What is the danger of pea bruchus and how to save the crop?

Each gardener who grows peas on his plot, is likely to encounter such a common pest as bruchus. It is also sometimes called pea seed, emphasizing the love of the beetle to this culture. The main harm is caused by larvae that feed on nutritious beans - these are plants, while adults prefer flower pollen. A sure sign of the "work" of Bruchus is small holes in the fruits of peas that appear during storage.

Meet the insect

Bruchus belongs to the family of beetle seeds, which in Latin is called Coleoptera. It has small dimensions: the body length of adults in the adult development phase is usually 0.4–0.5 mm.

In the photo of the bruchus, under the magnification, 11-membered antennae and 2 pairs of legs are visible, the first of which are turned forward, and the rest are turned back.

The body of the beetle is covered with small gray hairs, although black itself. The legs and antennae differ in color: they are partially yellow, often with a reddish tint. The head of the bruchus is relatively small. The pronotum is protected by a shield, and on the elytra of this beetle there are white spots resembling a cross in shape. This special pattern is a distinctive feature of bruchus from other millstones.

The head of the beetle has an elongated shape, which makes it look like a weevil. In English, the insect is called “pea weevil” (pea weevil), which is incorrect from the point of view of biological classification ...

Bruchus life

Bruchus is a beetle whose southern homeland with a warm climate became its historical homeland. But today it is a cosmopolitan insect that has successfully settled in the territories of the whole world where its favorite food, peas, is grown. The habitat has changed, according to biologists, due to human activities, which transported bruchus from continent to continent, along with legumes.

This species can be called "monogamous" in the choice of food, although they also spread over territories with stocks of crops similar to peas: beans, vetch, chickpea, lentils, beans, etc. But female bruchus never lay their larvae eating fruits, on these plants. Therefore, this pest does not threaten other legumes, unlike peas.

Wintering

Bruchus, because of its southern origin, can hardly tolerate winter frosts. In central Russia and neighboring countries, larvae and beetles wait for adverse weather in insulated barns, warehouses, granaries, waiting for the spring sun to warm up the air. They hide in nooks, crevices of the floor or walls.

In regions with a warmer climate, the picture is different: beetles leave the peas in the autumn months. To winter, bruchus selects fallen leaves, hay and straw for shelter. Some individuals even go straight to the pea fields, fleeing the cold snap in the plant debris left after harvesting.

A new stage in the life of Bruchus begins at the end of April-May, when the bugs leave their shelters, flying around.They prefer areas that are well lit by the sun's rays: gardens, fields, kitchen gardens, forest belts. Only part of the pest falls into the areas where peas are cultivated, along with planting material: most insects fly here in search of food after wintering. Bruchus feed on pollen and particles of pea flower petals.

Pea weevil is very sensitive to weather. She tries to get inside the flower, where the wind does not bother her.

Bruchus are very thermophilic creatures. Therefore, they are especially active in hot and sunny weather. If it starts to rain, they hide from the weather between the leaves and the petals and wait for the rain to end.

The life expectancy of pea weevil depends on the climatic conditions of the region. So, in the southern regions lives up to 3 years, and in the northern latitudes this figure does not exceed 1 year, because it is very difficult for individuals to survive frosts.

Breeding

In regions with a warm climate, the laying time of female Bruchus eggs begins in June. In the temperate and northern latitudes, this period moves back about a month later. To create the masonry, a pea weevil tries to choose the largest plants, with well-developed stems stretching in height.

Beetles in search of peas often fly 3 km.

The female attaches the eggs to the surface of the plant using a special mass with a liquid and sticky consistency. Such a composition is produced in a beetle in special glands. In air, the mass dries quickly, forming a crust of small diameter, difficult to distinguish with the naked eye. Under such a protective shelter is an egg of elongated elliptical shape, painted in amber color. Its microscopic dimensions are not more than 0.5 mm. The egg is so firmly fixed to the surface of the pea that it cannot be torn by heavy rain and wind.

The appearance of larvae from an egg will occur 8 to 12 days after the masonry is created.

Bruchus are very prolific. The female is able to lay 70 - 200 eggs during the summer. On one plant, their number can reach 35, but when the larvae are born, each of them occupies a separate bean.

Bruchus larva

Bruchus on peas harms plantings, being in a state of larva. In the first cycles of its development, it has a reddish torso with three pairs of legs. On it is a drawing similar to the letter “H”. As it approaches the transformation into the pupal phase, accompanied by molting, the larva acquires a thick and curved shape, and its body becomes a white-cream hue.

Bruchus larvae give preference to mature and dried pea seeds. This is characteristic of most pests that attack bean plantings.

Peas are required to feed an intensely growing larva. She eats her cotyledons, eventually growing to 6 mm in length. When the future bruchus leaves its nutrient-rich shelter - it depends on the climatic conditions of the environment. In the southern regions, the larva shortly after the cessation of its development leaves the pea grain in the form of adults, while in areas with a cold climate it remains to winter in it in order to protect itself from harmful frosts. This prudence provides not only the excellent survival of the Bruchus larvae and population increase, but also the extensive resettlement in the nearby territories where it is brought along with peas.

Inside the beans, the larva receives what it needs to develop: a shelter from external dangers and food. In peas, the entire conversion cycle to an adult occurs. During this time, the larvae have time to shed several times. When the time comes to transform into a chrysalis, they gnaw at the bean, leaving the last barrier - the pea shell. The entire development of the larva takes approximately 1.5 months.

Dolly and Bruchus imago

Pupa size does not differ from adult larva - 0.5–0.6 mm.In appearance, it is already completely similar to the imago - the final stage of development, but continues to be in a pea. At the time of her rebirth in the imago, she will need three weeks.

Under favorable conditions, adults leave their temporary home in mid-August or autumn. To do this, the beetle gnaws the pea shell, leaving a hole in it, which later blackens. Its diameter is only 0.3 mm.

If the bruchus feels the approach of cold weather, then he remains in his shelter to winter.

Bruchus as an agricultural pest

Bruchus larvae do tremendous damage to the crop. Investigations by agronomists have shown that if they become infected, the collected peas lose 35% of their normal mass. But the harm of pea grains does not end there either: the affected beans significantly lose their germination percentage and even become unfit for human and animal consumption. The fact is that the excrement of larvae of Bruchus contains the alkaloid canaridin, which is a toxic substance for mammals. The consequences of its use are poisoning the body.

Ways to fight

If bruchuses appeared on the site, then a solution to the problem should be approached immediately. Effective folk remedies against this pest do not exist - you will need "heavy" artillery in the form of chemicals (insecticides). Agrotechnical methods that can also be used as preventive measures will help reduce the risk of infection and prevent re-infection.

Special tools

The karbofos solution prepared at the rate of 60 g per 10 l of water copes well with the population of bruchus who have chosen planted peas. The resulting composition is sprayed with flowering plants. One treatment will not be enough - you will need three procedures carried out with a difference of a week. You can also use the universal insecticide "Aktara", which, according to observations, reduces the number of pea kernels by 4 times.

In agriculture, in addition to spraying peas with insecticides, apply:

• gas disinfection;
• storage processing;
• the use of drugs based on hydrogen phosphorus (fumigation).

Chemical preparations should be used very carefully due to their high toxicity, so that the crop is safe to eat after processing plants. Also for this reason, when applying chemicals, you must strictly follow the instructions and safety precautions.

Another specific way to deal with bruchus is to freeze peas and other legumes in a freezer. Grain is unable to survive low temperatures for a long time. Therefore, when storing the crop at home, it is recommended to put it in the freezer for 2 weeks, and with the onset of stable subzero temperatures, place it on the balcony or in the room without heating. Before cooking the beans, just warm them up at 60 ° C.

Prevention

To significantly reduce the risk of a beam on pea plantings, you need to follow some rules:

1. Observe crop rotation by changing the landing site.
2. Carefully inspect the seeds and plant only healthy ones.
3. If necessary, hull peas, loosen and fertilize the soil.
4. After harvesting, remove all plant debris and plant debris.
5. Dig the soil deep in the autumn.

To check the beans for infection, you need to dip the peas in a solution of sodium chloride. Those that float to its surface cannot be planted.

Bruchus is a pest that causes pea irreparable harm and makes the crop unsuitable for consumption. To avoid this, it is important to carefully treat the seeds, the rules for caring for the site. If infection has already occurred, the fight will be effective with the help of chemicals.