What are the main pests of longan and litchi and their control?

1. Longan litchi borer, including Longan borer, Litchi stem borer and Litchi borer, is one of the most common pests in longan and Litchi producing areas in China. Young insects eat litchi, longan twigs, young leaves, flower spikes and fruits, which will weaken longan trees in severe cases, affect the formation of fruiting mother branches in the next year, and also cause a large number of flowers and fruits to fall. Borers and sea wheat moths will also eat young fruits and mature fruits, which will reach "ten fruits and nine fruits" seriously, leaving a lot of insect droppings to affect fruit quality.

1989 A new species-Longan Sea Wheat Moth was discovered. Litchi stem borer and litchi sharp moth are two related species of Lepidoptera, named J.D.Bradley 1986. Usually mixed with longan and litchi. In the past, people have long confused these two insects into one species: Chen Wenxun (194 1) and Qian (1955) were mistaken for Acroerops cramerllen. Cocoa moths have not been found in longan and litchi producing areas in China. Yao et al. revised it in 1990 and named it litchi stem moth and litchi sharp moth respectively. The three kinds of moths, longan and litchi, are subtle, which often lead to a lot of harm if they are not careful. The three kinds of adults and larvae are similar in morphology and some harmful habits, so we must identify them carefully to avoid mistakes.

(1) Hypitima longana e.sp.nov (see Figure 2-52) is a new pest, feeding on branches, ears and young fruits, belonging to Lepidoptera, Mothidae and Mothidae. According to the survey, longan producing areas such as Fujian, Guangdong and Guangxi are more common, and some areas are seriously affected. Longyan Garden in Xianyou, Fujian (6-9 years old), the damage rate of autumn shoots is 18.2% ~ 30.2%, and the damage rate of new shoots in Chengyuan Garden in Fuzhou is 4 1. 1%. It mainly eats xylem of the new shoots of longan, destroys the vessel tissue, leads to imbalance of water metabolism, and causes the same cluster or ghost ear symptoms as longan ghost broom disease. It shows that the tender leaves are curled after eating the tender branches, and the flower spikes are dense in summer and autumn (the main ghost broom is the mother branch of longan), and the flowers are bloated and fat, which leads to the weakness of the tree and reduces the yield of that year. Judging from the severity of the damage in longan producing areas in China and the fact that the insect is newly discovered, the masses still don't know much about it. Therefore, longan gall midge should be a noticeable pest in longan producing areas in China.

Figure 2-52 Morphology of Longan at Different Development Stages

1 .adult 2. Egg 3. Larva 4. pupa

① Morphological characteristics: adult: 3.5 ~ 5 mm in length and 10 ~ 12 mm in wingspan. The head is gray and the top of the head is slightly brown; Large scales are wrapped in the middle of the back from both sides and protrude backward above the front chest collar. The compound eye is black and the beak is densely covered with white scales. The anterior wing is lanceolate, and the secondary leading edge vein (SC) extends to the center of the leading edge. Eggs: oval, light yellow at first, then orange. Larvae: mature larvae are 7 ~ 9 mm long and yellow-white. Pupa: 5 ~ 6 mm long, yellow-brown, densely covered with light-colored short hair, and the hair at both ends of the head and tail is the most obvious.

② Living Habits According to the observation of the Institute of Plant Protection of Fujian Academy of Agricultural Sciences, there are five generations in Fuzhou, with overlapping generations. But every generation of moths has an obvious peak period. The mature larvae overwinter in the branch hole and pupate from late March to early April of the following year. The overwintering moth blooms from late April to early May, and the first generation larvae (from late April to late June) harm spring shoots and flower spikes, affect germination and cause small flowers. The second generation moth has an obvious peak period from mid-June to late August, and the second generation larva (from late June to mid-August) harms summer shoots and summer shoots, which has a great influence on longan yield in the following year. The third generation moth blooms from late August to early September, and the third generation larva harms autumn shoots (from early August to mid-September). The fourth generation moth bloomed in mid-September; The fourth generation larvae (from mid-September to late June of 10) harm autumn shoots and winter shoots; The fifth generation moth appeared in early October of 65438+1mid-October. The sixth generation larvae (65438+1mid-October) damage winter shoots, and overwinter around mid-June165438+1October.

Due to the change of indoor natural temperature in Fuzhou, when the daily average temperature is 265438 0.6℃, the average egg stage is 65438 065438 0.5 days, the larval stage (***4 years old) is 23.5 days, the pupal stage is 65438 065438 0.3 days, and the pre-spawning stage is 3.5 days, which is complete. It was observed that most adults emerged at 8 ~ 10 in the morning and 3 ~ 5 in the afternoon, and the eggs were scattered the next day. Eggs are mostly laid in the gap between the terminal buds of new shoots and the veins on the back of young leaves, or in the cracks in the epidermis of branches. The spawning period is 4-8 days, with an average of 5.5 eggs per female per day, with the highest number of eggs per kloc-0/4. The life span of female adults is 6 ~ 10 years. Eggs usually hatch at 8 ~ 1 1 in the morning, and the newly hatched larvae climb out of the hole at the bottom of the egg. If the egg is laid in the bud, feeding directly from the bottom of the egg is harmful to the tender bud. After the larvae eat into the branches, they generally feed downward, and the injured part forms a tunnel, constantly discharging feces to the outside of the hole. As the worm grows older, the hole becomes bigger, and then

The natural enemies in the egg stage are Trichogramma, predatory mites, midges, thrips and so on. In the larval stage, it has been found that the parasitoids such as yellow-breasted bee and tender bee are all single parasitoids, and the parasitism rate of overwintering larvae is 4.56% ~ 12.9%.

(2) Litchi stem borer (see Figure 2-53)

① Morphological characteristics of adults: wings spread about 9.2 ~ 1 1.5 mm, brown head, white face and filiform antennae. The front wing is gray-black, with two white stripes at the base, a "W" shape consisting of five white twill in the middle, a white stripe at the top and a small black circle at the tip of the wing. The two front wings are "stubborn". The fifth white twill is the orange-yellow area between the black stripes at the wing tip, the middle area is Y-shaped, and the end near the leading edge is silvery white. On the fifth white diagonal line, near the front, there is an approximately triangular black dot. The hind wings are gray-black. There is a black twill on each side of the abdomen. Egg: oval and yellow, with about 10 rows of microprotrusions in the longitudinal direction of the eggshell. Larvae: about 9 mm long, yellow-white, with 3 pairs of chest feet and 4 pairs of abdomen feet (including hip feet). The hip plate is triangular and pointed at the end. Pupa: about 7 mm long, dark. There is a cocoon breaker on the top of the head, and the part of the antenna protruding from the abdomen is twice as long as the seventh to tenth abdominal segments. White and tight membrane cocoons are formed on the leaves.

Figure 2-53 Pedicle Drill

1 .adult 2. Larva 3. Cocoon 4. pupa

(2) Life habit: Chilo suppressalis (Chilo suppressalis) occurs once a year in Zhangzhou, Fujian, with 10 generation, which is harmful to litchi and longan, in which15 generation mainly harms fruits and 6 ~ 10 generation harms twigs.

There are 8-9 generations of stem borers in Fuzhou, and the first generation feeds on longan, litchi twigs and young fruits from early April to late May. The second and third generations mainly bear fruit in June and July; The fourth generation eats longan fruits and twigs from late July to early August; The fifth, sixth and seventh generations eat new longan shoots from the middle and late August to 1 1; 1 1 The eighth generation and a few ninth generations enter the winter together.

(3) Lychee sharp moth

① Morphological characteristics: The shape of litchi stem borer is very similar to that of litchi stem borer. Adults: wings spread 8.3 ~ 9 mm, head white, tentacles filiform. The front wings are gray and black, and the buttock area is black and white. There is a "W" pattern in the middle, a large and a small round pattern at the wing tip, and it is silvery white near it. The front is orange, with two parallel black twill lines extending from the back to the front, dividing the orange area in two, and the tail is dark gray. There is a dark brown twill on the side of the abdomen. Eggs: oval, milky white to light yellow, with reticulate patterns on the eggshell. Larvae: about 8 mm long, pale yellow, slightly flat, with 3 pairs of chest feet and 4 pairs of abdomen feet (including hip feet), weak; The hip plate is nail-shaped, and there are several bristles at the rear edge. Pupa: about 5 mm long, dark, with a cocoon breaker on its head. The part of the antenna protruding from the ventral end is as long as or slightly longer than the seventh to tenth ventral nodes. White membrane cocoons are formed on the leaves.

(2) Living habits in Fuzhou, Fujian Province, occur for 5-6 generations a year, which harms the branches, leaves and spikes of longan and litchi. Larvae dive on the leaves, and when it is a little longer, it will eat into the veins or tips of the leaves, and it will break holes and excrete feces. The main damage generation (the third to the fifth generation) harms summer and autumn shoots from August to 10 (the next year's fruiting branches), especially in early September, when the larval peak often causes serious damage to the autumn shoots of longan and litchi, the leaves often turn brown, and the whole tree is seriously smoked like fireworks. Larvae overwinter in winter buds and veins.

In order to clarify the similarities and differences of the harmful habits of three longan stem borers, Table 2 compares them as follows:

Comparison of damage habits of three fruit-boring pests, longan and litchi.

(3) Control methods: Longan litchi stem borer, litchi stem borer and litchi sharp borer usually occur at the same time in a longan and litchi orchard, and their damage habits are the same, mainly using larvae to bore young leaves, twigs, flowers and fruits. Therefore, as long as all localities control the most serious borers according to the occurrence regularity, population changes and spatial distribution of the three borers in longan and litchi orchards, good results can be achieved in controlling the other two borers at the same time:

Controlling winter shoots and reducing insect sources: According to the survey, among the winter shoots taken from longan orchards in Fuzhou and Xianyou in the middle and late of 1 1 0, the egg shoot rate of Hymenolepis longan and two fine moths is as high as 35.7% ~ 53.8%, and the winter shoots are many pests (such as moths, foot moths, etc. ) Overwintering.

Pesticide control: First of all, according to the characteristics that most eggs of longan and two kinds of moths are laid on tender branches and leaves, the occurrence period should be predicted according to the phenology of different cultivated varieties in longan and litchi orchards, that is, in the bud stage of new shoots, the amount of eggs on the terminal buds and leaves of tender branches should be checked every 2-3 days. When the amount of eggs laid is obviously increased compared with the last time, directional spraying should be used for prevention and control, and the egg laying rate of fruit trees should be checked 40 days before harvesting. Secondly, the larvae are borers, and the main targets of pesticide control should be eggs and newly hatched larvae. It is advisable to use pesticides or ovicides plus systemic pesticides. The recommended pesticides are: 1% methomyl 3000 times, 5% carbaryl 1500 times, 40.7% Robam 1000 times, 2.5% triamcinolone acetonide 3000 times, etc. In order to improve the efficacy and avoid premature drug resistance, these four different types of pesticides should be used alternately.

Protection of natural enemies in larval and pupal stages: Parasitic bees have been found, including Blasmus sp., Clelomus sp. and Apanre-les sp. , Phaeogenes sp. and so on. These are effective natural enemies of Hymenoptera longan or Hymenoptera. The natural parasitism rate of Hymenoptera is11.2% ~15.6%, and Hymenoptera flavipectus is 12.9%, which can control the occurrence of Hymenoptera and Hymenoptera to some extent and should be protected and utilized to avoid parasitic bees.

2. Litchi stinkbug (see Figure 2-54) belongs to Hemiptera, stinkbug family. Also known as litchi stinkbug, commonly known as Shibei and smelly stinkbug. It is an important pest in longan and litchi producing areas, distributed in Fujian, Taiwan Province, Guangdong, Guangxi, Yunnan, Guizhou and other provinces (autonomous regions) and countries in South Asia and Southeast Asia. It is very harmful to litchi and longan. Adults and nymphs suck the buds, twigs, spikes and young juice of litchi and longan, which leads to the loss of flowers and fruits, and often leads to the loss of fruit yield.

Figure 2-54 Litchi stinkbug

1 ~ 5. 6 larvae per age. Adult 7. egg cluster

(1) Morphological characteristics of adults: 24 ~ 28 mm long, shield-shaped, yellowish brown, with white wax powder on the chest and abdomen. Antenna 4 node, dark brown. Front chest leans forward downward; Odor glands open near the front of the lateral plate of the back chest. The back of the abdomen is red, and there is a longitudinal seam in the center of the seventh abdomen of the female insect, which can be used to distinguish between males and females. Eggs: nearly spherical, 2.5 ~ 2.7 mm in diameter, light green at first hatching, a few light yellow, purplish red near hatching, and often 14 eggs aggregate into blocks.

Lin Quan: * * Five years old, oval; The body color varies from red to dark blue, and the center and outer edge of the abdomen are dark blue. The nymph's smelly glands open behind the abdomen. The body of 2 ~ 5 years old is rectangular. The second instar is about 8 mm long and orange-red; The outer edges of the head, tentacles, chest and abdomen are dark blue; There are two dark blue stripes on the back of the abdomen, which incline outward and forward from the center of the distal segment. The outer edge of the back chest plate extends to the body side. The body length of the third instar is 10 ~ 12 mm, and the color is slightly the same as that of the second instar. The outer edge of the posterior chest is surrounded by the outer edge of the middle chest and the first abdominal segment. The length of the fourth instar is 14 ~ 16 mm, and the color is the same as before. The lateral buds on the dorsal plate of the middle chest are obvious, and the length reaches the posterior margin of the back chest. The fifth instar is 1.8 ~ 20 mm in length, slightly lighter in color, and the wing buds on both sides of the middle chest and back extend to the middle of the third abdominal segment. The first abdomen is very degenerated. When they have feathers, they are covered with white wax powder.

(2) Living habits: Fujian, Guangdong and Guangxi occur once a year 1 generation, and overwinter with sexually immature adults. Overwintering adults cluster, mostly in the shaded, sunny and dense canopy leaves of the host, and also in the roof tiles of houses near the orchard. During the winter, if the temperature rises above 15℃, it will still take the initiative to feed; When the temperature is below 10℃, most branches do not move and suddenly vibrate, which is the best time for artificial killing. When the temperature reached about 16% in early March of the following year, the overwintering adults began to move, feeding on litchi and longan branches or flower spikes, and after sexual maturity, they began to mate and lay eggs, with 14 eggs each time, arranged in blocks. One female lays 5 ~ 10 eggs, with a maximum of 17 eggs. Eggs are mostly laid on the back of leaves, accounting for about 80%, the surface of leaves accounts for 15%, and the ear accounts for 5%. In addition, a few eggs are laid on branches and trunks outside the tree. For the crown, most eggs are laid in the lower layer of the crown. The spawning period of adults is 10 from mid-March to early June, and April and May are the peak spawning periods. The length of spawning period is related to temperature: when the average temperature is about 65438 08℃, the spawning period is 20 ~ 25 days; 0 days at 20.65438+20℃; 65438 02.6 days at 25℃; 9.5 days at 27℃; 7.8 days at 30℃.

Nymphs begin to hatch in early April. The average duration of the first instar nymph is 265,438+0 days, the second instar is 8 days, the third instar is 65,438+00 days, the fourth instar is 65,438+07 days and the fifth instar is 26 days. * * It emerged as an adult after 82 days, but the longest time was 1 16 days. Newly hatched nymphs gather near the eggshell and begin to disperse after a few hours. Nymphs like to perch on the top of branches, prick and suck on branches of flowers and fruits, and suck the juice of twigs, buds, ears and young fruits. It often leads to serious falling flowers and fruits. In case of wind and rain, run away from the back of leaves, shoot smelly liquid for self-defense when disturbed, or fall immediately, and the nymph falling on the ground will fly back to the tree soon. The resistance of nymphs above the third instar increased, and the resistance of the fifth instar was the strongest. New adults appeared at the end of June, and most of them appeared in mid-July. The elderly died one after another after six months, with a life span of 203 ~ 37 1 day, with an average of 3 1, 654, and 38+0 days. Adults like to feed on twigs, flower ears and fruit ears, which mostly occur in longan and litchi orchards. During the period from the fifth instar nymph to the new adult, it eats a lot, accumulates fat, prepares for overwintering and has strong drug resistance. After the adults resume their activities in spring, they undergo reproductive development, vigorous metabolism, fat consumption and natural drug resistance decline, which is the appropriate time for chemical control.

(3) Prevention and control methods

Pesticide control: overwintering adults are sprayed 1 time when mating on new shoots in March, and then sprayed 1 ~ 2 times during the peak period of young nymphs in April and May. Spraying trichlorfon 800 ~ 1000 times, or using 20% pyrethrin 2000 ~ 8000 times, the effect is very good. Generally, the spraying amount per plant is 7.5 ~ 10 kg, and litchi and longan can be sprayed by plane in a large area (20 times of trichlorfon, 30 ~ 37.5 kg per hectare).

Biological control: The natural enemies of litchi in stinkbug are wasps. ，Ooencyrtus corbetti Ferr。 Malay subspecies. O Cleonotto Fife. , salamanders, mantis, birds, etc. , should be protected and used. The control of litchi in stinkbug by wasp has been popularized and applied in Guangdong Province, and there are also experiments and demonstrations in Fujian Province. Introduce or breed enough flat-bellied wasps in early spring, and start to release them at the early stage of spawning, and then release them once every 10 day, * * * three times, generally 500 females per plant each time. When the density of litchi in stinkbug is high, trichlorfon solution should be sprayed to reduce the population density.

Artificial hunting. Kill the overwintering adults, pick the egg pieces and release the nymphs.

First of all, exclude adults. In the low temperature period below 10℃ in winter, the overwintering adults are not very active. Shake the branches violently with the hooked bamboo pole, so that the adults fall to the ground and are eliminated centrally. But adults not only overwinter in trees, this method can only be an auxiliary measure.

Second, pick egg pieces. During the peak spawning period from March to May, eggs were picked from smelly bedbugs and concentrated in simple parasitic bee protectors to protect natural enemies.

Third, release nymphs. Dip a bamboo pole in cow urine or human urine to soak grass, or mash insect juice, or lift a bamboo pole with a rag ball and dip it in kerosene to smoke nymphs, and pile sand or fine soil on the tree head in advance to mix plant ash, so that fallen nymphs are not easy to climb the tree and concentrate on killing.

3. Corngeapsylla sinica Yang et Li (see Figure 2-55) belongs to Homoptera, psyllidae, also known as psyllidae, and is a new pest of longan. It is distributed in Fujian and Guangdong, and the main longan producing areas in Fujian Province are widely distributed. At present, it is only known that this insect harms longan, and adults eat the leaves of tender shoots. If insects are fixed on the back of leaves to suck, false gall will be formed, so the leaves are covered with small protrusions (called jatropha curcas leaves in southern Fujian), and the leaves become smaller and deformed, which affects the appearance of new shoots and the normal growth of leaves, and is serious in spring and summer.

Figure 2-55 psyllid in the corner of longan.

1. Egg 2. The first egg nymph 3. Mature nymph 4. adult

Morphological characteristics of (1) adults: body length (reaching wing end) is 2.5 ~ 2.6 mm, stout, back is black, abdomen is yellow, head is short and wide, buccal cone is developed, conical, and extends horizontally to the front. The compound eye is grayish brown, and the single eye is yellowish brown. The two nodes at the bottom of the antenna are brown, the two nodes at the end are black, and the rest are yellow, but the ends of the third to seventh nodes are yellow. The ends of the bristles are brown. The foot is yellow, but the tibia and tarsal joint of the forefoot, the tarsal joint of the middle hind foot and the melon are all black. The wings are transparent, and the front wings have obvious slightly "K"-shaped dark brown stripes. The abdomen is thick and tapered. Egg: long oval, tapering at the front end, extending into filaments, round at the back end and short stalk. The first egg is milky white and brown before hatching. Nymphs: * * * * 4 years old, pale yellow, surrounded by wax filaments, bright red compound eyes. The wing buds of the 3-year-old nymph are exposed, and the front and rear wing buds of the 4-year-old nymph overlap with brown stripes on the back.

(2) Living habits: Lycopodium longicorniculatum has about 3-5 generations a year in Fuzhou, with obvious overlapping generations, and some of them have diapause populations. The 2nd instar nymph does not develop in August and overwinters at the end of the year, and this type of life history accounts for the majority of the population. If the nymph is fixed on the new leaf, it will be harmful for life in gall. The 2nd instar nymph is deeply immersed in gall, and the adults feed on the tender buds, and lay eggs on the tender buds, leaves or twigs, mostly scattered on the back of leaves, mostly on both sides of veins. The adult peak period of psylla longan coincides with the shoot-shooting period.

Heavy rain has scouring effect on adults of psylla longan. Differences in nutritional status may affect the development of nymphs. Even the same leaf, due to different feeding points, the individual development speed is also very different.

There are three known predatory natural enemies, one of which preys on nymphs of psyllids; An ant preys on adult psyllids. In addition, there is a wasp parasitic on nymphs.

(3) Control methods Whenever the young buds germinate and psyllid occurs, spraying drugs can be used to protect the buds, and 40% dimethoate 1000 ~ 2000 times solution can be used; 50% DDVP emulsion 1000 times solution; 25% phoxim emulsion 400 times, or spray with pyrethroid diluent 2000 times.

4.Lawanalmita melichar (see figure 2-56) The white moth wax cicada (commonly known as "white chicken") belongs to Homoptera, the moth wax cicada family. Distributed in Fujian, Guangdong, Guangxi and Vietnam. It mainly harms citrus, longan, litchi and mango, and also harms many other fruit trees and economic plants. The harm of Fujian longan is quite serious. Adults and nymphs suck juice intensively on branches, twigs, flower spikes, fruit stalks and fruits, which makes the tree weak, the branches dry up, the fruit drops or fruits become smaller and the quality becomes worse, and its excrement can cause soot disease.

Figure 2-56 White moth wax cicada

1 .adult 2. Egg 3. naiad

Morphological characteristics of (1) adults: about 19 ~ 20mm long, yellowish white or turquoise, with white wax powder on the body. The head is conical, the compound eye is grayish brown, the antenna base is thick, other segments are bristle-like, and the front chest backboard is small and protrudes forward; The middle chest back plate is developed with three ridges on it. The front wing is pink-green or yellowish-white, the outer edge is straight, the apex angle is sharp and prominent, the middle parts of radial vein and buttock vein are brown, there is a white spot at the apex of wing chamber near the middle part of buttock vein, and there are several white spots at the outer edge of radial vein and the inner edge of buttock vein. The hind wings are jasper or yellow-white, translucent. Eggs: long oval, yellow and white. Nymphs: about 9 mm long, white, covered with cotton-wool wax, with bundles of thick wax filaments at the end of abdomen and truncated wing buds.

(2) Living habits: Nanning, Guangxi and Minnan have two generations a year, and overwinter among dense branches and leaves as adults. In February and March, the weather turned warmer, and the overwintering adults in Nanning began to move, mate and lay eggs. Late March to mid-April is the peak period of the first generation of eggs, and April to May is the peak period of nymphs. The second generation nymphs lay eggs from mid-July to mid-August, and the nymphs flourish from August to September. The first generation of nymphs occurred in March-April, and the adults occurred in May-June. The second generation nymph in July and August. Adult occurred in September, 65438+ 10. Adults lay eggs in buds and petioles, forming rectangular egg blocks, each of which has a dozen to twenty or thirty eggs. At the beginning, nymphs are clustered, but with the increase of age, they are slightly dispersed, often in groups of three or five. If worms and adults are good at jumping, adults can fly.

(3) Prevention and control methods ① Combine flower thinning and fruit thinning with pruning, and cut off dense branches and insect branches. ② Spraying with 80% dichlorvos emulsion, 90% crystal trichlorfon, 40% dimethoate emulsion, 50% cartap emulsion, or 50% phosphoramide emulsion 1000 times has better effect on nymphs. 1000 times dichlorvos or trichlorfon solution plus 0. 15% ~ 0.2% soda ash or washing powder is also effective for adults.

Fig. 2-57 Litchi Plutella xylostella.

1 .adult 2. Larva 3. pupa

5. The peach fruit borer (see Figure 2-57) belongs to Lepidoptera, which mainly harms litchi and longan. Morphological characteristics.

Bursaphelenchus xylophilus occurs in Fujian every year 1 generation. It overwinters as a larva in the trunk. If it is sunny and warm during the overwintering, it will still feed. Overwintering larvae pupate from mid-March to late April. From mid-April to late May, it emerged as an adult. Moths rarely look for sunlight. Laying eggs from late April to early June. Larvae appeared from mid-May to mid-June.

Most adults emerge in the daytime, rest on the trunk near the wormhole after emergence, mate and lay eggs that night, and the life span of adults is 2 ~ 9 days. Eggs are mostly laid on the bark of branches with a diameter greater than 12.5 cm. The egg period is 12 ~ 19 days, with an average of about 16 days. The larval duration is 286 ~ 343 days, with an average of 365438 06 days. The pupal stage is 27 ~ 48 days.

After the newly hatched larvae spread, they feed on branches, wounds and broken cork. Spinning weaves insect dung, branches and dander into tunnels and covers the insects; Then gradually nibble at the branches below the tunnel, forming a tunnel, which is the place where larvae live and pupate. Larvae lurk in the tunnel during the day and eat bark along the silk at night. With the growth of worms, the forms of tunnels are different, and inclined tunnels are more common. This kind of tunnel is inclined upward, and the mouth of the tunnel forms an angle of about 45 with the branches. When it reaches 1 ~ 2 cm, it turns parallel to the trunk. When larvae feed, they first feed on both sides of the tunnel, but some of them are far away from the tunnel. Tunnels are generally 20 ~ 30 cm long and the longest is 68 cm. The bark in the tunnel was not killed. It can be seen that the effect of tunnel on larvae is to escape from the enemy easily. The mature larvae spin silk to close the tunnel mouth, and then pupate in the tunnel. Pupa moves up and down in the tunnel, and the first half of pupa shell is exposed outside the tunnel after eclosion.

Prevention and control methods:

(1) Mud mixed with dichlorvos, methamidophos or other organophosphorus pesticides 10 times to block the tunnel mouth; Or cotton is dipped in the above chemicals and stuffed into the tunnel, and the mouth of the tunnel is closed with soil to kill the larvae.

(2) In June and July, spraying the above chemicals 800 ~ 1000 times on the branches near the silk hole can contact and kill the larvae.

(3) After August and September, the tunnel was blocked with bamboo and wooden sticks to suffocate the larvae. If this method is carried out in the 3 ~ 4 pupa stage, the effect is better, and steel wire can also be used.

6. Litchii (kicfer) belongs to arachnida, Acari and Carniidae. Commonly known as spider, litchi and longan are distributed in China. Adult mites and nymph mites eat leaves, flower spikes and young juices of litchi and longan, with buds and young leaves suffering the most. The injured parts are mostly on the back of leaves, producing colorless, transparent and sparse villi, which gradually turn into milky white. With the development of the scabies mite, the villi proliferate brown and look like "felt", and the injured leaves curl up like "dog ears". In severe cases, although the leaves of injured plants remain light green, the growth potential of plants is very weak. The damaged branches are dry, and the damaged ears are easy to drop flowers, which affects the fruiting and leads to the reduction of production.

The morphological characteristics of (1) are that the mite body is extremely small, generally invisible to the naked eye, and its body length is about 0.2mm ... It is light yellow at first, and then gradually turns orange. There are 1 pairs of pincers and whiskers at the head end, 6.6 cm feet at the head and chest, a conical abdomen and 1 pairs of hairy pseudofeet at the end. There are dense rings in the abdomen. Oval, light yellow, translucent and smooth. If the mite looks like an adult, slightly smaller, its body color changes from gray translucent to light yellow, and the ring pattern of the abdomen is not obvious.

(2) Living habits In Guangzhou, Lychee gall mite can occur 16 generations a year, with overlapping generations. When the average daily temperature in June is 28.7℃, it takes about 15 days to complete a generation, and it takes about 55 days when the average daily temperature in June is 1 15.48℃. Adult mites overwinter in the late autumn shoots or winter shoots in the crown, without real dormancy, and can still be seen above 10.5℃.

When the new shoots of litchi just germinate and the small compound leaves unfold, it is the main damage period, and the small compound leaves after unfolding are rarely damaged.

There are obvious differences among litchi varieties. Black leaves and Huai branches were seriously damaged, and cinnamon and glutinous rice paste were in the middle. Whether March Red is in hilly areas or water towns, the damage to adult trees or seedlings is extremely light.

The branches and leaves in the middle, lower and inner rooms of the crown are more damaged, while the upper layer with ventilation and light transmission is less damaged. This is consistent with the habit of sarcoptes scabies, which likes shade and fears light. However, there is little difference in the damage in the east, south, west and north of the crown.

In the ecosystem of litchi orchard, food is the key factor for the growth and decline of mite population, and the population of litchi gall mite develops at each twig stage. Among them, the peak period of gall mites on spring shoots is more common, while summer shoots and autumn shoots are often restricted by weather. Meteorology not only affects gall mites, but also affects their natural enemies.

(3) Control methods ① Agricultural control. Combined with postharvest pruning of litchi, the harmful branches, over-shaded branches, weak branches and diseased branches of gall mites are cut off, so that the crown is properly ventilated and light-permeable, which can significantly reduce the insect source and is not conducive to the occurrence of gall mites. Controlling winter shoots is also an effective measure to reduce insect sources. Especially important for young trees. ② Chemical control. When the population density is high, spray 800 ~ 1000 times of 20% dicofol emulsifiable concentrate mixed with 300 times of colloidal sulfur before topping or spreading young leaves. However, sulfur should not be used in high temperature and drought.

7. Lychee leaf gall midge. ) belongs to Diptera and gall midge. Since 1980s, the damage of leaf gall midge has been discovered in Guangdong, Guangxi, Hainan and other places, and the population has expanded rapidly, and the damage has become increasingly serious. Litchi leaf gall midge larvae invaded the tender leaves of Litchi, and water stains appeared. With the growth of larvae, waterlogging spots gradually protrude to both sides of leaves, forming small nodular galls. In severe cases, there are more than 100 scabies on a compound leaf, which can cause the leaf to twist and deform. After the larvae mature and remove the gall, the remaining gall gradually dries up with the aging of the leaves, and finally shows perforation.

Morphological characteristics (1) Adult: mosquito-like, slender, with smaller head than chest and slender feet. The female worm is 1.5 ~ 2. 1mm long, with slender and spherical antennae, annular bristles at each node, gray-black translucent front wings and dark red abdomen. The female insect is 1 ~ 1.8 mm long, with dumbbell-shaped antennae and annular filaments in addition to annular bristles. Feet and wings have the same characteristics as females. Oval, colorless and transparent. The larvae are transparent and colorless, orange-red when mature, 2.0 ~ 2.8 mm in length, and there are tan "ya" shaped bone fragments on the chest and abdomen. Pupa naked pupa, early orange-red, gradually dark red, before eclosion, wings, compound eyes and tentacles are all black.

(2) Life habit: Lychee leaf gall midge can produce 7 generations a year in Guangzhou and its vicinity, and the last generation 1 overwinters in leaf gall as larvae in June165438+1October. From late February to March of the following year, the overwintering larvae gradually matured, gradually emerged from the galls and entered the soil for pupation. In early April, overwintering adults often have two emergence peaks. In the following generations, due to the overlapping of generations, every insect in the field is in a state.