Recently, a number of growers have consulted how the gray elephant armor can not die, and it will be beaten again for a few days.
Grey weevil
Sympiezomia citre Chao, also known as citrus gray elephant, citrus weevil, gray scale weevil, mud-winged weevil, commonly known as orange monkey, pointed tortoise, proboscis and so on. It is distributed in Guangdong, Guangxi, Fujian, Zhejiang, Jiangxi, Hunan, Sichuan, Guizhou, Shaanxi and other citrus producing areas.
A number of gray weevils gather as harmful branches and leaves
First, the fruit surface and leaves are missing
Adults bite into new leaves of the spring shoots, causing missing carvings or holes, and the leaves of young citrus spring shoots are particularly affected. It also bites on young fruits, causing the fruit surface to be dented and lacking in carving, or leaving scars on the fruit surface. Serious harm leads to fruit loss.
The grey weevil feeds on young fruits and leaves
Second, get to know the grey weevil
The female is 9.3–12.3 mm long, the male is slightly smaller and has a body length of 8–10 mm; the body is covered with off-white or grayish-brown scales, dull; the head is thick and wide, the back is black, there are 3 longitudinal grooves on the surface, the central 1 groove is concave, and the lateral grooves are shallow; the compound eyes are black; the dorsal plate of the anterior thorax is ovate, with a thin longitudinal groove in the center, and the entire thorax is covered with rough and protruding dots; the elytra are covered with black-brown, gray-brown mixed markings and 10 dots longitudinal columns; the hindwings are degenerate and have no ability to fly. The male has a narrow and long abdomen with unconstricted and bluntly conical ends of the elytra; the female has an enlarged abdomen, a broad and short thorax, and the end of the elytra is constricted and sharp.
The ovoids are cylindrical, slightly flattened, 1.1–1.4 mm long, colostrum white, posterior purple-grey.
The larvae are milky white to pale yellow, 11.0–13.5 mm long when mature, pale yellow in the head, and 11 segments of the body segments are recognizable.
Pupae are pale yellow, 8–12 mm long, with the head tube curved towards the chest, such as pincers, the dorsal plate of the anterior thorax is raised, the posterior margin of the middle thorax is slightly concave, and there are 6 pairs of short bristles on the back of the abdomen; 6 pairs of bristles are arranged horizontally in each segment of the abdomen, and there are 1 pair of spines on both sides of the end, black-brown.
Third, 1 generation / year of adult insects are prone to suspended animation
Occurs 1 generation a year, with adults overwintering in the soil, and some orange areas overwinter with adults and a few larvae. Overwintering adults emerge from late March to mid-April of the following year, crawling on the ground after emerging, climbing up the canopy along trunks or drooping branches, and commonly 3-5 heads together, biting, mating and laying eggs on the spring shoots of the year.
From mid-April to early May, the damage is severe, and when the leaves are ripe, they turn to young fruits. Adults are pseudo-dead and sensitive, and when a person approaches, they turn to the other side of the leaf to avoid sight and fall to the ground if alarmed. May is the peak of spawning, the eggs are laid between the two leaves overlapping, the eggs are monolayer adhesion into blocks, different sizes, after laying eggs, with the secretion of colloids to glue each other. Each female can lay hundreds of eggs in her lifetime, with an egg laying period of 5-7 months and an average of 95 days.
After hatching, the larvae fall into the soil for 10-50 cm and feed on the fine roots and humus of the plant. The larvae are 5-6 years old, mostly 6 years old, and the larval stage is up to 372-400 days. The old mature larvae build oval pupae chambers in the soil and pupate in them.
In Shaoguan, Guangdong Province, it was found that there were peach trees or plum trees planted before the orchard was established, or there were peach and plum trees around the orchard, and they had lost control, and the gray weevil would occur more seriously.
Iv. Chlorpyrifos + high-efficiency cypermethrin or thiamethoxine spraying to kill adult insects
(1) In winter, the soil layer under the canopy is deeply turned over 15 cm, destroying the soil chamber; after the adult insects are on the tree, they use their pseudo-death to lay plastic film on the ground, and then shake the branches to collect and destroy.
(2) When the adult insects are unearthed, spray 50% octylthion emulsion 200 times liquid, or 48% chlorpyrifos emulsion 1200 times liquid, or quinothion, or permethrin agents on the ground. The canopy is sprayed with 50% octyl thiophos emulsion 1000-1500 times liquid, or chlorpyrifos, or quintilion, or propyl bromide, or permethrin, to kill and repel adult insects. Chlorpyrifos + thiamethoxam can also be used.
(3) Spraying to prevent and control gray weevils, always appear poor effect, it is best to spray the canopy, the ground also sprinkled with medicine, because when spraying elephant nails are easy to fake death fall to the ground, spraying the ground can be sprayed to the insect body, so that the agent can play an effect.
Thank you to Teacher Cai of Yangcun Overseas Chinese Citrus Farm Citrus Research Institute for his support of the manuscript!
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