Mechanical and physical pest control methods

Mechanical pest control measures include various methods of collecting or destroying insects in the crop or the use of certain mechanical barriers. Some mechanical pest control measures are implemented when the pests infest the host plant and aim to maintain yields, while other measures are implemented when vegetation is dormant or when the pest is not causing direct damage to the crop and aim to reduce the pest population in the future. Examples of some mechanical control measures are given in Table 3.3. and the possible implementation of a particular measure for other crops or pests is described.

Table 3.3 Some examples of mechanical pest control measures

Method	Target pest	How to implement it	Additional comments and possible implementation
Destroying crop residues	Ostrinia nubilalis	It is applied after harvest. Corn in which caterpillars overwinter is crushed into pieces shorter than 1 cm using specially designed equipment.	The destruction of plant remains may still be accomplished by chopping, burning, or deep plowing. This measure is acceptable for several other pests. In greenhouse production, destruction of plant residues is necessary. Leaf miners that pupate in the leaf are suppressed by collecting and burning fallen leaves.
Collecting and destroying the insects	Leptinotarsa decemlineata	At the time of emergence of the adult beetles, they are collected and mechanically destroyed (clearly visible on the plants). Leaves on which eggs are laid are also collected. Collection should be carried out at least twice a week at the time of emergence of overwintering adult beetles.	Manual collection can be done for pests with larger body sizes (e.g., weevils on grapevines), for pests that are held together (e.g., caterpillar cocoons on branches), or when the egg clutches of the pest are collected. In some cases, the pests are collected with the parts of the plant (e.g. leaves, twigs) that they infest. Mechanical collection is carried out with aspirators and in this case, in addition to the pests, their natural enemies are also collected - these should be returned to nature after collection. The obligatory measure after collecting is the destruction of the collected pests.
Collecting the pests by using different tools	Cydia pomonella, wasps, horns, rodentia, crockroaches	Mechanical trapping of pests is carried out with the aid of various aids, which may be hunting belts of corrugated cardboard, hunting vessels filled with a mixture of water, vinegar, etc., or specially constructed traps.	Hunting belts of corrugated cardboard placed around the trunk in early fall to catch overwintering codling moth caterpillars. They are also suitable for other caterpillar species that overwinter on the trunk. Hunting pots or traps are placed in areas accessible to insects and some form of bait can be placed in them to attract the target organism. See Table 3.4. Suitable for a wide range of pests.
Mechanical barriers	Slugs, Bothynoderes punctiventris, wild animals, aphids, rodents	Various types of barriers, such as mechanical barriers for slugs, fences for wildlife, barriers (digging channels) to prevent migrating insects from infesting the field (weevils), nets attached to windows and entrances of greenhouses or warehouses, nets or other materials used to cover crops, wrap plants, etc.	Suitable for a large number of pests. It is necessary to choose the best type of barrier according to the type of pest and its way of life and the characteristics of the plants.

Physical control methods involve the use of physical means to control pests. These include the use of temperature (low or high), humidity, carbon dioxide, vacuuming, and the use of optical and olfactory baits, gamma rays, ozone, etc. High and low temperatures are most commonly used for pest control in protected areas (e.g. steam sterilization of floors) or in warehouses during food storage (e.g. freezing beans to control pea weevil). A brief overview of the most common physical methods and possible applications is given in Table 3.4.

Table 3.4 Examples of the use of physical pest control methods

Method	Target pest	Description	Wider implementation
Soil sterilization by steam	Pests, diseases and weeds in protected areas in the soil (nematodes, fly larvae, spores of various fungi, weed seeds)	Hot steam is introduced through perforated pipes into empty greenhouses or sheltered areas. It is produced in a specially constructed apparatus. Under the influence of the steam, the soil temperature rises to such an extent that survival of organisms in the soil is no longer possible. In carrying out the procedure, it is important to ensure a certain period of time during which the temperature is elevated, i.e. the organisms must be exposed to the target temperature for a certain period of time. The lower the target temperature, the longer the exposure can be. It is recommended to heat the soil to 95 ° C for 5 minutes.	The method is applicable to all protected areas and to almost all harmful organisms present in the soil at the time the method is carried out.
Solarization	Nematodes in vegetables and ornamental plants	During the summer months, when there is no cultivation on certain areas, the soil is covered with a transparent plastic foil (PE or PVC) 0.015-0.05 mm thick. The soil remains covered for 1-2 months. Before covering the soil should be moistened. Soil temperatures at a depth of 10 cm under the foil are raised by 10-20 ° C in relation to the uncovered soil. This is enough to destroy organisms (nematodes, fungi, weed seeds) in the soil.	Applicable to all groups of harmful organisms in conditions where it is possible to leave the plots unsown during the summer months.
Vacuum and Carbon dioxide	Stored product pests	The method is based on removing the air from the warehouses where grain products are stored, creating a vacuum and causing the pests to die under such conditions. Another option is the introduction of carbon dioxide into the storage room, which displaces the air and the pests die due to the lack of oxygen. The implementation of these methods is possible in warehouses that are designed to be completely sealed.	Applicable to all groups of harmful organisms in storage areas.
Ozon	Stored product pests	Introduction of ozone produced for this purpose in devices (ozonators) in warehouses. To achieve full success it is necessary to achieve a certain concentration of ozone in a certain period of time depending on the type of insect.	Research on different ways of using ozone is underway.
Sterilization of males by gamma rays	Ceratitis capitata, Dacus oleae	This method is also referred to as SIT technology. Gamma rays are used to sterilize mass bred male fruit flies and then release them into plantations where they compete with fertile males for females to copulate with. After a female copulates with a sterile male, she does not produce eggs, so the released sterilized males reduce the number of eggs laid and the number of larvae that cause damage. Sterile males are usually released over a geographically larger area (area-wide management).	Suitable for other types of fruit flies (e.g. olive fruit fly) and is also used worldwide for insects that attack humans (mosquitoes, cannibal flies, etc.)
Mass trapping using colored sticky traps	Aphids, white flies	A large number of yellow plates are placed on the edges of greenhouses or protected areas. The plates are placed so that the lower edge of the plate is flush with the top of the crop. The aim is to catch a larger number of aphids as they fly into the building. The yellow plates must be replaced regularly to ensure the capacity of the adhesive surface.	Besides aphids, the method is also suitable for moths, thrips, fruit flies, vegetable flies, etc. The color of the sticky board adapts to the type of pest.
Confusion by sexual pheromones	Grapevine moths	Pheromone capsules (without traps) are placed in large numbers in plantations. The pheromone capsules release a high concentration of female pheromones, confusing the males and making it impossible for them to find the females. Therefore, they do not mate. Unfertilized females do not lay eggs, so caterpillar infestation is reduced.	Also suitable for codling moth, South American tomato moth and some other species that produce pheromones.