Chemical pesticides have been used in agriculture for a long time to control plant pests. However, the use of such chemical goods raises various issues about the influence on human health and the environment. Biopesticides are thought to be safer pest management alternatives to chemical pesticides.
Table of Contents
- What are Biopesticides?
- Types of Biopesticides
- A. Microbial Pesticides
- B. Biochemical pesticides
- C. Plant Incorporated Protectants (PIPS)
- Advantages of Biopesticides
- Disadvantages of Biopesticides
What are Biopesticides?
Biopesticides are compounds derived from natural creatures or substances that are used to manage or inhibit agricultural pests, weeds, and disease-causing agents through particular biological effects. There are numerous definitions of what constitutes a biopesticide.
The US Environmental Protection Agency (EPA) defines biopesticides as "pesticides derived from natural materials such as animals, plants, bacteria, and certain minerals."
Types of Biopesticides
Biopesticides are divided into three types based on their extraction source/origin:
A. Microbial Pesticides
Microbial pesticides are biopesticides generated from microorganisms such as bacteria, viruses, fungi, protozoa, and entomopathogenic nematodes, and are used to control certain plant pests.
Pests are controlled by causing disease, increasing competition for food and space, manufacturing poisonous metabolites, or a variety of other methods.
The following are some major microbial pesticides:
Bacterial biopesticides
- Bacterial biopesticides are the most popular form of microbial pesticides, which are generally used to control insects, although some are also employed against other dangerous bacteria and fungi.
- The entomopathogenic bacterium Bacillus thuringiensis (Bt) Berliner is the most thoroughly researched and commercially utilised biopesticide of the various kinds of bacteria having pesticide action.
- Bacillus subtilis, Pseudomonas fluorescens, Agrobacterium radiobacter, and other frequently used bacterial biopesticides are also employed.
Viral biopesticides
- Several viral families are known to infect insects; however, only viruses from the family Baculoviridae are utilised as insecticides in practise.
- Baculoviruses are a kind of DNA virus with two strands that infect insects. Insects are infected by eating. When swallowed, they penetrate the insect's body and release baculovirus particles, infecting the gut cells. The insect will cease eating after a few days and finally die, releasing virus particles into the environment.
Fungal biopesticides
- Insect control with fungi biopesticides is prevalent. Some fungus can also fight off other fungi, bacteria, and plant diseases.
- Unlike bacterial and viral biopesticides, fungal biopesticides do not require ingestion to produce infection. They can infect pests by either competing for space and nutrition or releasing harmful secondary metabolites that pass through the insect cuticle.
- Beauveria bassiana, Metarhizium anisopliae, Trichoderma viride, Paecilomyces farinosus, and Verticillium lecanii are some of the most extensively utilised fungal biopesticides.
B. Biochemical pesticides
Biochemical pesticides are insecticides generated from natural compounds that use non-toxic approaches to manage pests. Plant extracts, semiochemicals, and growth regulators are the three types.
Plant extracts (Botanicals)
- Botanical biopesticides are a type of biopesticide that is created from plant extracts and essential oils.
- Secondary metabolites that display pesticidal action include steroids, alkaloids, phenolics, terpenoids, and nitrogenated chemicals.
- These chemicals have the potential to act as repellents, growth regulators, and antifeedants. They can also cause metabolic dysfunction by limiting breathing.
- Neem (from Azadirachta indica), Nicotine (from Nicotiana species), Pyrethrum (from Dalmatia pyrethrum), Ryanodine (Rayania; from Ryania speciosa), and other plant-based biopesticides are routinely employed.
Semiochemicals
- These are substances that are produced by plants or animals that elicit behavioural or physiological changes in receptor organisms of the same or other species.
- Plant pests can be controlled by a variety of actions such as mass trapping, lure and kill, mating disruption, push-pull systems, and triggering plant defences.
- Semiochemicals are divided into two types: Allelochemicals and pheromones
- Pheromones, also known as intraspecific semiochemicals, are substances that influence the behaviour of creatures of the same species.
- Allelochemicals, also known as interspecific semiochemicals, alter the behaviour of individuals from different species.
Growth regulators
- Insect growth regulators (IGRs) are pesticides that inhibit insect growth and development. They are effective against a variety of insects, including mosquitoes, fleas, and cockroaches.
- Juvenile hormone analogues (JHAs), ecdysteroids analogues, and chitin synthesis inhibitors are among them. (CSIs).
- JHAs imitate juvenile hormones in insects, which suppress genes that promote adult maturity.
- CSIs prevent the synthesis of chitin, which is a significant component of insect skin.
- Ecdysteroids have a role in the moulting and metamorphosis of insects. They can interfere with the capacity of insects to moult and develop as a biopesticide.
C. Plant Incorporated Protectants (PIPS)
- PIPs are a kind of insecticide generated from genetically engineered plants. They are created by transgenic plants that have been injected with pesticide-active genetic material.
- Bt crops are the most common use of this approach, in which Cry proteins from the soil bacteria Bacillus thuringiensis are transferred into the plants.
- Because of consumer aversion to genetically engineered goods, some governments may not consider PIPs to be biopesticides.
- The RNA interference (RNAi) mechanism has recently been exploited to create a new generation of insecticides. In this case, the pests consume double-stranded RNA, which degrades the bugs' mRNA and consequently slows or kills their growth.
Advantages of Biopesticides
Some advantages of employing biopesticides over typical chemical pesticides include:
- Biopesticides are less hazardous to people and other species and are better for the environment.
- Because they are targeted, they are less likely to damage beneficial creatures.
- There is less chance of pest resistance developing.
- The biodegradability of biopesticides minimises the danger of environmental exposure.
- They are appropriate for Integrated Pest Management (IPM) programmes.
Disadvantages of Biopesticides
Despite their many advantages, biopesticides have yet to displace traditional chemical pesticides. The following are some of the limits and drawbacks of biopesticides:
- They have a limited lifespan.
- Some biopesticides are only effective in specific environmental circumstances.
- They are only effective against specific pest species, hence they only control a subset of pests.
- They may be tough to implement and perplexing to farmers.
- It may take a long time for regulatory organisations to approve it, and the cost of manufacture is expensive.
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