Wheat aphid, commonly known as pallet, is an important pest on wheat in China, the main species include wheat long pipe aphid, grain pipe aphid, wheat two aphid and wheat netless long pipe aphid. Wheat long pipe aphid occurs in wheat areas throughout the country is the main aphid in most wheat areas, wheat two aphids are mainly distributed in the winter wheat areas in northern China, especially in north China, northwest China and other places where serious occurrences occur in north China, northeast China, south China, east China, southwest Wheat areas in rainy and humid wheat areas are often dominant in wheat without nets long pipe aphids are mainly distributed in Beijing, Hebei, Henan, Ningxia, Yunnan and Tibet. Wheat aphids can not only directly suck wheat juice but also spread viral diseases for many years, resulting in a reduction in wheat production by more than 10% in large-scale years.
Wheat aphid pest symptoms:
At the wheat seedling stage, wheat aphids are mostly concentrated on the back of wheat leaves, leaf sheaths and heart leaves; after wheat jointing and ear extraction, they are mostly concentrated in stems, leaves and ears, and excrete honeydew, affecting plant respiration and photosynthesis. The victims are pale yellow spots, and in severe cases, the leaves turn yellow, or even the whole plant dies. The panicle stage is harmful, resulting in insufficient filling of wheat, dry grains, and a decrease in the weight of 1,000 grains, resulting in a decrease in wheat yield.
Wheat aphid occurrence conditions:
The occurrence and growth of wheat aphids are affected by meteorological factors such as temperature, humidity, wind, and south, and are also closely related to factors such as host plants, cultivation management measures, and natural enemies.
1. Meteorological factors wheat two aphid is the most resistant to low temperature and likes to dry. The max binary begins to move at about 5 ° C, and the reproductive temperature is 8.2-20 ° C, and the optimal temperature is 13-18 ° C. The suitable relative humidity is 35%-67%, mostly in areas with annual precipitation below 500 mm. Wheat tubes have little activity below 8 ° C, the suitable temperature is 16-25 ° C, the optimal temperature is 16.5-20 ° C, and the growth stagnation above 28 ° C. The suitable relative humidity range is 40%-80%, and the most suitable is 61%-72%, mostly in places with sufficient rainfall and watering. Grass valley tube aphid is the most resistant to high temperature and high humidity, generally at an average daily temperature of 8 ° C to start activities, 18-24 ° C is the most advantageous, 30 ° C can also quickly breed as a pest. The most suitable relative humidity van solid is 68%-80%.
2. The host plant wheat crop is the main host plant of wheat aphid, but the degree of preference of aphids to different hosts varies in order of wheat, barley, oats and rye. Wheat varieties have different degrees of occurrence. The degree of occurrence of wheat aphids varies greatly depending on the growth of wheat. The aphid volume of the second type of wheat field with the largest growth density of wheat aphids is 50% of that of the wheat field: the aphid volume of the three types of wheat fields with poor growth is only about 15% of the first type of wheat field.
3. The change of the number of wheat aphid population under cultivation conditions is closely related to wheat sowing period, tillage mode, fertilizer and other conditions. Early-sown wheat fields have more aphids in autumn than late-sown wheat fields, and in spring, late-sown wheat fields have more aphids than early-sown wheat fields: wheat fields intercropped with vegetables, cotton, trees, and other flowering plants have a lighter occurrence of wheat. In the spring, there is a lot of aphids in the wheat field with sufficient fertilizer water.
4. There are many kinds of natural enemies of natural enemies, including more than 50 common species, which are divided into two categories: predatory natural enemies and parasitic natural enemies. Predatory predators with strong control over wheat aphids are the seven-star ladybird, heterochromatic bottle worm, and turtle pattern ladybird of the family Aphididae: the great gray aphid fly of the family Sissycephaeae, the oblique-spotted drum-frontal aphid fly and the Chinese grasshopper, the large grasshopper and the lily grasshopper of the black-banded aphid fly family, the small black spider and the trident flower spider; and the smoky aphid cocoon bee and oatme cocoon bees of the parasitic aphid cocoon family.
Wheat aphid control methods:
1. Agricultural prevention and control and strengthening cultivation management is an important way to control the occurrence of wheat aphids. Removal of field weeds and self-growing wheat seedlings can reduce the suitable habitat and summer host of wheat aphids. The implementation of winter wheat, garlic and leguminous crops intercropping has a good effect on the protection and utilization of wheat aphid natural enemy resources to control aphid infestation. Appropriate late sowing of winter wheat and timely early sowing of spring wheat are conducive to reducing aphid infestation
2. The use of insect-resistant varieties to control the occurrence of wheat is a safe, economical and effective measure. At present, some varieties of materials with medium or strong resistance have been screened.
3. Biological control fully protects and utilizes natural enemy insects, such as ladybirds, aphid flies, grass catfish, aphid cocoon bees, etc., and if necessary, artificial breeding can release or assist the migration of natural enemies, so that they can effectively control aphids. When the ratio of natural enemies to Max is greater than 1:120, the natural enemies have a better effect on controlling wheat aphids, and there is no need for chemical control; when the beneficial pest ratio is above 1:150, if the natural enemies show a significant upward trend, they can also be prevented without medication. When the prevention and control of wind and rain weather at the right time, chemical control can be postponed or not.
4. Physical control in the early stage of wheat aphids evenly insert 15-30 yellow plates per acre the height is 20-30 cm higher than that of wheat, when the area of armyworms on the yellow plate reaches more than 60% of the surface area of the plate, it is appropriate to change the suspension direction to the plate facing the east-west direction.
5. Ecological regulation of biodiversity is the basis for maintaining ecological balance in nature and inhibiting the outbreak of plant insect pests. Multiline varieties and cultivar mixes increase crop biodiversity Natural enemy species and number increases In addition, varietal mixes make wheat varieties odors mask each other Aphids are not easy to find favorite host plants can inhibit the growth of their numbers. For example, wheat and rapeseed, garlic beans, mung bean intercropping or adjacent crops have a good aphid control effect. Wheat pest induction of wheat release of volatiles Aphid alarm hormones and plant hormones such as methyl phenylate and salicylate Ace have a repellent effect on max but have a strong attraction effect on the parasitic and predatory predators of wheat aphid can be artificially synthesized into a sustained release device in the wheat field to release interference wheat host positioning, inhibit its feeding enhancement of natural enemies Attraction effect can effectively reduce the pest of wheat and will not bring about the side effects of traditional chemical pesticides
6. Chemical control When the number of wheat aphids occurs in large quantities, and measures such as agricultural control and biological control cannot control them, chemical control is an effective measure to control aphid infestation. During the grain filling period, the amount of 100 aphids mainly based on wheat long pipes reached more than 500, and the amount of 100 aphids mainly based on grain pipe aphids was more than 4000 for chemical control indicators. When the amount of 100 plants of aphids reaches the control index, the benefit-harm ratio is less than 1:120, and there is no heavy wind and rain in recent days, the drug control should be carried out in time.
Commonly used agents are: 3% acetamidine emulsion each mu 20–30 ml, sprayed with water during the initial occurrence of aphids in the wheat ear stage, 50% anti-aphid wettable powder 10–15 grams per mu, can control wheat seedling aphids or spray water at the peak of spike aphids. Plant-derived insecticides can also be selected, such as 0.2% matrine water agent 150 grams per mu, 30% synergistic nicotine emulsion 20 grams per mu and 10% saponin nicotine 1000 times liquid and antibiotic 1.8% avermectin emulsion 2000 times liquid and other spray control wheat lizards, the prevention effect is more than 90%.
It is necessary to pay attention to improving the application technology, selecting selective agents that are safe for natural enemies, reducing the number and quantity of drugs, and protecting natural enemies from harm.