JP2017031057A - Pest control agent for mosquito larvae and control method for mosquito larvae - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pest control agent for mosquito larvae that has small environmental burden and can efficiently control mosquito larvae with a small amount of agent.SOLUTION: Provided is a pest control agent for mosquito larvae characterized in containing an insecticidal protein against mosquito larvae that is produced by microorganism, in particular Bacillus thuringiensis, and an attractant for mosquito larvae. In said pest control agent, it is preferable that the attractant be an attractant also having an attracting action for predatory organisms of mosquito larvae. By applying the pest control agent to the habitat of mosquito larvae, mosquito larvae can be efficiently controlled with a small amount of active ingredients.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a mosquito larvae control agent and a mosquito larvae control method.

There are many mosquito-borne infections worldwide, especially in tropical and subtropical areas. Although mosquito-borne infections include dengue fever, malaria, and West Nile fever, symptomatic treatment is currently the main treatment, and measures to prevent mosquito bites are the most important.
Dengue fever occurs particularly in Southeast Asia, South Asia, Central and South America, and the Caribbean, and it is estimated that approximately 100 million people will develop annually worldwide. Proboscis fever was once an endemic disease in Southeast Asia, but the habitats of Aedes aegypti and Aedes albopictus that mediate with global warming have expanded, and the endemic areas have also expanded.
Aedes mosquitoes also occur in urban areas because they occur even in water collected in drains, empty cans, old tires, etc., and this is partly due to the rapid increase in population and congestion in endemic areas. is there. There is no special treatment for dengue fever, and only symptomatic treatment is given depending on the symptoms. Also, since there are no vaccines or preventive drugs, the only preventive measure is to prevent mosquito bites.

As mosquito control agents, there are mosquito control agents containing pyrethroid compounds or organophosphorus compounds as active ingredients, and these control agents are used by spraying them on the sites of adult mosquitoes. Such pesticides are also widely used in developing countries because of their relatively low production costs.
On the other hand, although the method of spraying the above-mentioned pesticide is effective in a limited space such as a room, it is impossible to completely annihilate adult mosquitoes in the outside world, and mosquito generation itself cannot be suppressed.

In order to more efficiently suppress the generation of mosquitoes, it can be said that it is an effective means to eliminate them at the stage of mosquito larvae (bowler).
As a method for controlling mosquito larvae, there is a method of spraying insecticidal components such as pyrethroid compounds and organophosphorus compounds to water sources such as water tanks, swamps, rivers, and puddles where mosquito larvae are generated. However, in order to kill mosquito larvae by such insecticidal components, it is necessary to spray at a high concentration, but organisms other than mosquito larvae may also be killed by the toxicity of the drug, from the point of environmental load There was a problem.

  On the other hand, as one of the methods for controlling mosquitoes, there is an insecticidal method for feeding mosquito larvae with an insecticidal protein having insecticidal activity only against mosquito larvae (bowfra) (for example, see Non-Patent Document 1). Such insecticidal proteins are activated by proteases in the intestine of mosquito larvae and exhibit insecticidal activity against mosquito larvae.

Glare T. R., O'Callaghan M. 1998. Environmental and health impacts of Bacillus thuringiensis israelensis. Report prepared for the New Zealand Ministry of Health.New Zealand Ministry of Health, Wellington, New Zealand.

The insecticidal method using an insecticidal protein disclosed in Non-Patent Document 1 has a small environmental load, but the insecticidal protein is expensive. For example, when used extensively such as in swamps and rivers, a concentration that exhibits a sufficient insecticidal action It is not realistic to do.
Under such circumstances, an object of the present invention is to provide a mosquito larvae control agent and a mosquito larvae control method that have low environmental impact and can efficiently control mosquito larvae with a small amount of drug. is there.

  As a result of intensive studies to solve the above problems, the present inventor has found that the following inventions meet the above object, and have reached the present invention.

That is, the present invention relates to the following inventions.
<1> A mosquito larvae control agent comprising an insecticidal protein against mosquito larvae produced by microorganisms and an attractant for mosquito larvae.
<2> The pesticide according to <1>, wherein the microorganism is Bacillus thuringiensis.
<3> The pesticide according to <1> or <2>, wherein the attracting substance is an attracting substance that also has an attracting action for predators of mosquito larvae.
<4> The pesticide according to <3>, wherein the attractant is a krill-derived attractant.
<5> The pesticide according to any one of <1> to <4>, which contains a foamable component.
<6> A method for controlling mosquito larvae, which comprises applying the insecticide according to any one of <1> to <5> to a mosquito larvae habitat.

  ADVANTAGE OF THE INVENTION According to this invention, the mosquito larvae control agent and the mosquito larvae extermination method which can control a mosquito larva with a small amount of active ingredients are provided.

It is a schematic diagram of the water tank used for screening of an attracting substance. It is a figure which shows the mobility of the mosquito larva after 60 minutes. It is a figure which shows the comparison (time course of mortality) of the insecticidal effect of the mosquito larva by the presence or absence of an attractant (krill powder).

  Hereinafter, the present invention will be described in detail with reference to examples and the like, but the present invention is not limited to the following examples and the like, and can be arbitrarily modified and implemented without departing from the gist of the present invention.

The present invention relates to a mosquito larvae control agent (hereinafter referred to as “control agent of the present invention”) containing an insecticidal protein against mosquito larvae and a mosquito larvae attractant produced by microorganisms. Although mentioned later in detail, the suitable example of the microorganisms with respect to the mosquito larva is Bacillus thuringiensis (Bacillus thuringiensis).
Hereinafter, in this specification, Bacillus thuringiensis (Bacillus thuringiensis) is referred to as “BT”, and “microbial-produced insecticidal protein against mosquito larvae” is referred to as “insecticidal protein according to the present invention” or simply In some cases, it is referred to as “insecticidal protein”, and “attracting substance of mosquito larva” is sometimes referred to as “attracting substance according to the present invention” or simply “attracting substance”.

  When the pesticide of the present invention is applied to a place where mosquito larvae live, insecticidal proteins and attractants contained in the pesticide elute. Mosquito larvae are attracted to the vicinity of the repellent by an attractant having an effect of attracting larvae, and mosquito larvae are killed by insecticidal proteins. In this way, the synergistic effect of the attractant of mosquito larvae and the insecticidal protein makes it possible to obtain more effects than when these attractant and insecticidal protein are used individually. The mosquito larvae can be controlled efficiently.

  Hereinafter, the constituent components of the pesticide of the present invention will be described in more detail.

(Insecticidal protein)
The insecticidal protein contained in the pesticide of the present invention is an insecticidal protein against mosquito larvae produced by microorganisms. The microorganism may be any microorganism that can produce an insecticidal protein against mosquito larvae, and examples thereof include Bacillus thuringiensis (BT), which is a kind of soil bacteria, and Bacillus sphaericus, and BT is preferred.

The insecticidal protein according to the present invention produces a crystalline protein adjacent to a spore when a microorganism, such as BT, forms a spore in a vegetative cell, which protein is in the gut of a particular insect, It is activated by protease and exhibits insecticidal activity against specific insects.
BT has different insecticidal activity depending on its serotype (subspecies), and as a BT that can produce insecticidal proteins against mosquitoes (including larvae), which are dipteran insects, BT is active against lepidopterous and diptera The serotypes (subspecies) shown are kurstaki and aizawai, and islaelensis that is active against dipteran insects. Of these, isralensis is preferable.
The mosquitoes (including larvae) to be controlled are not particularly limited, and include the genus Nagahashi, Musca, Aedes, Anopheles, etc., and Aedes aegypti and Aedes albopictus causing causative fever are also suitable. In addition, dipterous insects (including larvae) other than mosquitoes, such as giant flies and chironomids, can be controlled.

  A suitable example of the insecticidal protein is a commercially available effervescent tablet “MosKiller” (Kyushu Medical Co., Ltd.) containing pesticidal protein against mosquito larvae produced by BT.

(Attracting substance)
The attracting substance contained in the pesticide of the present invention may be a natural product or a synthetic product as long as it has a attracting action against mosquito larvae. On the other hand, an attracting substance derived from a natural product is preferable from the viewpoint of reducing the environmental load, and examples of a raw material for the attracting substance derived from a natural product include krill, pepper, sweet potato, and bell pepper. These attractants can be used alone or in combination of two or more at any ratio.

  As long as the attracting substance does not lose its attracting action, the raw material may be used unprocessed or may be used as a processed product such as a dried product or an extract. Specifically, the raw material is blended into the pesticide as a chopped and ground form, the dried product is pulverized and powdered, and the extract is liquid. The "extract" is a material whose active ingredient content is increased by squeezing or solvent-extracting the target raw material, or dried and shredded as necessary. It is a general concept. Specifically, an extract obtained as a raw material of the attractant, a diluted solution or a concentrated solution of the extract, or any of these roughly purified products or purified products are included. In addition, the dried material obtained by drying an extract liquid shall also correspond to an extract.

In addition, the attracting substance according to the present invention is preferably an attracting substance having an attracting action for predators of mosquito larvae. Examples of such predatory organisms include small fishes, amphibians such as frogs, insects such as dragonfly larvae, and the like.
Such an attractant not only attracts mosquito larvae, but also attracts predators of mosquito larvae. In addition to the insecticidal action of the above insecticidal proteins, Because it is predated, it has the advantage that mosquito larvae are synergistically controlled.
Among the attracting substances having both the attracting action of mosquito larvae and the attracting action of predators, a attracting substance derived from krill can be cited as a suitable example.
Krill is also a very safe raw material that is also used for food and fishing bait, and since it is inexpensive, it can suppress the increase in the price of the product.
The attractant derived from krill is highly effective in attracting small fish and has little adverse effect on organisms other than mosquito larvae.

  The ratio of the insecticidal protein to the attracting substance is insecticidal protein: attracting substance, and is usually 1: 0.01 to 10 (mass ratio), preferably 1: 0.1 to 5 (mass ratio).

(Form of pesticide)
An effective amount of the pesticide of the present invention can be blended with a carrier to form a solid preparation or a liquid preparation. The dosage form may be any form as long as it can be applied to the mosquito larvae. Specific examples of solid preparations include powders, granules, tablets, capsules, and liquid preparations include suspensions and emulsions.

A solid preparation capable of sustained release of the active ingredients (insecticidal protein and attractant) is preferable in that the disinfecting action by the disinfectant of the present invention can be sustained.
In the solid preparation, in addition to the insecticidal protein and the attractant, adjuvants such as excipients, binders, disintegrants, lubricants, flavoring agents and stabilizers may be used. The ratio of the insecticidal protein, the attractant and the adjuvant is appropriately selected according to the purpose.

  In particular, the pesticide of the present invention preferably contains an effervescent component in that the release of the active ingredient from the solid preparation can be enhanced. As the foaming component, a conventionally known foaming component can be used, and examples thereof include a foaming component comprising an organic acid such as citric acid, fumaric acid, tartaric acid, adipic acid and succinic acid, and a carbonate. Examples of the carbonate include sodium carbonate and sodium hydrogen carbonate.

  These preparations may contain arbitrary components used for pest control agents, control agents, and repellents as long as the object of the present invention is not impaired.

  Although depending on the form of the preparation, the total amount of the insecticidal protein and the attractant relative to the total weight of the preparation is usually 0.01 to 50% by weight, preferably 0.1 to 10% by weight, more preferably 1 to 10% by weight. Contains 5% by weight.

  The preparation can be produced by a conventionally known method. For example, (1) a method in which the insecticidal protein and the attractant are mixed with a solid carrier, a liquid carrier, and the like, and if necessary, other formulation adjuvants are added and processed; (2) the insecticidal protein , A method of forming after mixing the attracting substance and the substrate, and the like.

(Disinfection method)
The method for controlling mosquito larvae of the present invention is characterized by applying the above-described insecticide of the present invention to a place where mosquito larvae live.
Mosquito larvae habitats include water sources such as water tanks, swamps, rivers, and puddles. As described above, the pesticide of the present invention can gradually release active ingredients (insecticidal protein and attractant) and can maintain the effect over a long period of time, so even in water sources with a slow flow of water such as swamps and rivers. Effectively suppress the generation of mosquitoes.

  There are no particular limitations on the mosquitoes to be controlled, and examples include the genus Nagahashi, Musca genus, Aedes genus, and Anopheles genus. In addition, dipterous insects (including larvae) other than mosquitoes, such as giant flies and chironomids, can be controlled.

  The application amount, application frequency, and the like of the pesticide of the present invention are appropriately selected according to the target water source. For example, when using MosKiller manufactured by Kyushu Medical Co., Ltd., which is an example of a suitable commercial product, in a clean water source, about 1 m in depth and a surface area of 1 tablet per square meter are administered as a guide. For water sources with a lot of dirt, water sources with a large number of larvae, or water sources with advanced stages of larvae, the amount used is increased as necessary. The frequency of application is adjusted according to the number of remaining larvae.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

(Evaluation 1: attractant screening)
As candidates for attractants, squid meal, krill flour, skim milk, corn flour, wheat flour, red pepper powder, red pepper, shishito, green pepper and bay leaf were used.
The squid meal, krill meal, skim milk, corn meal, wheat flour, and pepper powder were suspended in water to a concentration of 20% (w / w), centrifuged to remove impurities, and a supernatant was obtained. The obtained supernatant was immersed in 100 μL of a paper disc and used for the test. About red pepper, shishito, green pepper, and bay leaf, it was cut out to about 3 mm and used as a shredded sample.
For the evaluation, a water tank having four sections was used. FIG. 1 shows a schematic diagram of a water tank used for screening attractants.
Put water (300 mL) into the aquarium with the four compartments shown in the schematic diagram in FIG. 1, put 7-11 Aedes aegypti larvae into the first compartment of the aquarium, and immerse the sample in the fourth compartment A paper disk or shredded sample 3 mm × 3 mm was placed. To prevent the effects of light, the water tank was covered with an aluminum can to prevent light from entering. To which compartment the larvae moved after 60 minutes was expressed numerically. 0% when all of the larvae entered were in the 1st section, 100% when all the larvae had moved to the 4th section, less than 60% “almost no attracting effect”, and more than 60% “with an attracting effect” And 70% or more is “particularly attractive”. FIG. 2 shows the screening results for attractants.

(Evaluation 2: Determination of the attractive concentration of krill powder)
From the result of evaluation 1, krill powder was selected as an attractant that is particularly excellent in the attracting action of mosquito larvae.
After putting 2 L of water in a circular aquarium, 50 Aedes aegypti larvae were added. 0.8 mg of krill powder was placed in a non-woven fabric and installed so as to be immersed in the water surface of a water tank.
As a control, a non-woven fabric containing nothing was placed at a position symmetrical to the non-woven fabric containing krill powder. To prevent the effects of light, the tank was covered with a black curtain to prevent light from entering. After 60 minutes, the number of larvae on the krill powder side was counted from half of the water tank. The test was repeated while exchanging water and larvae each time.
The ratio close to the krill powder side was 72.1% ± 7.0%, which was significantly higher than the control (one-sided test with a significance level of 1%). Therefore, it was found that 0.8 mg of krill powder with respect to 2 L of water, that is, 40 mg of krill powder with respect to 100 L of water, has an attracting effect on mosquito larvae.

(Evaluation 3: Comparison of insecticidal effect of larvae with and without attracting substance)
An effervescent tablet “MosKiller” (Kyushu Medical Co., Ltd.) (hereinafter referred to as “sample tablet”) containing an insecticidal protein derived from Bacillus thuringiensis strain D142 was used.

As a pesticide in the examples, sample tablets were powdered and 1% of krill powder was mixed. Fifty Aedes aegypti larvae were placed in a water tank (500 mL), and a powdered sample tablet mixed with krill powder was placed as far as possible on the water surface. As a control (comparative example), a powdered sample tablet not containing krill powder was placed in another water tank. The number of dead larvae was counted over time. The results are shown in FIG.
It turned out that the insecticide of the Example which added krill powder has a higher insecticidal effect. The LT50 (50% lethal time) had a prototype of 177 minutes, while the krill powder mixed prototype had 119 minutes. From this result, it was found that the insecticide of the example to which krill powder was added had a higher insecticidal effect.

  According to the disinfectant of the present invention, mosquito larvae can be disinfected with a small amount of active ingredients, so that mosquitoes can be generated efficiently.

Claims (6)

  An insecticide for mosquito larvae, comprising an insecticidal protein for mosquito larvae produced by microorganisms and an attractant for mosquito larvae.   The pesticide according to claim 1, wherein the microorganism is Bacillus thuringiensis.   The pesticide according to claim 1 or 2, wherein the attracting substance is an attracting substance having an attracting action for predators of mosquito larvae.   The pesticide according to claim 3, wherein the attractant is a krill-derived attractant.   The pesticide according to any one of claims 1 to 4, comprising a foamable component.   A method for controlling mosquito larvae, which comprises applying the disinfectant according to any one of claims 1 to 5 to a mosquito larvae habitat.