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Objectives: to introduce students to appearance especially dangerous insect pests of gardens and forests, talk about their harm and measures to help reduce their numbers.

Equipment: table “Insects – pests of gardens and forests”; individual drawings of insect development for mounting on a wall board; collection material.

Methods and teaching techniques: a teacher’s story with elements of conversation using visual arts visual aids, independent work students with a textbook.

During the classes

It is advisable to start the lesson with a condensed test of students’ knowledge: an individual oral test on insect pests of fields and gardens and an individual written test (using flashcards) on arthropods.

Questions for oral knowledge testing:

1. What harm do locusts and mole crickets cause?

2. What are the dangers of aphids and pest bugs and which plants are they harmful to?

3. What harm do beet weevils and Colorado potato beetles cause in fields and gardens?

4. What damage do the cabbage butterfly and the fall armyworm butterfly cause to fields and vegetable gardens?

For a written test of knowledge, you can use the cards that were offered in previous lessons. Having clarified and specified the students’ answers, the teacher shows images of garden pests and invites students to say what these insects are called, which of them they saw alive, and what harm each of them causes to humans. Students are unlikely to be able to give complete answers, so the teacher himself then explains that often during the flowering of apple trees, many buds do not open, the flowers turn brown, and if such a bud is opened, it contains the larva or pupa of the apple flower beetle. It is noteworthy that many of the resulting apples fall off prematurely, each of them has a wormhole, and in the cut apple you can see the caterpillar of the codling moth butterfly.

Afterwards, the teacher tells that during the flowering of strawberries, many of their flower stalks are drooping, as if cut, the ripening fruits of raspberries and currants are “wormy”; shows images of affected plants and the insects associated with such lesions.

Noting that aphids and many other insects cause great harm in gardens, the teacher shows an image of a gypsy moth and tells why this butterfly is so named, why it is dangerous, at what stage it overwinters, and by what signs one can recognize its oviposition.

Among other dangerous insect pests of the forest, the teacher introduces students to the pine silkworm butterfly, bark beetles, longhorned beetles, and talks about the damage caused to forests by the cockchafer.

Having reported that agriculture and forestry in our country are damaged by about 700 species of insect pests, the teacher names mechanical, agrotechnical, chemical and biological methods of combating them. Invites students to tell which of these methods help reduce the number of insects already known to them: locusts, pest bugs, apple blossom beetles, raspberry beetles, gooseberry moths, gypsy moths, etc.

After clarifying and supplementing the students’ answers, the teacher asks the question: what methods of controlling insect pests are most effective and why?

Afterwards, the teacher gives homework: read the text of the paragraph in the textbook and answer the questions; Fill out the table “Insects - pests of gardens and forests” in your notebook (name of insect pests, their belonging to the order, damage caused), reveal the content of the concepts: “methods for reducing the number of insect pests” (mechanical, agrotechnical, chemical, biological).

Task 1. Fill out the table.

Features of the development of insect pests.

View	Group	Overwintering stage of development	Wintering place	Larval nutrition
Cabbage white	Lepidoptera	doll	trees and soil	above ground parts of plants
Beet weevil	Coleoptera	doll	the soil	plant roots
Colorado beetle	Coleoptera	doll	the soil	plant roots
codling moth	Lepidoptera	caterpillar in cocoon	fruit storage	plants, apples, quince
Apple flower beetle	Coleoptera	caterpillar in cocoon	fallen leaves	bud juice, apple buds
Chafer	Coleoptera	doll	the soil	roots of trees, plants
Gypsy moth	Lepidoptera	egg	depressions of the cortex	leaves
Pine silkworm	Lepidoptera	egg	trunks and stumps	plant juice

Task 2. Ten Colorado potato beetles eat 2000 sq.cm of potato leaves within 30 days. During its development, the Colorado potato beetle larva eats approximately 50 square cm of potato leaves. Calculate and record the area of ​​potato leaves that 1,000 Colorado potato beetles will eat. How many larvae of this beetle can destroy the same area of ​​leaves? Based on the above calculations, draw a conclusion about the effect of the Colorado potato beetle on potato yields.

10 beetles = 2000 sq.cm

1000 zhov - x sq.cm

x = 1000*2000/10 = 20,000 sq. cm - the area that will be eaten by 20,000/50 = 400 larvae.

Task 3. Complete the diagram.

Methods for reducing the number of insect pests:

1. Chemical: spraying with pesticides, poisonous baits, treatment with bleach, treatment of plants with poison.

2. Physical: collecting pests, catching with special devices, killing malaria mosquito larvae using kerosene.

3. Agrotechnical: sowing and planting of plants is carried out in such a way that they have time to get stronger by the time the pests appear.

Task 4. Fill out the table.

Insects are carriers of pathogens.

Task 5. Housefly reproduces very quickly. For example, one fly lays approximately 120 eggs at a time. Over the course of the summer, seven generations of flies may appear, about half of which are females. Do the math and write down why this doesn't actually happen.

We will take April 15 as the beginning of the first clutch and assume that the female fly will grow enough in 20 days to be able to lay eggs. Then reproduction will occur as follows: April 15 - the female lays 120 eggs; at the beginning of May, 120 flies grew, of which 60 were females; May 5 - each female lays 120 eggs; in mid-May 120*60=7200 flies emerge, of which 3500 are females, etc.

In fact, this does not happen because many individuals die as a result of natural selection.

Measures to reduce the number of insect pests.

On the territory of our country there are about 700 species of insects - dangerous pests of agriculture and forestry. To reduce their numbers, they are used various ways: mechanical (crushing the eggs of the cabbage butterfly, destroying beet weevils in trapping ditches, etc.), agrotechnical (sowing or planting plants so that they have time to get stronger and become tougher to the appearance of pests, cleaning the bark on the trunks fruit trees, regular collection of fallen fruits, etc.). When mass reproduction of pests occurs, chemical methods are used: pollination and spraying of plants toxic substances(at the same time, unfortunately, many insects die, earthworms, birds). In our time great importance acquire biological methods of plant protection: protection and attraction of insectivorous birds, bats, use of biological preparations that cause diseases of insect pests, as well as breeding and use of other insects - natural enemies insects that harm plants. In the latter case, some predatory insects, egg eaters and riders are used.

Predatory insects.

Many species of insect predators provide great assistance in controlling the number of plant pests. Predatory beetles ladybugs(seven-spotted, two-spotted, etc.) eat aphids, ground beetles eat various caterpillars. The larvae of these insects are also predators. Red forest ants protect the forest from various insect pests.

Equestrians and egg eaters.

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Biological method pest and disease control

The biological method of pest and disease control also includes the use of biological preparations made from bacteria, fungi and viruses that cause diseases harmful insects or suppress plant pathogens. Also, biological preparations are prepared on the basis of pathogenic bacteria that infect small and large rodents and lead to their illness and death.

The genetic method, based on artificial (chemical or radiation) sterilization of male insect pests, is also widely used as part of the biological method of pest and disease control. Insects sterilized in this way are unable to reproduce and lead to population decline.

A large number of insect pests are destroyed by insectivores predator birds, such as tits, starlings, wagtails and woodpeckers. Attracting birds by arranging various man-made nests, birdhouses, and feeders in winter time contributes to a significant reduction in the number of insect pests. This method of biological pest and disease control does not require large expenses.

Thus, we can conclude that the biological method of controlling pests and diseases is cheap and does not disturb the ecological balance. The use of a biological method of pest and disease control eliminates unnecessary expenses, and from the consequences associated with the chemical control method. Biological preparations are practically safe for humans and for environment. However, the biological method of pest and disease control still requires careful development, since the contribution of the method to plant protection is still not great enough. IN currently, When chemical methods control of plant pests and diseases are becoming more and more costly and labor-intensive, and the benefits they bring are no longer as obvious as the harm caused to the environment, the biological method of controlling plant pests and diseases comes to the fore in terms of prospects. Biological scientists are improving biological products that protect plants, and their distribution has already reached 10% of the world's cultivated area.

Those who care about the environmental cleanliness of the harvest on their site can be recommended to contact the specialized company “Ozelenitel Stroy”, where experienced employees will help you select the necessary biological products for plant protection.

Methods for reducing insect pests

Answers:

To reduce the number of insect pests, various methods are used: MECHANICAL (crushing cabbage butterfly eggs, destroying beet weevils in trapping ditches, etc.), AGROTECHNICAL (sowing or planting plants in such a way that they have time to get stronger and become tougher to the appearance of pests , cleaning the bark on the trunks of fruit trees, regularly collecting fallen fruits, etc.). In case of mass reproduction of pests, they are used CHEMICAL methods: pollination and spraying of plants with toxic substances (in this case, unfortunately, many insects, earthworms, and birds die). Nowadays, BIOLOGICAL methods of plant protection are becoming of great importance: protection and attraction of insectivorous birds, bats, the use of biological preparations that cause diseases of insect pests, as well as the breeding and use of other insects - natural enemies of insects that harm plants. In the latter case, some predatory insects, egg eaters and riders are used.

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