What are the hazards of armyworm? How to prevent and cure?

Recently, the number of adults of armyworm has increased sharply in Jianghuai, Huanghuai and North China, according to the Disease and Pest forecasting Office of the National Agricultural Technology Center. Jiangyan in Jiangsu Province and Changdao in Shandong Province reported that the daily number of moths trapped by single lights reached tens of thousands, and the number of insects trapped in Northeast China was significantly higher than that in the previous year. So, what are the hazards of armyworm? And how to carry out prevention and control? Let's take a look at it in detail.

Armyworm has these hazards!

Armyworm belongs to Lepidoptera Noctuidae, also known as razor worm, colorful worm, armyworm, night burglar. It is an important migratory pest on corn and other crops in China, which has the characteristics of clustering, overeating and migratory harm, which caused serious harm to autumn crops in different regions a few years ago.

In serious cases, corn seedlings are often eaten up overnight, resulting in lack of seedlings, broken ridges, or even ploughing and replanting.

This year, the first-generation adults are characterized by early peak time, wide occurrence area and high local insect population, and the second-generation armyworm has small plants and weak resistance in the harmful period, especially once the northern spring corn is eaten, it is in danger of destroying the seeds. delay farming time and affect the safety of autumn crop production.

The habits and rules of armyworm

The larvae are mostly active in the morning and evening, that is, from sunrise in the morning to 10:00 in the morning and around evening. They are often in danger of mass migration, so they are also known as "marching insects".

The body color of the larvae varies with the instar, density and food. The young larvae feed on the tender leaves, and the body color is green to grayish green; the second instar larvae only eat the mesophyll; after the third instar, most of the leaves are eaten up along the leaf margin, and when the damage is serious, only a very short midvein remains; the fourth instar larvae are black or grayish black, the mature larvae are 38 mm long, the head is yellowish brown, there is an "eight" longitudinal shape, and there are 5 longitudinal stripes on the back.

Armyworm is a moderately warm and humid insect, with the optimum temperature of 19: 23 ℃ and the optimum relative humidity of 50-80%. Like to eat Gramineae crops and weeds, food intake increases with age, five to six years old is overeating stage.

In general, irrigated land, fields with multi-fertilizer and close planting of wheat in the previous crop, and fields with long symbiotic period of wheat and corn are beneficial to adult oviposition and larval growth because of sufficient food source and suitable temperature and humidity. Most of the insects lay eggs in the withered and yellow leaf tips and leaf sheaths in the middle and lower parts of wheat, and a single female laid 1000 eggs.

The adult has a strong flying ability and has the characteristics of long-distance migration.

Technical measures for the control of armyworm

1. Trapping and killing techniques for adults:

(1) sexual attractant. With a dry moth trap equipped with armyworm sex attractant, one plug per mu was hung in the field.

(2) insecticidal lamp. During the period of adult occurrence, insecticidal lights are placed in the field. The distance between the lights is 100 meters, and the lights are turned on from 8: 00 p.m. to 5: 00 a.m. The use of concentrated continuous tablets has significant control effect.

two。 Larval control techniques:

(1) Biopesticide:

Spraying Bacillus thuringiensis (BT) preparation at the initial stage of armyworm egg hatching, it should be noted that the fields near the mulberry field can not be used, and the young larvae can use diflubenzuron.

(2) Chemical pesticides:

When armyworm larvae are found, it is best to choose quick-acting insecticide spraying, such as permethrin + metoprolol salt, flurosemide + cypermethrin and so on. These agents are basically contact killing and poison feeding, spraying to the location of the armyworm habitat. Chlorobenzamide, diflubenzuron, hydrazine and other slow-acting insecticides, it is best not to use alone.

In the process of corn armyworm control, corn armyworm should be controlled before the third instar as far as possible. The control time generally chooses the high incidence time when the larvae feed in the morning and evening, and the corn heart leaf is selected as far as possible. Pay attention to personal protection when spraying and strictly prevent the occurrence of poisoning accidents.

In addition, armyworm has the habit of landing in shock. When administering medicine, we should pay attention to spraying the surface to eliminate the "bugs" that fall on the ground. At the same time, we should also spray weeds along the roadside, and strive to eliminate the "extrajudicial insects" that inhabit there.