Greenhouse whitefly
The greenhouse whitefly (Trialeurodes vaporariorum Westwood) is commonly known as the white moth and belongs to the order Homoptera, Pteromidae. It was originally a kind of pest in greenhouses in northern China. Since the 1970s, with the rapid development of plastic shelters and other protected areas, its distribution area has gradually expanded. In addition to killing melons and watermelons in greenhouses and greenhouses, the host plants have reached 70 families and 270 species of plants, such as cucumbers and tomatoes, and many other crops.
Hazardous characteristics: Adults and nymphs take plant sap, and the victim leaves are chlorotic, yellow, wilt, and even dead. The secretion of a lot of honey liquid, serious pollution of leaves and fruit, often cause the occurrence of coal pollution disease, can also be transmitted through the virus infection Bo Bo?
Morphological characteristics Adult body length 1 to 1.5 mm, pale yellow. Wings are covered with white wax powder, and when they are resting, their wings form body ridges like moths. The egg is about 0.2 mm long and has a long oval side view. It is inserted into the plant tissue from the stomata in the back of the leaf. The 3rd instar larvae were 0.51 mm in length, pale green or yellow-green, and their feet and tentacles were degraded. They clung to the leaves and clung to life. The 4th instar nymph is also called pseudogermanium and has a body length of 0.7-0.8 mm. It is oval in shape. It is initially flat and gradually thickened into a cake-like shape (side view). The center is slightly taller, yellowish-brown, and the back of the body has wax of varying lengths. Body side thorns.
Occurrence characteristics? There can be more than 10 generations in one year in the northern greenhouse, and it cannot survive outdoors in winter. It is wintering in the greenhouse in each insect state and continues to be harmed. One to three days after emergence of adult mate can lay eggs, with an average of 143 per female. Parthenogenetic reproduction can also be performed, and its offspring is male. Adults tend to be tender, always chasing the top leaves spawning as the plants grow. The egg is inserted into the leaf tissue from the stomata with its egg stalk, and the host maintains the water balance and is not easy to fall off. The nymphs hatch in the back of the leaves for a short distance within 3 days after hatching. When the mouthparts are inserted into the leaf tissue, they lose their ability to crawl and start to live in a solid state. The breeding temperature of whitefly is 18 to 21°C, and it is completed in the greenhouse for about 1 month.
Prevention and control methods: Since whitefly adults, larvae, and eggs all occur at the same time on one plant. Waxy body surface, strong resistance, and some pesticides on the eggs and cockroaches is low. Most of the adults live on the back of the leaves, and they are easy to escape the poison of pesticides. In addition, the adults are active when the light intensity is strong. Under the conditions of sufficient sunlight, the body is not easy to get the medicines, the insects quickly escape, and the density of the insects can be recovered quickly after chemical control. From the point of safe and practical application of pesticides, it must also meet pollution-free standards, which all bring great difficulties to the prevention and control of greenhouse whitefly, and must therefore be integrated and controlled before they can be effective.
1. The importance of agricultural ecological control
(1) Incubate insect-free seedlings, turn good seedlings off, strictly implement nursery management, prevent whiteflies from occurring during this period, and lay foundations for thorough prevention and control. Production greenhouses must completely remove the defects, leaves, and residues of the former crops before planting. The weeds are wiped out and transported out of the plant for outdoor treatment. If necessary, low-temperature extermination methods are used. The greenhouses are all open for 3-5 days in cold winter temperatures from December to early January. The greenhouses are then closed, and high-concentration non-polluted pesticides are applied at the same time. Dichlorvos can be used for fumigation (sprinkling of dichlorvos on sawn timber or wheat straw and straw, plus burning red coal balls to smoke), equivalent to 666.7 square meters with dichlorvos 0.25-0.5kg, this method can only be effective for adults, so it needs to With 25% buprofezin (Quinone, Youdele, Aleede) WP 1500-2000 times spray, have a certain inhibitory effect on adults, larvae, eggs, do not kill natural enemies, because this drug is Worm skin is dead, so it takes 3 to 7 days after application. However, the residual period of insecticide can last for more than 20 days. Therefore, it is better to eliminate residual insect pests in the greenhouse and achieve the goal of no insects in the greenhouse.
(2) Set up a curtain for avoiding insects, cover 200 mesh white cold yarn (insect protection net) at the entrance and ventilation of the greenhouse (shed) to prevent whiteflies from flying into life.
(3) Try to avoid mixed planting, adjust the mouthwash, eat greenhouse eggplant, tomato, cucumber, beans, strawberries, a bunch of red, sunflower and other hairy plants, so the cucumber, tomato, beans, squat Arrangements for sweet peppers, canola, spinach, celery, leeks, etc. should be arranged to reduce the risk of greenhouse whitefly.
(4) The old leaf disease was burned and destroyed because the old nymphs were mostly distributed on the lower leaves. When the eggplant vegetables were pruned, some old yellow leaves were taken out and buried deep outside or burned out to reduce the whitefly population.
2 physical control technology? Physical method prevention and control is to avoid pesticide pollution, one of the effective low-cost scientific control methods.
(1) Insect-proof nets are used in protective cultivation. Insect-proof nets are high-quality polyethylene raw materials that are added with anti-aging, anti-ultraviolet and other chemical additives. They are made by drawing and weaving. They are in the form of window screening and have high tensile strength and resistance. Heat, water resistance, corrosion resistance, aging resistance, non-toxic and tasteless features. Insect nets are artificial barriers constructed by insect nets, with white nets of 1.25 to 1.875 mm in diameter, and the insects are rejected from the net, thus receiving pest control effects. The effect of insect repellent and anti-hazards is very obvious, and the service life of the network can reach 5 years
(2) The use of greenhouse whitefly has obvious tropism towards yellow and green. The room temperature is high before and after noon, and the light intensity is high. Yellow trapping can be used to obtain better control effects. Every 1/2 square meter of 615cm plastic rod (coated with glue shellac) is hunted and killed at a height of 70cm above the ground. It is a good pollution-free control technique, but the correct yellow color is noticed. The plastic strip is tested on the basis of 315cm and 615cm. It is confirmed that the effect of increasing the width of the ribs within a certain range is higher. However, although the area of ​​the 915 cm yellow plastic strip is large, the trapping amount is reduced. This is why yellow trapping is not as good as the yellow strip trapping. The second is to use the glue to keep viscosity for a long time, if the glue can not buy when using 10th oil instead of 10th oil should be added a little butter and mix, application or 27 parts of rosin ester and 12 parts of castor oil , After heating and melting, add 1-3 parts of stabilizer, stir and finally add 3 parts of honey to stir well, use after cooling, recoat once every 7-10 days.
3, biological control? Because the greenhouse whitefly breeding speed, overlapping generations, the existence of each species and body wax powder, such as the continuous use of the same pesticide, pesticide efficacy is difficult to play, while the drug resistance is also rapidly increased, so blindly The use of chemical pesticides can often not be controlled. In nature, many insects can prey on greenhouse whitefly, such as grasshoppers, multiple parasitic bees, ladybugs, etc. We have put Chinese grasshoppers, natural predators and red bees in the greenhouse. The successful prevention of mold has proved to be a promising technical measure.
(1) Chryxsopa sinica tzeder can be periodically released by artificial feeding. The Chinese grasshoppers were reared in the Beijing-Tianjin area in April and released in greenhouses in June to control whiteflies. The grasshoppers larvae developed normally after eating whitefly, and they survived even at 37-38 degrees Celsius in the greenhouse. Grasshoppers can prey on 172.2 heads of third-instar nymphs and use grasshopper nymphs to feed grasshoppers. Methods Eggs are wrapped around plants on the 3rd, 8th, and 15th of June and stapled on the back of the leaves. Each of the five strains established a releasing point of 1800 square meters to release 90,000 eggs, which confirmed that it can control the damage of whitefly in the greenhouse. However, when the proportion of grasshoppers and whitefly is less than 1100, it often cannot be controlled.
(2) The application of Encarsia formosa, which mainly uses the spawning larvae to lay eggs in the whiteflies nymphs. The larvae parasitize the nymphs and the parasitized whiteflies turn black after 9-10 days, followed by nymphs. death. The test whitefly has four to ten whiteflies on each leaf of the upper tomato and 50 to 60 heads of cucumber, three times every two weeks. The release of 15 larvae and bees into the bee can reduce the size of the whitefly. Too much growth, the use of larvae to kill the whitefly benefits, is its strong anti-pesticide, such as spraying the bee for the prevention and control of other pests and diseases such as jaundice spraying dicofol, deltamethrin, trichlorfon, music For fruits or diazinon pesticides, the death rate of parasitic black locust was only 1.82%, and the fungicides such as zein zinc, thiophanate, chlorothalonil, ethyphosphine aluminum, and thimemus were sprayed, and the death rate of bees was only 1.42%. Therefore, it is not affected, and the reed bees can still establish populations in the greenhouse, and can effectively control whitefly damage.
(3) Bacteroides hirsutum (Verticillum lecanii) can parasitize whiteflies and cause epidemic pathogens. The colonies can grow at 7-23 degrees Celsius to produce conidia and colony growth is the most suitable temperature. For 23-28 degrees Celsius, the conidia temperature is 23-25 ​​degrees Celsius, which is suitable for the low winter temperature and large temperature difference between day and night in North China, but the spores need more than 80% relative humidity to grow well and the humidity is 74%. When the spore parasitism was only 28.08%, due to high humidity conducive to the occurrence of many fungal diseases, spray fungicide can also kill the red fungus mold, so in practice received certain restrictions.
4. Chemical prevention and control technology Chemical pesticides are one of the integrated prevention and control of planting suitable vegetable species, avoiding mixed planting, cultivating insect-free seedlings, preventing biological control and physical control from playing each other's advantages, and rationally applying low-toxic pollution-free chemical pesticides. .
At present, greenhouse whitefly pesticides are being controlled. With the progress of pesticide science, the following pesticides are sprayed when the greenhouse adults average 2.7 heads per plant:
25% buprofezin (buprofezin, omeprazole, Utara, Bufungin, Inabajing, Indole, Aleed) WP 1500-2000 times, because the medicine is to kill insects Synthetic insect growth regulators, so the effect can be effective after 3-4 days of application, the adult oviposition and larval hatching have a certain inhibitory effect on natural enemies and beneficial insects have no significant effect, drug residual period can be maintained for 20-30 days.
2.5% Uranus (bifenthrin, trifluthrin, instarac) EC 3000 times, low toxicity, safe to human and livestock crops, low dose, low environmental impact, can be used as a pest control for green foods The biggest advantage is that it can still exert a strong effect at low temperatures. The efficacy lasts 15-30 days, killing adults, larvae, and pupa. The effect on eggs is not obvious.
20% extinction cream (fenpropathrin) 2000 times, or 15% Prempt (15% exfoliant and 5% S-71639 sex hormone) 2000 times.
2.5% Kumquat Chrysanthemum (trifluthrin, PP-321) 3000 times EC, 2.5% extinguish butylate (Salmethrin, Fenvalerate, cypermethrin, chloranthone) EC 2000 Times of liquid, 10% permethrin (pyrolomethrin, diflubenzuron, permethrin) EC 3000 times, 21% eradicator (cyanoma EC) 4000 times, effective for adult nymphs Can not kill eggs or slander.
20% imidacloprid (Confodome, one-time net, big meritorious, osmotic net, fluocin, chlorfenapyr, iridoxamine, dexamethasone, bidan, morpholin, iron palm) SL2500-5000 times, spraying After 1-15 days, the control effect can reach 75.6-96.5%, which is obviously higher than that of 20% extinct EC and some pyrethroid pesticides 200 times, and the toxicity is also low. It is a good medicine for control of greenhouse whitefly, and there is also complex With 25% isopyrazole (Isopropylimidazole imidacloprid) 20% geminal (Imidacloprid mixed phoxim) 3000 times.
Abamectin (Zevocin, chlorimurin, pest extermination, insecticidal 7051 phytocyanin, abbachin, avermectin, avermectin, avirin, love Fu Ding? Love Elixir, Insect Nemesis, Insect Moth, Insect Mole Chik, Insect Pest, Exterminator, Nonghaha, Azirodin, Qitunmycin, Strong Stick, Aweifenjing, Special In addition, the dilution factor is slightly different due to various contents. This medicine interferes with the neurophysiological activities of insects, has a weak fumigation and contact toxicity, and has a stomach-poisoning effect, and has no systemic absorption effect. But there is a strong osmotic effect, do not kill eggs, low toxicity, long duration, in addition there is a compound of 40% green vegetable treasure (avermectin mixed dichlorvos), 35% gram moth (Phoxim mixed Abamectin) control.
Application Principle of Whitefly in Greenhouse
As the greenhouse whitefly has phototaxis and is protected by wax, spraying should not be carried out at noon on a sunny day. Otherwise, even if the most efficient pesticide is used, it is also a matter of “multiplying effortsâ€. It is necessary to use the characteristics of living habits of the whiteflies at night to master the night. After 9 o'clock in the morning or at 35 o'clock in the morning, the best effect can be fully exerted. In addition, due to the waxy protection of the adult's body surface, it has a certain tolerance to chemical pesticides. In addition, adults, larvae and eggs are simultaneously on one plant, and some pesticides are only It is effective for adults or other insects and is not effective for eggs. Therefore, it is necessary to spray once every 5-7 days to control the breeding of whiteflies, and the spray concentration is too frequent or frequent, and it is also easy to produce drug resistance or drugs. Harmful, so the application of chemical pesticides, must use a variety of pesticides alternately, but also with ecological, physical, biological technology, comprehensive treatment, in order to receive the highest results, such as the application of ultra-micro sprayer can also be more effective.
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