Pest control in agriculture, a process that maintains nuisance organisms below economic thresholds, is a complex ecological process often mediated by biodiversity. Agricultural intensification results in widespread losses of biodiversity, with important implications for pest control.
Pest control in agriculture crops is generally achieved by chemical pesticides which are effective and have a ‘knock-down’ effect on life stages of insects and mites. Recently, plant products have been experimented on in indoor cultivation and in fields. Water extracts and soil application of seed cake are used as traditional measures while essential oils, extracts in organic solvents, and formulations based on pure allelochemicals are marketed products. Neem .Juss.
Derived products are applied extensively in pest control pest control in agricultural crops, and other plants that are readily available locally are being exploited for their actions. The potential benefits are that they are economical, environmentally friendly, effective and of low toxicity to non-target organisms including humans. In the future, integration of plant products in pest management strategies would enhance sustainable organic agriculture and prevent crop loss in terms of both quality and production.
Pest control in agriculture crops of economic interest was based on biological principles that sought to predict the interaction between the host plant and the pest in the ecosystem .After World War II, with the development of synthetic insecticides ,there was a significant global change in the philosophy of pest control, guided by the use of synthetic pesticides that initially had success in controlling several pests.
The intensive and inadequate use of these insecticides significantly reduced the action of natural enemies. It led to the reemergence of primary pests, secondary pest outbreaks, development of resistance to pesticides, and side effects on humans and other animals . Since the 1960s, the use of sustainable alternative techniques has been discussed, and the concept of Integrated Pest Management (IPM) was consolidated with the application of several tactics alternative to chemical pest control in agriculture and the provision of new incentives to research new pest management strategies.
The late 1990s were characterized by major advances in molecular biology through genetic engineering techniques for the development of plants with insect resistance characteristics, such as Bt crops expressing Bacillus thuringiensis Cry toxins and the RNA interference technique which suppresses a target gene and interrupts a vital step in protein synthesis. In recent decades, the Bt crops has been widely used due to many benefits, such as effective control of target insects, decreased use of chemical insecticides, and high specificity, significantly contributing to the increased world production of major crop.
Despite the benefits of crops for pest management, this tactic alone is not sustainable since the development of specimens resistant to these technologies is inevitable and increasingly rapid .The high cost of discovering new insecticide molecules and the growing reports of an arthropod pest population resistant to conventional insecticides are also considered.
In this scenario, compared to chemical insecticides, Bt-based biopesticides stand out for their low cost of development , slower resistance development than Bt crops, and selectivity and specificity.These biopesticides contain mixtures of spores and crystals, which are historically the main microbial products commercialized in the world, used particularly to control lepidopteran pests.
This chapter describes the main aspects that have been addressed by researchers in over 100 years of Bt research, from Cry pesticidal protein characterization responsible for much of the insecticidal activity of this bacterium to its compatibility with other control methods. It concludes with the main challenges Bt biopesticides face to remain and increase their importance in IPM.
In agriculture, horticulture, and forestry
Biological pest control in agriculture
Biological pest control in agriculture is a method of controlling pests such as insects and mites by using other organisms. It relies on predation, parasitism, herbivory, parasitody or other natural mechanisms, but typically also involves an active human management role. Classical biological control involves the introduction of natural enemies of the pest that are bred in the laboratory and released into the environment. An alternative approach is to augment the natural enemies that occur in a particular area by releasing more, either in small, repeated batches, or in a single large-scale release. Ideally, the released organism will breed and survive, and provide long-term control. Biological control can be an important component of an integrated pest management programme.
For example: mosquitoes are often controlled by putting Bt Bacillus thuringiensis ssp. israelensis, a bacterium that infects and kills mosquito larvae, in local water sources
Mechanical pest control in agriculture is the use of hands-on techniques as well as simple equipment and devices, that provides a protective barrier between plants and insects. This is referred to as tillage and is one of the oldest methods of weed control as well as being useful for pest control; wireworms, the larvae of the common click beetle, are very destructive pests of newly ploughed grassland, and repeated cultivation exposes them to the birds and other predators that feed on them.
A trap crop is a crop of a plant that attracts pests, diverting them from nearby crops. Pests aggregated on the trap crop can be more easily controlled using pesticides or other methods. However, trap-cropping, on its own, has often failed to cost effectively reduce pest densities on large commercial scales, without the use of pesticides, possibly due to the pests ability to disperse back into the main field.
Pesticides are applied crops by pest control in agriculture aircraft, tractor-mounted crop sprayers, aerial spray by modern aircraft or as seed dressings to pest control in agriculture pests. However, successful control by pesticides is not easy; the right formulation must be chosen, the timing is often critical, the method of application is important, adequate coverage and retention on the crop are necessary. The killing of natural enemies of the target pest should be minimized. This is particularly important in countries where there are natural reservoirs of pests and their enemies in the countryside surrounding plantation crops, and these co-exist in a delicate balance. Often in less-developed countries, the crops are well adapted to the local situation and no pesticides are needed. Where progressive farmers are using fertilizers to grow improved crop varieties, these are often more susceptible to pest damage, but the indiscriminate application of pesticides may be detrimental in the longer term.
The efficacy of chemical pesticides tends to diminish over time. This is because any organism that manages to survive the initial application will pass on its genes to its offspring and a resistant strain will be developed. In this way, some of the most serious pests have developed resistance and are no longer killed by pesticides that used to kill their ancestors. This necessitates higher concentrations of chemical, more frequent applications and a movement to more expensive formulations.
Pesticides are formulated to kill pests, but many have detrimental effects on non-target species; of particular concern is the damage done to honey-bees, solitary bees and other pollinating insects and in this regard, the time of day when the spray is applied can be important. The widely used neonicotinoids have been banned on flowering crops in some countries because of their effects on bees. Some pesticides may cause cancer and other health problems in humans, as well as being harmful to wildlife.There can be acute effects immediately after exposure or chronic effects after continuous low-level, or occasional exposure.Maximum residue limits for pesticides in foodstuffs and animal feed are set by many nations.