Control of Rape Stem Weevil

The rape stem weevil, which belongs to the order Coleoptera, is also known as the rape weevil. It is one of the important pests in rapeseed production and is distributed in rapeseed production areas throughout China. Mainly in the larvae in the stem borer damage, adults can also damage the leaves and bark. In severe years, the average number of damaged stems is as high as 70%, and production is reduced by 2 to 40%. In addition to harming rapeseed, it also harms other cruciferous vegetables.
First, the morphological characteristics adults: body length 3 - 3.5 mm gray black, grayish white honey hair. The malleolus extending from the head is slender and cylindrical, not shorter than the pronotum, extending in the middle of the anterior chest. The tentacles are geniculate, and in the front part of the coronal section, the antennae are straight. The pronotum is thickly punctured, with a central concave line, and the front slightly upward. There are 9 longitudinal grooves on each eel wing. The back side of the chest is large and visible from the back, embedded between the prosthodontic plate and the elytra.
Eggs: oval, 0.6 mm long, 0.3 mm wide, slightly yellowish milky white.
Larvae: milky white at the beginning of the incubation and later turned yellowish white. Body length 6-7 mm, spindle-shaped. Big head, brown, no foot.
蛹: Nude pupa, spindle-shaped. The milky white is slightly yellow, 3.5-4 mm long and 2 mm wide. The soil surface is smooth and oval.
Second, the occurrence of the law of rapeseed stem as a generation of a year, with adults in the rapeseed soil in the winter. The adults of the stalk larvae overwinter winter, migration activities, surface temperature, temperature in the main conditions, the temperature exceeds 28 °C, the adults will be buried or in the shade of weeds, litter and leaves underground over the summer, the temperature is generally not active at 5 °C , 15-20 °C plus the most glorious activities, more than 24 °C weakened.
In winter, the adults of the overwintering winter in our province had unearthed activities. In early March, mating and spawning occurred. During spawning, females drilled a small hole on the tender stem of the rapeseed with a mouthpart and produced eggs in the hole, one egg per hole. , Each stem can produce 2 - 37 capsules, spawning period consistent with rapeseed convulsions, egg period of about 10 days. After hatching in mid-to-late March, the feeding hazards are drilled up and down the stem. The larvae often live together in the stems with 10-20 heads, eating the stems into a tunnel, the pith part being damaged, and being blown by the wind and easily broken down. The stems are often swollen or distorted until they are cracked. The growth, branching and junction angles of the affected plants are hindered, and the early yellow cannot be promoted to survive and the whole plant withers. About 20-25 days of the larval period, the instar larvae in the middle and late April and end of the year are drilled into the soil from the stalk to make pupa. The pupa period is about 20 days, and the pupa is about 3 cm above the surface of the earth. In the middle and late May, the larvae emerged before the rape harvest. For adults. Adults only eat the epidermis of leaves and stems, which are far less harmful than larvae. After rape is harvested, the adult sneak into the soil in the summer, the fall from September to October can be active for a period of time.
Third, prevention and control measures
1, soil treatment According to the determination of scouring soil, most of the adult worms in the ground 5-15 cm plow layer overwintering summer, rapeseed before sowing, select with 40% methyl isophos, 50% phoxim 250-300 ml, 40-50 kilograms of mixed soil per acre, combined with deep-grained sugar glycosides, can both effectively kill stems like adults and also treat other underground pests.
2, comprehensive prevention and control of rotation to overcome continuous cropping; transformation of cultivation measures, nurturing seedlings overwintering, and enhance plant resistance; irrigation of convulsions, change the survival conditions of the stalks of stalks as winter overwintering, eradication of weeds, eliminate litter.
3. Chemical control dusting: The control effect of rape stem larvae is best when spring adults have begun to move and have not yet laid eggs. Can choose to use 1.5% dimethoate powder, 2.5% trichlorfon powder, 2.5% 1605 powder, 4.5% Alpha powder or 2.5% phoxim powder, spray 2 kg per acre.
Spraying: Use a systemic agent of 20 milliliters of long-acting spirit per acre plus 2.5% of enemies to kill 10 milliliters of water to prevent the spraying of 40 kilograms of water.
Smearing: After the convulsion, when the initial damage appears on the stem, use 1:3 monocrotophos lanolin to slowly spread and apply the stemming agent and apply it under the victim. The effect is good.

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