Occurrence and Control of Shield scale in Pear Orchard

Shield scale in pear orchard belongs to Homoptera, Coccidae, which is difficult to control on pear trees. In recent years, through observation, we have basically mastered the occurrence law of pear orchard shield scale in Korla area, and through several years of control experiments, we have found a set of effective control methods.

I. characteristics of hazards

The pear orchard scale mainly harms the fruit trees and trees, and the fruit trees mainly harm the branches, fruits and leaves of pears, apples, dates, grapes, apricots and plums. Many scale insects are often concentrated on the branches, and the injured parts show red round spots. In severe cases, the cortex burst and even withered. After the fruit is damaged, there is a red ring around the insect body, and the worm often shows a red, which in serious cases causes the fruit surface to crack and the commodity value to decline. Red fruit worm body under the fruit surface can not be colored, wipe off the worm body, the fruit surface there are many small spots, so that the fruit loses its commercial value.

Second, morphological characteristics

1. Adult worm

The female adult is covered under the waxy shell with a slightly round, orange-yellow body, 0.9-1.2 mm in length and 0.8-1.2 mm in width. The mouthparts are filamentous, located in the center of the ventral surface, with verrucous antennae and degenerated eyes and feet. The body shell is round gray, the shell surface has a wheel pattern, the center is slightly raised, the shell point is yellow or reddish brown, located in the center of the body shell. The male adult is 0.6 mm long, the wing is white and translucent, the wing vein is degenerated, the wingspan is 1.2 mm, the body is orange-yellow, the head and chest color is dark, the eyes are dark purple, and the mouthparts are degenerated.

two。 Nymph

The early instar nymph is 0.2 mm long, oval, orange-yellow, antennae, mouthparts and 3 pairs of feet are well developed. The oral organ is 2 times longer than the body length, curved under the abdomen, and there are 2 long hairs at the end of the tail. The peeling of the first instar nymph is the 2nd instar nymph, and the male and female can be distinguished at this time. The antennae, feet and eyes of the female disappeared, and the shell was round, while the shell of the male was shield-shaped and pupated under the shell.

3. Pupa

The pupa is 0.6 mm long, yellowish, conical, antennae, feet and wings.

Third, occurrence regularity

2-3 generations a year, overwintering with 1-2-year-old nymphs on the branches. The sap continues to harm when it flows in the spring of the following year. Generally speaking, the overwintering insects begin to move and peel in the first ten days of April, and the female worms begin to expand and the males pupate in late April. The first adult appeared in the first and middle of May, the second male emerged in the middle of July, and the late July was the last stage. The first generation of viviparous nymphs began from the end of May to the beginning of June, the second generation nymphs appeared at the end of July and the beginning of August, and the third generation nymphs appeared from the end of September to the beginning of October. The vivid nymphs crawled out of the shell after a period of time, and they were very lively and fast. After selecting the appropriate parts on the branches and fruits and inserting the mouthparts into the plant tissue to take nutrients, they were fixed. After 1: 2 celestial bodies secreted white wax and gradually formed a shell, gradually turning grayish yellow. After peeling for 10 to 12 days, the antennae, feet and eyes disappeared, and the males and females differentiated. After peeling for 3 times, the male worm pupated and emerged as an adult. After peeling twice, the female becomes an adult and gives birth after mating. The female likes to be on the sunny side of the branches. The generation that occurs in summer is mostly parasitic on the back of leaves and fruits. Most male worms are parasitic along the main vein on the sunny side of the leaves. The last generation of nymphs at the end of August peeled into 2-year-old nymphs after 10 days and overwintered on the branches.

IV. Comprehensive prevention and control methods

1. Strict quarantine

Seedlings, branches, scions, fruits, etc., should conscientiously do a good job in quarantine during transportation to prevent spread.

two。 Artificial disinfestation

Combined with winter cutting to remove worm-carrying branches, at the same time can be brushed with a cleaning ball or with a copper wire brush, although labor-consuming, but more effective.

3. Protect natural enemies

The natural enemies of the pear orchard scale are ladybugs, lacewings, parasitic wasps and so on. As long as the natural enemies are well maintained, the pear orchard shield scale will not cause huge losses to production. If the insecticide is not used properly, it will kill a large number of natural enemies, which will cause great occurrence and cause huge losses to the production of fruit trees.

4. Drug prevention and treatment

Due to the irregular generation and serious overlap in pear orchard, several key prevention and control periods should be mastered: before ① germinates in late March, when overwintering nymphs feed, spray 5-6 Baumedushi sulphur mixture. In this period, it is very effective to kill nymphs on the dry polish of pear. During the growth period of ②, 40% speed culling 1000 times liquid, Guosheng 500 times 1000 times liquid, 48% Lesbon 1000 times solution can be sprayed in the first and middle of June and August respectively, and if serious happens, it can be sprayed again every 7 days and 10 days. After fruit harvest in ③ from the end of September to the beginning of October, spraying 40% dimethoate 1000 times and 80% dichlorvos 1000 times could reduce the number of insect population.