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Tea caterpillar , Euproctis pseudoconspersa Strand , is an insect of the genus Lymantriidae of the genus Lymantriidae. It is distributed in all tea-producing provinces in China and is an important pest in China's tea regions. It is mainly harmful to tea, but also to oil tea, citrus and so on.
The young larvae bite the old leaves of the tea tree into a semi-permeable membrane, and later bite the young shoots into leaves into a missing moment. Larvae are infested in clusters, often gathering in dozens to hundreds of heads on the back of the leaves to feed. When severe, the leaves of tea trees are eaten up. In addition to harming tea trees, it is also harmful to oil tea, camellia and so on. The larvae feed on the leaves, and in severe cases, they eat all the buds, bark, flowers and young fruits. Tea caterpillar larvae and adult insects have poisonous hairs and scales on their bodies, which are red, swollen, painful and itchy after touching human skin, affecting agricultural operations.
What does a tea caterpillar look like?
01
ovum
It is round and pale yellow. Adults lay their eggs in a lumpy, oval shape, covered with yellow-brown fur shed from the end of the female moth's abdomen, mostly on the back of the leaf.
02
larvae
The body color of the larvae gradually changes from light yellow to yellowish brown with the age of the insect, the body shape is cylindrical, the body length of the elderly larvae is about 20 mm, yellowish brown, there are melanomas on the back and sides of the body, and the tumor is clustered with yellow poisonous hairs.
03
chrysalis
It is about 9 mm long, conical, yellow-brown, with short hairs and hook-like tail spines. There is a yellow silk cocoon on the outside, the cocoon is about 13 mm long, yellow-brown, oblong-oval, pasted on the branches of the tea tree, with long poisonous hairs on the surface.
04
imago
Female moths are 6 to 13 mm long, have a wingspan of 20 to 30 mm, and have a yellowish brown body. The male moth body is dark brown. The forewings have 2 pale bands in the center and 2 black dots on the tip of the wing. The female has a thicker abdomen than the male moth and has yellow-brown villi at the end.
What are the dangers of tea caterpillars?
The larvae feed on the leaves, and the parts that are eaten are absent, and in severe cases, they will eat the leaves. When it occurs for a long time, it is eaten together with buds, shoots, bark, flowers, fruits, etc. The affected tea plants not only suffered yields, but also the growth of tea plants was difficult to recover for a while.
In addition, in addition, all forms of insects have poisonous hairs, which will itch and swell when touching the skin of the person.
Tea caterpillar life habits
Algebra varies from place to place. It usually occurs in 3 generations per year, overwintering in egg masses on the back of old leaves. Each generation of larvae occurs from April to May, June to July, and August to October. It is generally heavy in spring and autumn.
Adult insects are mostly feathered from the afternoon to before dusk, lying quietly on the back of the leaves between the branches of the tea bush during the day, quickly flying away or falling to the ground to fake death after being frightened, and began to be active after dusk, active at night, and the most active from 19:00 to 23:00. There is phototropism, and the male moth is more sexual than the female moth. Eggs are laid on the same or the next day after feathering, and eggs are laid on the same day or the next day after mating. The eggs are laid in chunks on the branches of the tea bush and on the back of the lower leaves. Each female moth lays 50 to 200 eggs, and as many as 300. In general, wintering eggs are mostly produced in warmer tea gardens, and non-wintering eggs are often laid in tea gardens with lush branches or shades.
The larvae are afraid of light and high temperatures and are neatly arranged when migrating. Larval clusters are strong, especially in those aged 1 to 3 years. The larvae mostly hatch from morning to noon. The peak incubation period is generally about 5 days after the initial incubation. 1-2 instar larvae often gather tens to 100 heads on the back of the leaf near the egg mass, bite the epidermis and mesophyll of the leaf, leave the epidermis, and the damaged area is translucent reticular membrane spots, and then turns grayish-white. After the 3rd age, the amount of food increased, and began to migrate to the upper branches and leaves of the tea bush to feed, often spitting silk and knotting thin nets, and spitting silk after being frightened. After 4 to 5 years of age, the amount of food increased greatly, and the leaves, buds, bark, flowers and fruits were eaten. In case of alarm, stop eating, and swing your head to the left and right, spitting out yellow-green juice. After the 6-7 instar larvae mature, they stop feeding, crawl to the cracks in the inter-root soil of the tea tree, and form cocoons under the dead branches and leaves, and there are more pupae in the dark and moist place.
Factors influencing the occurrence of tea caterpillars
One is the source of insects. Overwinters in egg clumps in the tea plant, near the main vein on the back of the lower old leaves.
The second is climatic factors. Heavy rains can cause large numbers of larvae to fall to the ground and die. In the adult stage, in the event of high temperature and drought, the feathering rate is low and the spawning volume is small.
The third is the cultivation factor. In general, tea plantations with extensive management, overgrown weeds and intercropping high-pole crops occur more heavily. The first generation of larvae are often more yangpo tea gardens, and the second and third generation larvae are more shaded or shaded tea gardens.
Fourth, natural enemies. The main natural enemies are the tea caterpillar black egg bee, the red-eyed bee, the tea caterpillar velvet cocoon bee and so on.
Tea caterpillar detection method"
1 Prevention and control timing prediction
The peak period of feathering of adults in the overwintering and non-wintering generations is pushed backwards to add the average developmental period of local contemporary eggs, and then the calendar of 1 instar larvae, that is, the peak period of 2-instar larvae, that is, the appropriate period for the control of contemporary larvae.
2 Period forecasting method
Before each generation of eggs begins to hatch, 200 egg blocks are scattered and marked in representative tea gardens, and the number of hatched egg blocks is checked day by day or every other day, and when the hatching rate reaches 50% into the peak period, the 1-3 year old larval period is added backwards, that is, the appropriate period for prevention and control.
3 Sexual attraction and lamp seduction prediction method
Sexual attraction (active ingredient is (R)-10,14 dimethylpentadecanosan isobutyl ester) and lamp temptation (wind suction LED insect lure lamp) tea caterpillar detection effect, when the sexual attraction and lamp induce the moth for the most days, that is, the moth peak period, plus 1-2 days of pre-spawning and local contemporary egg calendar period of 7-15 days, that is, the larval incubation period.
4 Tea caterpillar larval development calendar prediction method
The developmental calendar of tea caterpillar larvae at different temperatures was determined, and between 15-27 °C, the developmental period of larvae shortened with the increase of temperature. For example, the appropriate period for the control of the 2nd generation larvae = June 15 on the peak date of the moth + 1-2 days in the pre-spawning period + 12-15 days in the egg calendar period + 3-4.5 days in the 1st instar larval stage + 4 days in the 2nd instar larval stage + 4-5 days in the 3rd instar larval stage = June 15 + 24-30.5 days = July 9 to 16.
5 Temperature accumulation prediction method at the starting point of development of each insect stage
Ovary stage C=12.53 2.15(°C), K=191.00 36.21(°C.d); Larval stage C=6.16 2.14(°C), K=820.24 99.39; pupal stage=4.89 0.36(°C), K=365.28 6.85(°C.d); Generation C=7.90 0.38(°C)K=1340.36 123.55(°C.d). The use of meteorological data in various places to measure the algebra of occurrence in various places is basically consistent with the actual situation.
6 Regression prediction
A generation of tea caterpillars began to predict from April 1. If the monthly average temperature in March 2017 is 10.87 °C, then =54.63-2.8596× 10.87=23.54, that is, the first generation prevention and control period in 2017 is April 24.
7 Occurrence hazard trend prediction
The number of egg blocks per hectare > 6000 or the number of residual elderly larvae in the previous generation > 15000, indicating serious occurrence; the number of egg blocks per hectare > 750-6000, or the number of residual elderly larvae in the previous generation > 3000-15000, indicating a moderate and locally heavy occurrence; the number of egg blocks per hectare < 750 or the number of surviving elderly larvae in the previous generation < 3000, indicating a light occurrence.
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What are the prevention and control measures of the European standard tea garden
The key to the control of tea caterpillars is to eliminate the larvae before 3 years of age, and the following four aspects of prevention and control methods are commonly used.
Agronomic control
Combine deep and shallow farming with the removal of dead leaves and weeds from the garden to eliminate cocoon pupae. In particular, the soil is cultivated in the pupal period, and the soil is more than 6 cm thick at the rhizosphere, and slightly pressurized to prevent the feathering of adult insects from emerging. In the 1st to 2nd instar larval stage, the larvae of the cluster are cut off and destroyed intensively. In the autumn and winter dry grass season, artificial egg blocks are found and burned in a concentrated manner.
Physical control
One is light booby-trapping. During the feathering period of adult insects, solar insecticidal lamps are installed in tea gardens for booby-trapping, and the effective area of solar insecticidal lamps in mountainous areas is 2hm2.
The second is the booby trap of the yellow plate of the armyworm. In the tea garden, sticky insect yellow plates are inserted to trap adult insects that are active during the day, and in mountainous areas, according to the specifications of 3m × 3m, and about 15 cm higher than the tea plants, the yellow board is inserted.
The third is sexual pheromone booby-trapping. Set up tea caterpillar sex pheromone traps to trap adult insects.
Biocontrol
The first is to protect and use natural enemies to control harm. Protect natural enemies such as black egg bees, red-eyed bees, tea caterpillar velvet cocoon bees and other natural enemies in tea gardens, and artificially release commercialized parasitic bees.
The second is the prevention and control of obligate pathogenic microorganisms. Tea caterpillar karyotype polyhedral virus, Thuringiensis, white zombie, green zombie, etc. were selected for prevention and control.
The third is to protect predators such as catching spiders and birds.
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