method of the present invention, an adsorptive material containing an insecticidal component that is fed to mosquito larvae is obtained. The substance has a form suitable for feeding on mosquito larvae and exhibits high insecticidal activity against the larvae. In addition, since the insecticidal ingredients are completely adsorbed by adsorbent substances, the amount of insecticidal ingredients leached into water or the natural environment due to their use is extremely small, and therefore has almost no negative effects such as environmental pollution or toxicity to fish etc. Completely avoidable. The insecticidal component-containing adsorptive substance can avoid the risk of environmental pollution by dispersing an extremely small amount of 12.5 μg per water into the water where mosquito larvae live, and can achieve a sufficient insecticidal control effect, making it economical. Also highly preferred. Furthermore, even when the applied amount is about 5 g, since the insecticidal component itself is completely adsorbed by the adsorbent material, its elution into water is extremely small and there is almost no risk of environmental pollution, which is advantageous. Can be used. Usually, it is preferable to disperse about 0.1 mg to 1 g in water, but the amount used can of course be increased or decreased depending on the type of water to be applied (water quality, presence or absence of water flow, etc.) and the degree of mosquito larva occurrence. can do. Further, the insecticidal component-containing adsorptive material can be sufficiently dispersed in water simply by adding the insecticide to the water. In this case, the insecticidal component-containing adsorptive material is mixed with a suitable diluent, such as the adsorbent material having a particle size that cannot be ingested by mosquito larvae, or a water-soluble material that does not adversely affect mosquito larvae's ingestion of the insecticidal component-containing adsorptive material. It can also be used in a diluted state by mixing with other agents, or it may be mixed with ordinary dispersants, suspending agents, etc. to improve dispersion in water. Thus, according to the method of the present invention, mosquito larvae living in water such as gutters, sewage, basins, lotus ponds, ponds, paddy fields, water tanks, water puddles, etc. can be sufficiently controlled, and environmental pollution etc. can be almost certainly avoided. The present invention will be explained in more detail below with reference to production examples and test examples of insecticidal component-containing adsorptive substances. Production Example 1 Activated carbon (manufactured by Takeda Pharmaceutical Co., Ltd.) is pulverized using a jet mill (manufactured by Fuji Sangyo Co., Ltd.), and the particle size is adjusted to 1 to 20 μm using a Mycolloider (manufactured by Tokushu Kika Kogyo Co., Ltd.). 85.6 g of activated carbon whose particle size has been adjusted as described above is added to a solution of 10.4 g of methoprene (96% purity) dissolved in 600 ml of petroleum ether, and the mixture is stirred for 2 hours. The resulting slurry is spread on a stainless steel vat and dried in a hot air dryer (circulation temperature approximately 40°C) to remove the solvent. Next, a solution of 4.0 g of polyoxyethylene (10) nonyl phenyl ether dissolved in 200 ml of acetone is added, and after thorough mixing, the solvent is removed using a hot air dryer (circulation temperature: about 40° C.) in the same manner as above. After removing the residual solvent in a vacuum dryer (40° C., 200 mmHg), the mixture is pulverized using the above-mentioned diet mill and the particle size is adjusted using a Mycolloider to obtain an insecticide having a particle size of 1 to 20 μm and containing 11.7% by weight of methoprene. This is designated as insecticidal component-containing adsorptive material No. 1. The above production example 1 was prepared by changing the insecticidal ingredients and their usage amounts.
In the same manner as above, the following insecticidal ingredient-containing adsorptive substance No. 2 ~
9 (particle size of 1 to 20 μm in each case).

[Table] Production Example 2 918 g of activated carbon whose particle size was adjusted to 1 to 30 μm in the same manner as in Production Example 1 was added to permethrin (purity 95%).
52 g and 30 g of dipolyoxy(8) dodecyl ether phosphate were dissolved in 600 ml of acetone, stirred for 3 hours, and then the resulting slurry was mixed using a rotary evaporator (bath temperature of about 30°C, degree of vacuum of about 200 mmHg). Dry (remove solvent). The obtained powder was further crushed and classified in the same manner as in Production Example 1 to have a particle size of 1 to 30 μm, and 5% by weight of permethrin.
Obtain an insecticide containing. This is designated as insecticidal component-containing adsorptive material No. 10. Production Example 3 Crystalline cellulose (manufactured by Asahi Kasei Corporation) was ground in a jet mill and adjusted to a particle size of 1 to 30 μm using a mycolloider. 5.2g of permethrin (95% purity) in methanol
Add 91.8 g of the crystalline cellulose whose particle size has been adjusted above to the 200 ml solution and mix well. After the mixture has been left to stand for 4 hours, the solvent is removed in a fluidized bed granulation dryer (intake temperature approximately 60° C.). Then, add 3.0 g of sodium dioctyl sulfosuccinate to methanol.
Dissolve in 100ml and spray under flowing conditions, being careful not to cause granulation. After removing the remaining solvent using a fluidized bed granulation dryer (intake air temperature: about 60° C.), the product is pulverized and classified to obtain insecticidal component-containing adsorbent material No. 11 having a particle size of 1 to 30 μm and containing 5% by weight of permethrin. The following insecticidal component-containing adsorptive materials Nos. 12 to 16 having a particle size of 1 to 30 μm are obtained in the same manner as above, while changing the insecticidal component and the amount used.

[Table] Production Example 4 85.4 g of kaolin, which was ground to 30 μm or less in the same manner as in Production Example 1, was added to a solution of 10.5 g of dichlorvos (95% purity) dissolved in 500 ml of petroleum ether.
Stir for 2 hours. Spread this slurry on a stainless steel vat and dry in a hot air dryer (circulation temperature approximately 40℃).
After removing the solvent, the mixture is crushed and classified in the same manner as in Production Example 1 to obtain an insecticidal component-containing adsorptive material having a particle size of 30 μm or less and containing 11.8% by weight of dichlorvos. Add 5.0 g of ground sodium cetyl sulfate to this and mix well. This is designated as insecticidal component-containing adsorptive material No. 17. The following insecticidal component-containing adsorptive materials Nos. 18 to 20 having a particle size of 30 μm or less are obtained in the same manner as above by changing the insecticidal component and its usage amount.

[Table] Production Example 5 A bar with a particle size of 10 to 30 μm was crushed and classified in the same manner as Production Example 1 in a solution in which 5.1 g of diazinon (98% purity) and 2.5 g of polyoxyethylene (15) cetyl ether were dissolved in 250 ml of acetone. mikuyu light
Add 92.4g and mix well. After this mixture was left to stand for 4 hours, the solvent was removed in a fluidized bed dryer (intake temperature 50°C), and then the mixture was crushed and classified again in the same manner as in Production Example 1 to obtain a particle size of 10 to 30 μm containing 5.4% by weight of diazinon. Obtain insecticidal component-containing adsorptive material No. 21. The following insecticidal component-containing adsorptive materials Nos. 22 to 25 were obtained in the same manner as above except for changing the insecticidal component and the amount used.

[Table] Production example 6 8.9g of methoprene (96% purity) was added to petroleum ether.
Add 85.0 g of activated carbon with a particle size of 1 to 20 μm as prepared in Production Example 1 to 600 ml of the solution, mix well, spread the mixture on a stainless steel vat, and dry it in a hot air dryer (circulation temperature about 40°C). , an insecticidal component-containing adsorptive material No. 26 having a particle size of 1 to 20 μm and containing 10% by weight of methoprene is obtained. Test Example 1 An absorbent substance containing an insecticidal ingredient was placed in a beaker containing 60-80 4th instar A. mosquito larvae (Gose type).
Cover with Japanese paper and place in a constant temperature room at 25℃. Check whether the mosquito larvae are alive or dead 24 hours after applying the insecticide, and calculate the mortality rate (%). The results were as shown in Table 1 below.

[Table] In addition, the insecticide concentration* in the table is the calculated value of the amount of insecticidal ingredients in the insecticidal ingredient-containing adsorptive substance used for the water in the beaker, and it is also the No. 1 insecticidal ingredient-containing adsorptive substance
The mortality rate in is expressed as the inhibition rate of emergence. The same test as above was carried out on insecticidal ingredient-containing adsorptive material No. 2.
-4, 6-8, 10, and 12-26 showed that almost the same mortality rates were obtained using the same concentrations. Test Example 2 The same test as in Test Example 1 above was conducted on insecticidal ingredient-containing adsorptive material No. 5, and its LC ₅₀ value (mosquito larva
Find the concentration of insecticide that can kill 50% of the insects. For comparison, the same test was carried out using the above insecticidal ingredients alone, that is, without adsorption to activated carbon, and the same results were obtained.
Find the _LC50 value. The results are shown in Table 2 below. The insecticide concentration has the same meaning as in Test Example 1.

[Table] Test example 3 Kadayashi female fry (average weight 102.1 mg, average height
0.8cm) Add an amount of adsorbent material containing insecticidal ingredients to the water containing 10 to 20 insects to give an insecticidal concentration of 0.1 to 50 ppm.
Inject No. 10 and calculate the mortality rate (%) of the fish 48 hours after injection. For comparison, the same test was carried out using the insecticidal component used in the production of the above insecticidal component-containing adsorptive material No. 2 (without adsorbing it to an adsorptive material).
Put it in and do it. The results are shown in Table 3 below.

[Table] From Table 3 above, the adsorptive substances containing insecticidal ingredients have extremely low toxicity and show no toxicity to fish at concentrations below 50 ppm, whereas when insecticidal ingredients are used alone, the toxicity is only 0.1 ppm. It shows a 91% fish mortality rate even at high concentrations, and it can be seen that 100% of the fish die at concentrations above 1 ppm. The same test as above was carried out using insecticidal ingredient-containing adsorptive material No.
The results of testing at concentrations of 0.1 to 10 ppm for 1 to 9 and 11 to 26 were similar to those in Table 3 above.
It was confirmed that there was no toxicity to fish at the insecticidal component concentration of 10 ppm or less.

Claims (1)

[Claims] 1. An insecticidal component-containing adsorptive material adjusted to a particle size of 40 μm or less and adsorbing and retaining 1 to 45% by weight of an insecticidal component per weight of the adsorptive material is dispersed in water where mosquito larvae live and fed to the mosquito larvae. A method for killing mosquito larvae, which method comprises controlling the mosquito larvae by using