Forecast of Occurrence Trend of Rice Stem Borer

First, the occurrence degree: it is estimated that the occurrence of the first generation of rice stem borer in our city is moderate and heavy, and the occurrence area of the whole city can reach more than 250000 mu, of which the early planting free field is more than 50, 000 mu.

Second, the occurrence period: the moth is seen under the lamp on April 11, the peak period of the moth is 5pm, the peak of the moth, the peak of the egg hatching period, the peak period of the first and second instar larvae, the peak period of the first and second instar larvae, the peak period of the first and second instar larvae, the peak period of the first and second instar larvae, the peak period of the first and second instar larvae, the occurrence period is 3 days later than the average of the last three years.

III. Forecast basis

1. Progress of development: this year, there were 107 live worms stripped by 4pm, with a pupation rate of 27.1%. The Eclosion rate was 2.8%. 2 pupae of grade 6, 3 of grade 5, 2 of grade 4, 5 of grade 3, 5 of grade 2, 6 of grade 1, 11 of 7th instar larvae, 18 of 6th instar larvae, 26 of 5th instar larvae, 20 of 4th instar larvae and 6 of 3rd instar larvae.

2. The amount of overwintering residual insects: there were two overwintering base surveys on April 26th last year and two growth period surveys on April 18th and April 28th of this year. There were great differences among the fields, with an average of 7930 heads per mu and 4500-780 heads per mu in the empty stubble field of Chilo suppressalis. The number of residual insects decreased by 43% 52% compared with the usual year. The mortality rate was 16 percent, 21 percent, 5.9 percentage points higher than the average of the previous three years.

3. Weather and seedling condition: the temperature and rainfall in May were normal, which had no obvious effect on the pupation and Eclosion of the overwintering generation. Our city is a single cropping rice area, while the field area of seedling field and early planting of middle rice is relatively small. The first generation of Chilo suppressalis is mainly concentrated in the seedling field and some early planting fields.

IV. Opinions on prevention and control

Although there was a great occurrence of rice leaf roller last year, and the amount of residual insects of Chilo suppressalis was controlled to a certain extent, and the continuous low temperature, rain and snow freezing weather since January this year had a certain impact on the population base and mortality of the overwintering generation of stem borer, however, according to the investigation, the area of empty stubble field this year is large, resulting in more effective source fields and high population number. All localities should attach great importance to the prevention and control of the first generation of Chilo suppressalis, overcome the idea of paralysis, harness the base of the first generation, carry out the marriage of seedlings with medicine, and reduce the difficulty of field control.

1. The time of control: during the peak period of egg hatching of the first generation of stem borer, all seedling fields and early planting fields were comprehensively controlled once, and 50 withered sheath clumps per mu were used in time in some fields with missed control and poor control effect from June 10 to 13.

2. Control agents: ① 20% Kangkuan suspension 10 ml / mu, ② 4.75% hard 30ml / mu, ③ 1.8% blue sharp EC 75ml / mu.