JPS5828846B2 - Resistant leafhopper control agent - Google Patents

Description

Detailed Description of the Invention The present invention relates to 〇-ethyl〇-O-di(2,4-dichlorophenyl)phosphate-1-
(hereinafter referred to as "phosdaifen") and 3-methylphenyl N-methyl carbamate (hereinafter referred to as "MTMC")
The present invention relates to a leafhopper control agent that is resistant to carbamate insecticides and is characterized by containing a mixture of the same and as an active ingredient.

The leafhopper is an important pest in rice cultivation that not only parasitizes rice plants and directly absorbs them, but also transmits viral diseases such as rice wilt.

Various N-methyl carbamate insecticides are frequently used because they exhibit outstanding control effects against these pests.

However, in recent years, N
- Due to the continuous use of methyl carbamate insecticides, leafhoppers that are resistant to solid agents have appeared, making it difficult to control them.

The present inventors have conducted extensive research in view of the current situation.

As a result, it was discovered that a mixture of phosdaifen and MTMC showed a higher control effect on resistant leafhopper than expected with each agent alone.

Phosdaifen, a component of the mixture of the present invention, is
It is a known agricultural and horticultural fungicide as disclosed in Japanese Patent No. 20514, and it shows an excellent control effect particularly against blast disease, but it has almost no insecticidal activity at normal concentrations.

On the other hand, MTMC is a known paddy rice insecticide, as described in pages 72 and 73 of the "Pesticide Handbook 1976 Edition" (published by the Japan Plant Protection Association), and is highly effective against susceptible leafhoppers, but is highly effective against resistant leafhoppers. A sufficient control effect cannot be obtained.

By mixing these two types of chemicals, the pesticidal agent according to the present invention exhibits a high effect against resistant leafhoppers, and at the same time becomes an effective agent against the same insect pests, it is also effective against pests such as brown-bottomed planthoppers, brown planthoppers, stink bugs, and rice blast disease. It has the advantage of being effective against a wide range of applications.

Similar to widely used agricultural chemicals, the pesticidal agent according to the present invention is prepared by adding various auxiliary agents such as surfactants, dispersants, and wetting agents to a solid or liquid carrier to form powders or wettable powders. It can be used in formulations such as emulsions, granules, etc.

Next, some examples of the present invention will be shown, but the types of adjuvants, amounts added, and mixing ratios of active ingredients are not limited to the examples.

Note that all figures in the middle part of the examples indicate parts by weight.

Example 1 (Emulsion) 25 parts of phosdaifen, 25 parts of MTMC, 35 parts of xylene
1 part and 15 parts of Tsurupol (emulsifier manufactured by Toho Chemical Industry Co., Ltd.) are mixed to prepare an emulsion.

Example 2 (Powder) 2 parts of phosdaifen, 2 parts of MTMC, 1 part of white carbon, 20 parts of talc and 75 parts of clay are uniformly mixed and ground to obtain a powder.

Test Example 1 Resistant black leafhopper control effect test A diluted solution of a predetermined concentration of the emulsion prepared according to Example 1 was applied to potted rice plants at the 4th to 5th leaf stage at a rate of 1001 per 10 ares on a turnchill using a spray gun. did.

After air-drying, cut the rice stem leaves and place them in a test tube with a diameter of 2C1'fL and a length of 20cTL.
24 hours after 0 insects were lost, the number of supine insects was counted.

The test was conducted in three zones at one concentration, and the average supine insect rate was determined.

The leafhoppers used in the experiment were collected from Amakusa, Kumamoto Prefecture, and reared for generations, and they exhibit high resistance to Carbame-1 insecticides.

The results are shown in Table 1.

Note that the expected values in the table were determined using the Bliss formula.

Based on the data in Table 1, Carpenter
LC5o(5
The expected value (0% lethal drug concentration) was determined, and the synergistic effect of the insecticidal effect by mixing the active ingredients was calculated from the comparison with the actual value.

In this case, synergistic dust 1 shows an additive effect, if it is smaller than ■, it shows an antagonistic effect, and if it is larger than 1, it shows a synergistic effect.

When the number of synergistic particles is 2 or more, it indicates that the synergistic effect is significant.

The results are shown in Table 2.

Test Example 2 Changes in the sensitivity of the black leafhopper population due to continuous selection of drugs (from Okayama Prefecture) The black leafhoppers used in the test were collected from a rice field in Kojima District, Okayama Prefecture, and then exposed to light for 16 hours at a constant temperature of 25°C for 8 hours. The rice was bred for generations under dark conditions using sprouted rice, which was subsequently subjected to selection and breeding, and drug assays were conducted at any time.

Test 1 As a test method, first, a drug concentration diluted solution 10- with a selection rate of around 50% of the test drug prepared according to Example 1,
Size: 23crrLX 30crrLX 2cyrt
The seeds were sown in plastic boxes and sprouted rice plants were sprayed.

This sprouted rice is placed in a cage for breeding black leafhoppers, and approximately 1,000 adult black leafhopper cows, which have been raised for generations, are released.
After 24 hours, the surviving insects were collected with a fluke tube and released into newly prepared rice plants treated with chemicals to obtain the next generation population.

Selection was repeated in the same manner, once per generation.

In the drug test, the number of live and dead insects was investigated after 24 hours by topical application to adult female leafhoppers 3 to 4 days after emergence, and the LD5o value (μm/1) was determined.

The results are shown in Table 3.

(Note 1) LD of MTMC against black leafhopper from Okayama Prefecture before culling.

The value was 50.3 μg/g. (Note 2) LD without selection.

The value column shows the parent adults of leafhoppers that have been reared for generations without chemical selection, and the LD after 10 and 20 generations.

Claims (1)

[Claims] Shows resistance to carbamate insecticides characterized by containing a mixture of 10-ethyl 0-0-di(2,4-dichlorophenyl) phosphate and 3-methylphenyl N-methylcarbamate as an active ingredient. Black leafhopper control agent.