What is the law of occurrence of the hazards of walnut flat leaf beetle? What are the prevention mea

Walnut leaf beetle is a serious leaf-eating pest that consists mainly of three subspecies, including the black-breasted subspecies, the light-footed subspecies, and the specific subspecies. With the development of the walnut industry, the harm of walnut leaf beetles is becoming more and more serious. The following is a detailed introduction to the hazards, occurrence rules and prevention measures of walnut leaf beetles.

1. Hazards:

Walnut flatleaf beetle mainly to adults, larvae gather to feed on the leaves to produce damage, explosive and destructive, the early damage to the leaves will bite into the net or there is a gap, the outbreak can eat all the leaves in a short period of time, only the main vein remains, causing the leaves to scorch, the branches wither, from a distance like fire, causing the plant to decline in the current year, conducive to the invasion of secondary pests such as Aspergillus, resulting in a reduction in walnut yield, and the harm for many years can lead to the death of the whole plant.

Second, the law of occurrence:

The spread of the walnut leaf beetle relies on both natural transmission and artificial transmission, with artificial transmission mainly through the artificial transfer of seedlings and scion, while natural transmission relies on the flight ability of the walnut leaf beetle. Adult walnut leaf beetles generally lay eggs on the back of the leaves in early April and are unlikely to be spread by scion, mainly through human transport of walnut seedlings or transplanting large trees. Adult juglans leaf beetles are capable of flying short distances and have some natural transmission capacity.

In early April, when the temperature is above five degrees, the overwintering adults come out of the stinging activity, the temperature rises in June, and the phenomenon of "overwintering" appears, and in October the temperature drops and "overwinters" on the trees. "Overwintering" walnut leaf beetles in hidden places such as dead branches and fallen leaves. Making it harder to find a place to sleep.

This insect is very reproductive, although the density of insects can be quickly suppressed by chemical spraying, but because the walnut planting area is mostly mountainous, and the walnut planting area is more scattered, widely distributed and scattered, it is difficult to get rid of it several times.

3. Prevention and control measures:

Chemical control. During the period of high incidence of adults and larvae (April to May), the use of insecticides such as 10 times imidacloprid wettable powder 1,000 times, 40 oxaliplatin 1,000 times, chlorpyrifos 1,000 to 1,500 times can reduce population density in a short time.

Biocontrol. In areas where larvae are concentrated, Clostridium perfringens is effective against larvae of leaf-eating pests but not adults. Natural predators such as ladybugs and bugs are protected and utilized.

Physical control. Taking advantage of the phototropism of adults, black light is used to trap and kill at night.

Generally, with the growth of crops will become more and more serious, to use pesticides and fertilizers in time, we must control the density of pests, and effective measures should also be taken, and chemical spraying can be selected.

Generally, the early stage is relatively simple, and the situation in the later stage will become more and more serious, so we must do a good job of protection, use pesticides and fertilizers regularly, pay attention to soil fertility, and do a good job of watering and fertilizing.

The hazard of walnut leaf beetle is explosive and devastating, and the occurrence law mainly depends on natural transmission and man-made transmission. 2. Biological control ; 3. Physical prevention and control.

Walnut flat leaf beetle is also known as walnut leaf beetle and goldenrod insect.

1) Symptoms of harm.

Adults and larvae feed on the leaves, eat into a network or missing, and even eat all the leaves, leaving only the main vein, which resembles fire, seriously affecting the tree potential and yield, and some even die of the whole plant.

2) Shape is circular.

Adults are about 7 mm long, flattened, slightly rectangular, bluish-black to black. The dots on the dorsal plate of the prothorax are inconspicuous, yellowish-brown on both sides, and the dots are thick. The wings are carved coarsely, with longitudinal columns and wing surfaces, with longitudinal horizontal stripes.

Egg yolk green. The body is black, and the aging time is about 10 mm. The first segment of the chest is pale red, and the following segments are pale black.

Pupae inky black, thorax with grayish-white lines, abdomen 2nd and 3rd segments yellowish-white on both sides, back **grayish-brown.

3) Habits.

One generation occurs in a year. Adults overwinter in ground cover or in the cracks in the skin at the base of the trunk. In North China, the adults began to be active in early May, and in Yunnan and other places, they fed on the leaves in early to mid-April, and laid eggs on the back of the leaves, and the larvae gathered on the back of the leaves to feed after hatching, leaving only leaf veins.

May and June are the damage period for adults and larvae at the same time.

4) Prevention and control methods.

In winter and spring, scrape the old warped bark at the base of the trunk and burn it to remove the overwintering adults. 4 When the adults go up the tree in May, they are booby-trapped with a black light. In April and June, spray 10% cypermethrin 8000 times solution to control adults and larvae, and the control effect is good.

Walnut leaf beetle belongs to the order Coleoptera, leaf beetle, also known as walnut goldenrod. It is widely distributed, and it is seriously occurring in mountainous areas such as Xinglong and Qianxi in Hebei. The main hosts are walnut, bubble walnut, maple poplar, etc. Adults and larvae feed on mesophyll in clusters, and the affected leaves are reticulated and soon turn black and die.

Morphological characteristics] Adult: 7 8 mm long, flattened and slightly rectangular, clear blue to purple-blue. The head has coarse notches.

The notches on the dorsal plate of the anterior thorax are inconspicuous, yellowish-brown on both sides, and the dots are stout. The elytra are coarsely inscribed, longitudinally arranged on the surface of the wing, with longitudinal and horizontal ribs, the base of the wing is more raised on both sides, and the edge of the wing is folded.

Egg yolk green.

Larvae: The first instar larvae are black, the mature larvae are 10 mm long, the carcass is dark yellow, the dorsal plate of the prothorax is pale red, and the dorsal plate of the later segments is pale black.

Pupa: black-brown, with grayish-white lines on the thorax and a larvae-shed skin at the end of the abdomen.