Prevention and Control Technology of Plutella xylostella

Due to the anomalous climate in recent years and rising global temperatures, warm winter weather has been common throughout China last year, which will lead to an increase in vegetable pests this year compared with previous years. Among them, the harmful effects of Plutella xylostella on vegetables, especially cruciferous vegetables, may be particularly serious.

First, occurrence and harm

Plutella xylostella, also known as Plutella xylostella, moth, small green caterpillar, two tips, hanging insects, flying worms, etc., occur mainly in the southern provinces. Plutella xylostella mainly harms crucifer crops, among which cabbage, broccoli, cabbage, radish and rape are the most affected and can also harm tomatoes, ginger, potatoes and onions. The larvae harm the leaves, and they are most severe at the seedling stage. They often harm the central leaves. After the cabbage core, they are more harmful to the outer leaves of the plants, and can also be drilled into the core to make the leaves appear round.

Second, the morphological characteristics

Adult moths are gray-brown moths, 6 to 7 mm in length and 12 to 15 mm in wings. Before and after the wings are slender, with a longer ciliary. The first half of the forewing is light brown, and the latter half has a three-folded yellow-white ripple from the fin base to the outer edge. At rest, the two wings are stacked in a ridge-like shape, and the yellow-white portions merge into a series of triangular oblique blocks.

Third, living habits

It usually takes 3 to 6 generations every year. The north is wintering with storks. Feathering from April to May. Adults grow into night out. Adult oviposition period of up to 10 days, each female adult eggs spawning 100 to 200 capsules, eggs scattered or a few grains together, distributed in the back veins depression. The egg period is 3 to 11 days. The larvae were 4 years old and the growth period was 12-27 days. The mature larvae pupae around the veins, and the pupa period is about 9 days. The developmental temperature of Plutella xylostella is 20～23°C. The peak period in the north is from May to June and August. The most serious hazard is from May to June, and the fall is more serious than that in the spring.

Fourth, prevention and control measures

1. Agricultural control: Reasonable layout to avoid continuous cropping of cruciferous vegetables; after harvesting, vegetables should be treated in time for defoliation or immediate ploughing in order to eliminate the source of insects.

2. Physical control: Plutella xylostella has phototaxis. In the adult stage, a black light lamp is installed every 0.67 hectare (10 mu), which can induce a large number of diamondback moths and reduce the insect source.

3. Biological control: The use of bacterial insecticides, such as BT emulsion, can cause a large number of larvae of diamondback moth to die.

4. Chemical control: Permethrin, cypermethrin, deltamethrin, thiazole nitrile and other agents can be sprayed and controlled.