The yasukite, also known as the yasknisser, the yasukophora, and the pointed-headed mesomorphs, belong to the family Dipteridae. A common pest symptom is that female adults and nymphs are immobilized on citrus leaves, branches and fruits to suck sap, resulting in curly yellowing and yellowing of the leaves, the branches withering, the fruit not fully ripe, and the fruit taste sour, causing very serious trouble to orange farmers.
To this end, it is necessary to systematically understand and understand the citrus yascalyptus, and adopt targeted control methods, which will achieve better results.
Citrus yascas is harmful to citrus fruits
It is distributed in Shanxi, Shaanxi, Shandong and various citrus producing areas. It is found in Japan, India, Oceania and North America.
It is a large pest known to fruit farmers, and its harm to citrus is the most serious, with a wide area of disaster, high frequency of outbreaks, many pesticide varieties and dosages, and great economic losses. Host plants are citrus, orange, grapefruit, persimmon, peach, pear, apricot, grape, tea.
The yasknith pests citrus leaves, branches and fruits and absorbs nutrient solution. Light leaves fade green and yellow, the peel is solid with insect shells, the damage point is green and not colored, affecting the value of the commodity, and the tree is seriously weakened when it is heavy, and it cannot be pulled and the fruit cannot even die.
The arrow-tip is a tree that is seriously damaged, and citrus anthrax often occurs in combination, prompting the early wilting of orange plants.
Citrus yaspers cause death to citrus plants
1. Female adult of the sagittarius silkworm Female adult shell of the female sagittarius is 2.4 to 3.8mm long, about 1mm wide, brown, and the shell edge has white edges. The anterior tip is wide and the posterior end is wide, and there is a longitudinal ridge in the dorsal area, which is shaped like a arrow. The first and second molt shells are located at the anterior end, orange-yellow, female adults orange-yellow, 1 to 2 mm long and 0.6 to 1 mm wide, with a long thorax, a short abdomen, and anterior and mid-thorax distribution is not obvious.
Male adult shell is narrow and elongated, composed of white waxy powder, the back of the shell has 3 longitudinal ridges, parallel on both sides, the molting shell is located at the front end, 1.3 to 1.6 mm long; clustered into pieces, in a powder pile on the leaves, the male adult is about 0.5 mm long, the wings are colorless and transparent, the wings are about 1.6 mm, and the hind wings are 1 balance stick.
Citrus yaspers cause dry leaves and dead branches
2. Male adults of sagittarius flies Male adult antennae 11 segments, black eyes, abdominal end with needle-like tailcross, the length of which is about half of the total length of the chest and abdomen; the oval oval, the size is 0.2mm x 0.1mm, orange, smooth.
The newly hatched larvae are orange-yellow, flattened, 0.25 mm long and 0.15 mm wide, with pale brown antennae, 7 segments, 1 pair of tail hairs at the end of the abdomen, and like to swim and crawl.
2nd instar nymphs are sedentary and sucked, pale yellow, 1 mm long and 0.6 mm wide, dark brown eyes, obvious antennae, thorax and abdomen segments, clear longitudinal ridges, disappearing tail whiskers, and male and female are recognizable.
Males have 1 more segment of abdomen than females, and their heads have several slender wax filaments, and their body color is slightly darker.
The pre-pupal is molted by a 2nd male nymph, 0.7 mm long and 0.3 mm wide, oblong-ovate, orange-yellow. The eyes are dark brown, the mouth needle disappears, and the tentacles and feet are attached to the body. The pupa is orange-yellow, 0.8 mm long and 0.3 mm wide, with obvious antennae segmentation, 3 pairs of feet gradually extended, and the tail patch is prominent.
Citrus yasperm is harmful to branches and leaves
Guizhou, Sichuan, Jiangxi, Hubei and Hunan provinces orange areas occur 2 to 3 generations a year, and some areas in Guangdong, Guangxi, Fujian, Yunnan and Chongqing occur 3 to 4 generations per year.
The generations overlap severely, mostly overwintering with fertilized females, and the eggs are laid under the maternal mesembran, and the nymphs can hatch within a few hours, and the hatching rate is as high as more than 80%.
In the 3rd generation area, the overwintering (third generation) females lay the most eggs, laying 150 to 160 grains per head; the first generation was second, 120 to 150 grains; the second generation was the least, generally 20 to 40 grains. In terms of hatching and developmental quality, the number of nymphs is larger, the number of adults is smaller, and the number of males is more and the number of females is small.
Citrus yasuts are leaf-like
Since the amount of eggs laid by female insects varies greatly from generation to generation, the peak and degree of harm in the field are consistent. In Duyun, Guizhou, orangery yascalyptus occurs in mid-to-late April to early May as overwintering adult spawning.
The peak of the first generation of larvae in early to mid-May, the peak of the second generation of insect pests from mid-July to early August, the peak of the third generation from late September to late October, and the female adult insects enter the winter in late November.
The egg stage is extremely short, averaging about 1 h. The first nymph stages of each male beetle generation were 18-23d, 14-18d and 16-21d, with an average of 20.6d, 16.8d and 17.2d.
The 2nd instar nymph stage is about 10 d, the pre-pupal stage is 1-2 d, the pupal stage is 3-6 d, and the adult lifespan is 1-3 d, which is very phototropic, and can induce prediction of the occurrence period.
Citrus salient borers are harmful to the leaves
The salient silkworm reproduces both sexes and cannot reproduce parthenogenetically. Female adults begin to lay eggs after mating when the average daily temperature rises to 19 °C, and stop laying eggs when they drop below 17 C.
The eggs are laid at the posterior end of the mother under the mesohus, and the hatching rate of eggs is very high, up to 87% to 100%. The hatching nymphs are active, crawling around, looking for appropriate parts, and can spread to distant places with the wind or animals, and after 1 to 3 hours of activity, they will fix the sap.
The foot gradually becomes smaller, the body begins to secrete wax the next day, after 2 to 3 days the middle of the worm secretes gray thin wax, gradually expanding the back of the body, the 2nd instar female nymph forms a soft membranous shell, and longitudinal ridges and wrinkles appear before molting.
Male nymphs secrete white cotton-wool waxy substance after 2 years of age, gradually form a mesembranous shell, shed the second skin under the mese shell to become a pre-pupal, and then molt once into a pupal, and then feather into an adult worm.
Females are scattered and parasitic, and most of the males cluster on the back of the leaves. It begins mostly as a star dot in the lower and inner hidden parts of the canopy, and then gradually spreads to the upper and outer layers. Orange groves with hidden or large and unventilated tree canopy are often seriously harmful.
Female nymphs of 1st to 2nd instar and male nymphs and male adults of 1st instar are sensitive to agents, and male nymphs of 2nd instar are covered with a shell and are not easy to kill, and female adults are the most resistant.
Citrus yasuts harm the leaves
1. Agricultural control When pruning and shaping in winter, in order to harm the general orange tree, cut off the infested branches with insects, scatter them around the orchard, and do not destroy them.
Because the insect body no longer continues to harm the living tree on the pruned leaves, many natural predators that parasitize the female adults, such as the golden aphid wasp and the arrow-tip aphid wasp, are preserved, and fly to the first generation of nymphs to parasitize in the spring of the following year.
For dying trees that are affected by a mixture of this insect and anthrax, chemical pesticides kill all pests on the tree, and it is difficult to restore their prosperity. When the tree is dormant in winter, it must be re-cut, leaving more than ten backbone branches, applying plantar fertilizer, and when the spring shoots are extracted, they must be weak and strong according to the orientation and level, and protect them into a new canopy, which can become a productive tree in two years.
Citrus sativa
2, pharmaceutical control prevention and control strategy is to control the middle of the two ends (generation), due to the long spawning period of female insects in the overwintering generation, the amount of eggs is large, so in the garden where the harm is serious, the first generation of prevention and control is generally carried out twice. For orchards with a small amount of arrow-tip insects, it is not prevented, prevented concurrently, or only once a year.
It is advisable to choose a non-toxic high-fat film, a 95% oil emulsion or a variety with little toxicity to natural enemies. The effect of application in the dispersion and transfer period of nymphs is good, the insect body has no wax powder and shell, and the resistance to drugs is weak.
It can be used 240g/L spironium ethyl ester 4000 ~ 5000 times liquid, 10% pyrithione emulsion 1000 ~ 1500 times liquid, 25% thiazinone wettable powder 1000 times liquid or 30% nitrox thiophosphate emulsion 750 times liquid, 40.7% chlorpyrifos 800 ~ 1500 times liquid, 20% imidacloprid wettable powder 2000 times liquid. Mineral oil emulsion can also be used, with an oil content of 0.5% in summer and 3% to 5% in winter.
During the first generation of nymphs, spraying with 24% spirant ethyl ester suspension 4 000 times liquid - once can effectively control this pest. Spray canopy leaves on both sides and branches of fruit, small nymphs are applied at their peak.
3. Biological control, protection and utilization of natural enemies.