Why is the Swedish fly dangerous on winter wheat and how to deal with it and other cereal pests

The Swedish fly causes great serious damage to agriculture, destroying cereals and forage crops. This insect adapts to any environmental conditions: thanks to its high adaptive abilities, it has spread throughout the globe and is found even in the Arctic. Only a carefully thought-out system of measures to protect crops and mature plants helps defeat this dangerous pest.

What kind of pest is this

The Swedish fly is a representative of the cereal fly family Chloropidae (order Diptera). It was first described in Sweden by the first taxonomist Carl Linnaeus (1756). About 30 species of this insect are now known.

What does it look like

The adult has an elongated body measuring 1.5-2.5 mm and black in color.. The female's abdomen is thicker and ends with a narrow ovipositor. The scutellum is rounded, the dorsum is slightly convex and smooth.

The wings are small transparent with a metallic sheen. On the head there is a small proboscis and black antennae.

Why is it dangerous for winter wheat?

The Swedish fly causes the main damage to winter wheat in autumn.. Emerging at the end of September, the females lay eggs in the leaf axils of young shoots during the period when the second leaf emerges. Then egg laying stops and usually stops after 50% of the third leaf has reached.

The hatched voracious larvae, which are twice the size of an adult, penetrate the shoots at the base of the stem.There they eat upward, reaching the ear bud, and eat it and the milk grains.

If the Swedish fly larvae damage the main stem, the crop dies, due to which the percentage of yield is significantly reduced - by 50%.

Reference! Swedish fly larvae damage about 20 species of cultivated and 46 species of wild cereals.

Reproduction and life cycle

Pests reproduce so quickly that they manage to produce up to 5 generations of individuals in one season. in favorable weather. The female carefully chooses a suitable place. First, it checks all the stems, stroking them with its antennae, and then lays eggs in cereal plants that have reached a certain stage of the growing season. The size of the eggs is 0.7-0.8 mm.

The larvae develop inside the egg in approximately eight days., then go out in search of food. With the help of special salivary glands that secrete a specific enzyme for the breakdown of plant tissue, the rudiments of future wheat grains are absorbed.

In nature, the life cycle of larvae is about a month. with sufficient nutrition, in laboratory conditions - up to 40 days. They can survive without food for a maximum of seven days.

The insect spends the winter in hibernation in the form of a pupa in the stubble of perennial cereals and on winter crop seedlings. Activates with the arrival of spring at temperatures above +12°C.

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Reasons for appearance

The main reason for its widespread appearance is its ability to adapt to different climates.. There are other factors that contribute to the spread of the population on winter wheat:

1. Long warm autumn. The period of pest activity increases (at a temperature of +10°C, the insect already goes into hibernation).
2. Aridity. Dry weather promotes active growth and development of larvae.
3. Food conditions for the growth of winter crops. The more food that enters the plant, the stronger it is, and the stages of development occur much faster. Consequently, the Swedish fly’s period of eating the plant is reduced, since it causes damage at a certain phase of the crop’s growing season.
4. Favorable temperature for the period of larval growth (above +10 °C).
5. An insect's ability to migrate over long distances.

Symptoms of the lesion

First of all, the larvae influence the development of the stem. The central leaf withers and turns yellow, sometimes it is completely absent: it either falls off or does not come out of the leaf sinus. External signs of damage caused by the Swedish fly, are revealed approximately two weeks from the settlement of the larvae.

The plant tries to direct forces to the damaged areas, so the color of the leaves becomes intense green and the stems thicken. Using this feature, specialists accurately determine the presence of the Swedish fly in wheat fields.

Fighting methods

The damage caused by insects can be significantly reduced with the correct choice of means of combating it.

Agrotechnical

The most effective ways:

1. Compliance with crop rotation. The best predecessors: legumes (clover, alfalfa, peas, soybeans, vetch-oat mixture), corn, annual grasses except sorghum and Sudan grass. It is not advisable to sow wheat on one plot for more than two years.
2. Selection of sustainable seed material with strong fiber that protects the ear from damage by larvae.
3. Sowing late varieties (for example, Mirostan, Chaus, Krasnodol) at the optimal time so that winter crops begin to rise with the onset of frost, when flies hibernate.
4. Increasing seeding rate grain, so that out of the number of sprouted ears, most of them survive and the harvest remains at the same level.
5. Deep plowing soil.
6. Application of nitrogen fertilizers on fields with winter crops to increase plant viability.

Chemical

During the period of egg laying and mass summer, chemical treatment of wheat is carried out. Using aviation, winter crops are pollinated when their development is in the first leaf phase. In many areas, 12% hexachlorane dust is widely used.

The population of harmful insects is reduced when spraying plants with organochlorine and organophosphorus agents. Insecticidal preparations are also used, for example, “Cruiser” and “Celest Top”.

Attention! The death of the fly after treatment reaches 93%, the yield increases by 20% or more.

Preventive measures

To obtain a high yield you need preventive actions:

1. Timely peeling stubble to destroy the pest and its larvae.
2. Sowing high-grade calibrated seeds. They produce friendly and strong shoots, and these are more resistant to the attacks of the Swedish fly.
3. Grain pickling before sowing into the soil. The drugs “Gaucho” and “Cruiser” are used.
4. Crops with grain crops preferably placed after legumes or row crops.

Read also:

Fertilizers for winter wheat: what to feed in the fall

Stages of sowing winter wheat and caring for plantings

Guide to using wheat as green manure

Other pests of winter wheat in seeds, plantings and warehouses

The number of cereal pests is very large. Let's talk about those causing the greatest harm.

bug turtle

The insect prefers to feed mainly on wheat, damaging crops of both winter and spring crops. Externally it looks like a tiny turtle. The development cycle of the bug is directly related to the growing season of cereals, so throughout the entire summer period the turtle leads an active lifestyle, causing significant damage both in the fields and in storage facilities.

Trips

Wheat thrips damages winter and spring wheat, as well as some cereal perennial grasses. Both adults and larvae are harmful. The insect feeds on fresh juice from the spike scales or from a young succulent leaf, as a result of which the cereal stops growing.

The grains in the ear receive severe damage - they become chipped and defective, which affects the overall quality of the seed. Externally, thrips is a small black-brown fly with poorly developed wings and a size of 1.3-1.5 mm.

Ground beetle

The bread ground beetle causes the greatest damage to winter wheat.. The larvae of this pest begin their activity during the period of rising and beginning of tillering of seedlings. They eat leaves and young stems, turning wheat bushes into soaked fiber. Adult beetles infect the ears. They gnaw the scales of the ear, the rudiments of the grains, and gnaw out the ripening grains.

Insect size – 12-17 mm, color – pitch black with a bronze tint. The head is large, the antennae are short, the elytra are convex with deep punctate grooves.

Weevil

The bug's mouthparts are an elongated proboscis.. With its help, the insect destroys the dense skin of grain or cereal.The weevil is considered one of the main and most dangerous pests of grain crops - wheat, barley, buckwheat, corn, as well as pasta; it destroys stocks both in the kitchen and in huge grain storage facilities.

The insect has an elongated body measuring about 4 mm, dark brown, almost black in color.. If it has wings, it is not adapted for flight, but it moves long distances on ships and trains carrying industrial batches of grain.

How to deal with wheat pests

Measures to combat the listed pests and preventive procedures are carried out approximately the same and include:

1. Agrotechnical measures: stubble peeling and deep fall plowing, compliance with crop rotation and sowing dates, growing resistant varieties.
2. Chemical: spraying grain with approved types of insecticides, for example, “Karate”, “Arrivo”, “Fastak”, “Aktelik”.
3. Preventive: before storing in storage, treat grain with agents based on carbendazim, mancozeb, triticonazole. And also maximum drying of the product, thorough cleaning of the room, disinfection of the storage, for example, with formaldehyde vapor (after this, the storage is kept hermetically sealed for 2-3 days, then thoroughly ventilated).

Conclusion

The Swedish fly and other insects that feed on winter wheat varieties can completely destroy the crop without timely protective measures. To prevent crop loss, specialists jointly carry out agrotechnical, chemical and preventive methods of pest control both in the fields and in grain storage facilities.