<h1 class = "pgc-h-arrow-right" > the control of bitter melon spotted flies</h1>
Spotted flies are harmful insects such as melons, legumes, nightshades and umbelliferous flowers, and South America is its origin and is distributed in regions other than Qinghai, Tibet and Heilongjiang. Spotted flies not only affect the normal growth process of plants, but also may spread toxins, posing a threat to human life and health. Therefore, it is necessary to strengthen the control of spotted diving flies. In view of this, on the basis of introducing the American spotted diving fly and its harmfulness, the article explores several practical prevention and control measures.
<h1 class= "pgc-h-arrow-right" >1 American spotted flycatcher </h1>
Adult American spotted flycatchers are small in size, with a yellow head and black orbit behind the eyes; The mid-thoracic dorsal plate is black and shiny, and the mid-thoracic side plate is dominated by yellow; The feet are yellow; The eggs are white and translucent; The larvae are maggot-like, translucent in the initial incubation stage, and gradually develop into a bright orange-yellow color; It is oval in shape, orange-yellow in color, and is about 1.3 to 2.3 mm long.
It can occur in 10 to 12 generations throughout the year, and it is explosive. It winters in the form of pupae in the topsoil of the lower part of the host plant. There are two peaks in the year, June to July and September to October. The American spotted fly has strong adaptability, a wide host range, strong reproductive ability, short succession, and adult insects have characteristics such as phototropism, green, yellow and honey.
<h1 class= "pgc-h-arrow-right" >2 Hazards of spotted flycatchers </h1>
Spotted flies can needle-prick and lay eggs inside bitter melon, which damages the structural integrity of bitter melon cells and forms circular puncture holes similar to the size of needle tips, causing more obvious harm. The "hole" is light green in the early stage, and then becomes white, which can be observed by the naked eye. The harm formed by larvae and adults may cause the entire seedling to die, causing a more obvious phenomenon of lack of seedlings and ridge breakage; Damage to the adult plant may promote the process of the bitter melon falling, resulting in the bitter melon being covered with maggots and inedible. Larvae and adults may also spread diseases through feeding, especially some viral diseases, resulting in different degrees of reduction in the ornamental value of flowers and the edible value of melons.
<h1 class = "pgc-h-arrow-right" >3 Control methods of bitter melon spotted fly </h1>
3.1 Agricultural control
Try to choose varieties that are strongly resistant to disease, and when conditions permit, appropriate rotation of non-parasitic plant crops to cut off the food source of spotted flies. Before planting vegetables in early spring and autumn, the weeds, stumps and leaves in the vegetable field are gathered together as much as possible and then burned, the purpose of which is to reduce the source of insects. Before planting, the vegetable field is deeply turned over, and the pupae that remain on the ground are buried alive. It is best to apply 3% Miller granules 1.5 to 2.0 kg per acre of vegetable land to kill pupae. During the peak period, flies can be exterminated in the form of medium-tillage loose soil. In addition, if there is a submersible channel found on the leaf of vegetables in the indoor environment, it should be removed in time, the weeds inside and outside the greenhouse should be eradicated, and then burned in a concentrated manner to reduce the source of insects.
3.2 Protection and utilization of predators
In the past, it has been reported that if the parasitization of American spotted fly larvae is found in the vegetable field, the parasitic natural enemies are mainly Li submerged fly ji wasps, anti-collar cocoon bees, submarine fly cocoon bees, etc., and released in time can significantly reduce the parasitic rate of spotted fly. Therefore, the protection and utilization of natural enemies should be strengthened, and it can play a better role in the prevention and control of american spotted flycatchers.
3.3 Physical Prevention and Control Law
(1) Yellow plate booby trap. Adult American spotted fly divers have strong yellowing, and this property can be used to trap adult insects by placing 20 cm × 20 cm yellow plate in greenhouses or vegetable fields.
(2) Fly-killing paper booby-trapping. This kind of control method is best used in the early to late adult period, and 15 booby-trap points can be placed per mu of land, and 1 piece of fly-trap paper is placed at each site to trap the adult insects, and it is replaced every 3 to 4 days.
(3) Booby trap. It is recommended to use in conjunction with the armyworm yellow plate. During the specific application, first insert a lure core into the center of the stickworm yellow board, and then tear off the release paper, and the fingers should avoid touching the glue; Hang 30 sets evenly per acre of farmland; It is started to hang from the early stage of spotted flying, and usually can achieve better control results; The application environment is the main factor affecting the duration of the effectiveness of the core, usually > 30 days. If a decrease in enticing capacity is observed, it must be replaced immediately; If the number of armyworm plate armyworms is found to be too large, which has an adverse effect on gloss and annuality, it should also be replaced in time.
(4) High temperature and stuffiness. Now there have been studies that have found that in the environment of 48 ° C, the mortality rate of 1h pupa is as high as 100%, and the watering is 1 time before the treatment of the shed, and after the next day the greenhouse is closed and heated to 48 ° C, the air outlet is slowly opened and normal temperature management can be restored.
(5) Low temperature freezing shed. If in a colder area, you can use outdoor cold conditions to freeze the shed before the vegetables are planted, and usually the shed can be opened and frozen for 3 to 7 days to kill various insect pests.
3.4 Chemical control
American spotted diving fly belongs to China's quarantine pests, the main targets of harm are bitter melon, eggplant, tomato, potato and so on. Larval leaf diving may form a more obvious damage to the host plant, resulting in the destruction of chlorophyll and mesophyll cells, the development of the plant is significantly delayed and withered, resulting in a decrease in yield, and in severe cases, it will cause the plant to lose its commercial value, and even lead to the failure of some vegetables and fruits. Each region should implement targeted response measures based on specific local conditions, and recommend the alternating use of different single agents in the use of chemical agents to prevent pests from forming strong resistance. Commercial formulations of Bacillus thuringiensis have been shown to be more effective in mitigating the severity of damage in the American spotted fly and have no lethal effect on natural predators.
The focus of chemical drug control is the "quasi" timing of application, most of the larvae are most active on the leaf surface between dry dew in the morning and 11 a.m., and the old mature larvae are good at exposing the upper part of the leaf surface by the insects in the early morning, which is the best time to administer the drug to control the larvae. Spray once every 12 days, spray 2 to 3 times continuously, usually can achieve better control results.
3.5 Control by yellow rhododendron extract
In the past, it has been reported that the extract of Rhododendron yellow can have a more obvious effect on the pupa feathering process and can reduce the feathering rate of pupae. In addition, the extract can play a more obvious role in the feeding process of adult insects, and can achieve excellent control effects in farmland, the medicinal effect is relatively stable, the duration is longer, and there is a good application prospect in agricultural production.
3.6 Insect net
Its role is to prevent spotted flies from entering the shed for pests, growth and reproduction. It is recommended to cover the whole growth period, and before covering, the removal of the residue in the shed should be done, and the soil around the insect net should be compacted to prevent spotted flies from sneaking into the shed to lay eggs.
<h1 class="pgc-h-arrow-right" >4 epilogue </h1>
Spotted flies will form a more obvious infestation on bitter melon, so prevention and control should be strengthened. In the specific control, the appropriate control method should be reasonably selected in combination with the local soil, climate and crop properties, etc., to improve the killing rate of spotted fly, promote the healthy growth process of crops, and give full play to their ornamental value or commercial value.