JK-TK/GRADE-8-TERM-2 huggingface dataset:
Cultural controls are often used when chemical or biological methods have not yet been devised for an injurious species. Cleanup of the sources of infestation and changes in the planting or harvesting time are particularly important when no effective method of killing the pest is known. However, these methods are also used in combination with other controls: 1. Control by Planting Pest Resistant Varieties: Seeds of healthy plants preferably of a resistant variety only should be sown as far as possible. Certain varieties are naturally resistant or less susceptible to insect attack e.g. certain varieties of wild apples are immune to aphid attacks while most of the cultivated varieties are very susceptible. Hence, by interbreeding wild with cultivated variety, a strain can be evolved which yield good fruits and shall also will be immune to pests. 2. Tolerance to Insect Infestation: A variety may be infected by insects yet survive and show less injury than others because of its ability to replace injured parts such as leaves and rootlets. 3. Ploughing in Relation to Insect Control:The plough if used at right time is a good tool for combating many insect pests; it disturbs or kills them, eradicates weeds upon which they might feed and breed, exposes them to natural enemies or to weather control and buries them so deeply that few adults can emerge. A thorough stirring of the soil before planting is an indirect method for controlling the corn root aphids, because, it breaks up ant colonies, kills many aphids and prevents the growth of weeds on which they live until corn roots are available. 4. Clean Cultivation: Clean cultivation means the removal of weeds, plant residues, and other materials from the fields and growing only healthy crops. The destruction of crop residues is a very good preventive measure for controlling certain species of insects e.g. caterpillars or beetles. The elimination of remaining effectively stops further insect breeding by cutting of their food supply and shelter. Many insects infesting crops will develop on weeds which may or may not be related to these crops botanically. Hence, weed control is a good practice for reducing insect infestation. Damage due to Leptocorisa is very serious when paddy fields are surrounded by weeds which provide a good shelter to the pests till the ears have been formed in them.
Many insects infesting crops will develop on weeds which may or may not be related to these crops botanically. Hence, weed control is a good practice for reducing insect infestation. Damage due to Leptocorisa is very serious when paddy fields are surrounded by weeds which provide a good shelter to the pests till the ears have been formed in them. Similarly various species of red hairy caterpillar, Amsacta moorei, Amsacta collaris and other species of this insect are polyphagous and lay eggs on a number of weeds and on emergence the caterpillars feed on the weeds and then migrate to the nearby fields of any crop. 5. Crop Rotation: Crop rotation is effective as preventive measures against insects that feed on relatively few plant species or where the insects are incapable of long distance migration but crop rotation is useless against a general feeder. If one and the same crop is grown every year the insect population is bound to increase due to abundance of food material. On the contrary, if crops are grown in rotation or alternate years e.g. a crop of one plant family followed by that of different family e.g. barley grown in spring may be followed by legumes or pulses and then wheat in winter and so on. The crops of the same family e.g. cotton, and lady s finger okra belonging to the same family Malvaceae must not follow same year. Mixed crops are sometimes useful as pests do not thrive in large number. 6. Flooding or Irrigation: Where water is available, it is sometime possible to destroy insects by flood or irrigation of the field. Flooding rice fields destroys many sugarcane borers. Similarly other burrowing insects e.g. crickets, grasshoppers, beetles and bugs come out of the ground after flooding the fields. They either die their natural death or readily picked up by birds. Ploughing followed by heavy irrigation within 30 days destroys many pink boll worms. The sugarcane and wheat crops can be saved from the attack of termites by irrigation. 7. Fertilizing: Nitrogenous fertilizers in some soils tend to increase the susceptibility of sorghum to damage by attack of some insects. As a result of proper manuring the plant growth is stimulated. The healthy and vigorous plants can easily resist the attack to which the weaklings would have surrendered. 8. Pruning and Thinning: Some pests are normally carried from old crop to the new one.
The healthy and vigorous plants can easily resist the attack to which the weaklings would have surrendered. 8. Pruning and Thinning: Some pests are normally carried from old crop to the new one. Pruning and thinning decrease the intensity of attack. Infested plant shoots and dead hearts must be immediately removed. Ratooning should be avoided and there should be plenty of intervals between harvesting a crop and sowing a new one. 9. Time of Planting and Harvesting: Time of planting and harvesting has great influence on insect infestation e.g. early maturing cotton is not attacked by pink boll worm in areas where moth do not emerge early. Late planted wheat escapes oviposition by hessian flies in America because the plants do not emerge until most of the flies have disappeared as they are very short lived. Similarly early sowing of rice in the Punjab between the 3rd week of May and mid-June is helpful in protecting it from the attack of rice borer, Tryporyza incertulas so the time should be so regulated that the crop may not be worth the attack at the active period of the pests. 10. Closed Season:An insect species limited in its feeding to one crop may be eradicated by not growing this crop for a year or two. This has been done with success in isolated areas for eradicating the pink boll worm. Such a closed season consists in not growing cotton for a period of several months. 11. Destruction of Volunteer Crops: Volunteer crops are those which grow from self-sown seeds, and stubble crops are those which sprout from roots or stubbles stumps , may be a source of insect infestation and they should be destroyed by ploughing or other means. 12. Trap Crop: A trap crop is a small planting often only a few rows, made somewhat earlier than the main planting for the purpose of diverting insects away from the main crop. The trap crop can either be harvested early or cut and used as fodder before a generation of the insect can be completed. Otherwise it will serve as a breeding ground for the pest which will then attack the main crop in large numbers. The plant species used for trap crop should be one that is very attractive to the insect. The preferred host plants can also be grown around the main crop and when the pest has appeared it can be cut and destroyed.
Otherwise it will serve as a breeding ground for the pest which will then attack the main crop in large numbers. The plant species used for trap crop should be one that is very attractive to the insect. The preferred host plants can also be grown around the main crop and when the pest has appeared it can be cut and destroyed. The other methods of cultural control are early cutting of crop, rate and depth of planting, sowing, separation of complimentary host plants, pasturing the heavy infected crops and drying out the soil etc. Physical and Mechanical Control: The protection of crops and foods from insect attack by physical and mechanical means is the simplest and most effective method. Such measures consist of destruction of insects by mechanical means, burning, trapping, protective screens or barriers, use of high or low temperature, soaking in water and drying. 1. Hand Picking: When only a few plants are infected, certain large conspicuous species may be removed from the plants by hand and destroyed just by pressing the abdomen or dipping them in kerosenized water. 2. Mechanical Means: A rotary blow has been found to destroy over 96 of white grubs as well as cut worms, army worms and other caterpillars. The cutting wheel is thirty two inches in diameter and fourteen inches wide and carries sixteen steel blades. It operates by power take off from a tractor at 150 rpm. 3. Trapping: The insects may be turned into a tray by light and baits or the trap may be mobile and drawn across a field. 4. Light Traps: The attraction of nocturnal insects to light is a common observation and the light traps have been invented and tested for killing crop pests. The attractiveness of an artificial light depends upon its candle power and colour. A yellow light will attract 60 fewer insects than a white light of the same candle power and brightness. The insects attracted by light may be destroyed as they hit electric grid or they may be drowned in water and oil after they have been turned into the trap. 5. Bait Traps: Baits are a form of control whereby insects are attracted to a selected spot on which they can be easily removed. Bait traps have been found to be very effective in controlling the nocturnal insects like cockroaches, crickets, caterpillars and nocturnal moths. 6. Temperature Treatments: a Low Temperature Control: Low temperature extremes are fatal to insects of stored grains.
Bait traps have been found to be very effective in controlling the nocturnal insects like cockroaches, crickets, caterpillars and nocturnal moths. 6. Temperature Treatments: a Low Temperature Control: Low temperature extremes are fatal to insects of stored grains. Usually a temperature of 28 C or lower for at least several hours will kill most of the insects. Tribolium confusum can be killed in 24 h when exposed to subzero temperatures. Low temperatures are utilized for the control of insects in mills, warehouses and similar establishments. B High Temperature Control: High temperatures are also fatal to other species and can be used to kill them. Heating cotton seeds to a temperature of 65.5 C for 30 seconds will kill all pink boll worms in the seeds. Temperature of 48.8-51.6 C in all plants of a flour mill for 10-12 h will kill all insects exposed to such temperature. Exposing the infested grains to the sun also kill all the adults of the stored grain insects. 7. Physical Barriers: The protection of crops from insects by barrier is possible in case of crawling and migratory insects. Treated paper barriers and dust barriers are also used. Trenches are also used to stop army worms. Similarly water channels can be used for checking the migration of crawling insects. 8. Burning: Although destroying insects by burning their shelters is sometime practicable, burning pastures and woodland to destroy insects should not be recommended. It has been found that such practices reduce soil fertility and increases soil erosion. Furthermore, it fails to destroy injurious species but does eradicate many beneficial forms. Both cutting away dead hearts and burning them in time save valuable crops from destruction. Burning the field refuse and stubbles, are the other useful ways of pest control. 9. Sieving and Winnowing: It is possible only for domestic purposes. 10. Flooding: It is well known that a large number of insects breed and dwell in the soil, which may be destroyed by flooding the fields with water. There are several other simple methods through which a number of pest infestation can be controlled but the mechanical method of insect pest control involves a lot of labour like shaking the trees and killing the insects either in the larval or adult stages. Biological Control: The term biological control means control of insects by several biological agencies such as parasites, predators and pathogens.
Flooding: It is well known that a large number of insects breed and dwell in the soil, which may be destroyed by flooding the fields with water. There are several other simple methods through which a number of pest infestation can be controlled but the mechanical method of insect pest control involves a lot of labour like shaking the trees and killing the insects either in the larval or adult stages. Biological Control: The term biological control means control of insects by several biological agencies such as parasites, predators and pathogens. The introduction of sterile males in a normal population and use of sex attractants have been reported to bring about effective biological control. The theoretical basis of the biological control defends on the existence of a natural enemy. The effective natural enemy can be deduced to have the following characteristics: i High searching ability, ii High degree of host specificity or preference, iii Good reproductive capacity relative to the host iv Good adaptation to a wide range of environmental conditions. The most essential characteristic is high searching ability. It should be borne in mind that a really effective enemy may be scarce in its native home because it regulates the host population at low level. There usually is one best enemy for each species in a given habitat and one frequently is sufficient for complete biological control, often, however, a second or third enemy species may add to host population regulation and may in fact be necessary to achieve satisfactory biological control. The best enemy species may differ for different host habitats. Hence there is generally no single best natural enemy extending throughout the range of a pest species. With these qualities the introduced natural enemy by itself or in conjunction with other mortality factors is expected to prevent outbreak of the pest species or at least to drop down major population fluctuations. The essential principle of biological control is to maintain a state of biological equilibrium of a living organism. This biological equilibrium is normally maintained by a set of forces called environmental resistance. Often the biological equilibrium of a living organism is disturbed either due to environmental or biotic factors and consequently a particular organism multiplies and spreads in a unlimited manner so as to assume the status of a pest. The inherent ability of an organism to survive and to reproduce within a given time and under optimal environmental conditions is known as biotic potential. Biotic potential is a force opposed to environmental resistance. It takes into account the number of young produced per female in each reproduction, the number of reproduction in a given time and the sex ratio of the species.
The inherent ability of an organism to survive and to reproduce within a given time and under optimal environmental conditions is known as biotic potential. Biotic potential is a force opposed to environmental resistance. It takes into account the number of young produced per female in each reproduction, the number of reproduction in a given time and the sex ratio of the species. Advantages of Biological Control: Only a limited number of introduced pests have been successfully exterminated with chemicals. It would seem wiser in many instances to attempt a biological control programme which might reduce pest populations below the level which causes economic damage. Biological control has the tremendous advantage that, if successful, it becomes self-sustaining and integrated into the normal environment of the control area. If pest populations are reduced to the point where economic damage is negligible, the control programme is a success. Biological controls tend to be particularly useful on low unit-value crops where complete control may not be required or where chemicals are not recommended. Pests of field and forage crops, forests, and range may be economically controlled by biological methods; chemical controls against such pests may be impractical. A biological control destined to be fully effective will be easily and quickly established. If an imported parasite or predator is not established within three years of careful releases under good conditions for its development, the programme may be justifiably discontinued. Types of Biological Control: There are 4 main types of biological control viz.:. I Introduction of parasites, ii Predators, iii Pathogenic organisms such as bacteria, viruses and fungi etc. And iv Removal of fertile males and creating sterility in males by gamma radiation and introducing these sterile males in a normal population. In addition to these 4 main types, there is a fifth type of biological control where the indigenous parasite of the locality is being utilized for this purpose. 1. Parasites: Parasitic insects develop as larvae on or in a single host individual from eggs generally laid on, in or near the host and usually consume all or most of the host body, killing the host and then pupate, either within or outside the host. The free living adult parasite emerges from the pupa and starts the next generation a new by actively searching for host in which to oviposit. They tend to attack only one host stage i.e. eggs, larvae, or pupae, although there is also some overlapping in certain cases, adult insects do not serve as hosts.
The free living adult parasite emerges from the pupa and starts the next generation a new by actively searching for host in which to oviposit. They tend to attack only one host stage i.e. eggs, larvae, or pupae, although there is also some overlapping in certain cases, adult insects do not serve as hosts. Very often life cycles are commonly short, ranging from 10 days to 2 weeks or so in mid-summer but correspondingly longer in cold weather. In general, they all have great potential rates of increase. According to the species one or more parasitic larvae may characteristically develop per host individual, thus we have either solitary or gregarious parasitism. Sometimes two different species of larvae develop from eggs laid in the same host. This is multiple parasitism. There is also ectoparasitism and endoparasitism, depending upon whether the larva develops externally or internally. The major groups occur in two orders of insects viz. Hymenoptera and Diptera. 2. Predators: Predator insects differ from parasitic ones in that the larvae or nymphs, as the case may be, require several to many prey individuals to attain maturity. The adults generally deposit their eggs near the prey population and after hatching the active mobile immature search out and consume prey individuals. This need of larvae or nymphs to search is an important distinction from parasitic forms whose larvae develop on a single host individual and thus have the advantage of not having to discover additional hosts. Adults of many species are also predatory. There may be one or several generations to one of the prey. Larvae and nymphs as well as corresponding adults may be predaceous or only one stage may exhibit the habit. 3. Pathogens: Pathogenic microorganisms attack insects and have life cycles more or less characteristic or similar microorganisms developing in other groups of animals. Insects are probably subject to as wide as variety of disease as are the vertebrates. Except for the fungi, disease organisms gain entry in the host via mouth or the digestive tract, i.e. the insect host must eat plant or other food contaminated with pathogen. In case of fungi, entrance is gained through the insect integument and free water or very high humidity is generally required. Thus, fungi tend to be restricted to moist environments.
The insect host must eat plant or other food contaminated with pathogen. In case of fungi, entrance is gained through the insect integument and free water or very high humidity is generally required. Thus, fungi tend to be restricted to moist environments. However, fungi do have advantage of attacking sucking insects which because of the nature of their feeding on sap, tend to be fairly free of disease caused by microorganisms because they rarely ingest them. Virtually no insect disease organisms occur in mammals and none have been recorded from man. Thus they are safe to use in biological control even in large scale microbial spraying operations. 4. Genetic Methods: Genetic pest control implies the manipulation and use of genetic material in a manner injurious to pest insects. The control of insect pest populations by the release of sterile males has been demonstrated with at least five insect species. This spectacular technique has been termed autocidal control and involves using an insect species to bring about its own self-destruction. It is accomplished by irradiating laboratory reared males of the species to an extent sufficient to disrupt the genetic function of the sperm nucleus but not appreciably interfere with the normal ability of the male to mate or of the sperm to penetrate the egg of the female. However, such fertilized eggs fail to develop so a wild female mated with a sterilized male produces no progeny. If sterile males are released in large enough number in relation to the wild population they will fertilize more females than will the wild males. The advantage is cumulative in each generation hence eradication may be achieved within a few generations under ideal conditions. The boll weevil is reported to have been eradicated from a small isolated field by the release of chemically sterilized males. Chemosterilants have been under intensive investigation but are not as yet practical. They offer the advantage of treating the wild population directly and thus avoiding the mass rearing necessary with gamma radiation. Use of Pheromones: The ability of an insect to locate a mate and to copulate once it has been found is often directed by natural specific chemicals produced by the insect called pheromones. Natural chemical attractants and mating stimulants have been shown to occur in many pest insects. They are often effective in incredibly small concentrations; one caged virgin female of the introduced pine sawfly attracted over 11000 males. Some have been chemically identified and even synthesized. Its high specificity for particular target insects however makes this approach highly desirable.