A Description of Biopesticides Derived From Such Natural Materials

What are Biopesticides?

Biopesticides (also known as biological pesticides) are certain types of pesticides derived from such natural materials as animals, plants, bacteria, and certain minerals. For example, garlic, mint, and baking soda all have pesticidal applications and are considered biopesticides. At the end of 1998, there were approximately 175 registered biopesticide active ingredients and 700 products. Biopesticides fall into three major categories:

Microbial pesticides contain a microorganism (bacterium, fungus, virus, protozoan or alga) as the active ingredient. The most widely known microbial pesticides are varieties of the bacterium Bacillus thuringiensis, or Bt, which can control certain insects in cabbage, potatoes, and other crops. Bt produces a protein that is harmful to specific insect pests. Certain other microbial pesticides act by out-competing pest organisms. Microbial pesticides need to be continuously monitored to ensure they do not become capable of harming non-target organisms, including humans.

Microbial and Antimicrobial Pesticides

These are two separate and distinct types of pesticides registered by EPA. Microbial Pesticides are microbes, including bacteria, that help to control insects and weeds, as well as fungi and bacteria that cause plant diseases. These are one type of biopesticide. Antimicrobial Pesticides are pesticides that control unwanted microbes on inanimate objects, in water, and on selected foods under certain circumstances. These pesticides are almost always chemicals, and they act by killing or inactivating microbes that are pests. Antimicrobial pesticides include the disinfectants used in swimming pools, drinking water supplies, and in hospitals to control microbes that can cause disease.

Plant-pesticides are pesticidal substances that plants produce from genetic material that has been added to the plant. For example, scientists can take the gene for the Bt pesticidal protein, and introduce the gene into the plants= own genetic material. Then the plant B instead of the Bt bacterium--manufactures the substance that destroys the pest. Both the protein and its genetic material are regulated by EPA, the plant itself is not regulated.

Biochemical pesticides are naturally occurring substances that control pests by non-toxic mechanisms. Conventional pesticides, by contrast, are synthetic materials that usually kill or inactivate the pest. Biochemical pesticides include substances that interfere with growth or mating, such as plant growth regulators, or substances that repel or attract pests, such as pheromones. Because it is sometimes difficult to determine whether a natural pesticide controls the pest by a nontoxic mode of action, EPA has established a committee to determine whether a pesticide meets the criteria for a biochemical pesticide.

Why Biopesticides?

For human and environmental safety, as well as an alternatives to conventional pesticides.

For example:

  • 25 million cases of acute occupational pesticide poisoning in developing countries each year (WHO, 1990)
  • 14% of all known occupational injuries and 10% of all fatal injuries are caused by pesticides (ILO, 1996)
  • Obsolete pesticides stored in developing countries - 20,000 tonnes in Africa alone

Also, small-scale, local production in developing countries address the increased public awareness of environmental and food safety Fundamental component of Integrated Pest Management;

  • Natural enemies protected
  • Controls pests resistant to conventional pesticides

Biopesticides are pest management tools that are based on beneficial microorganisms (bacteria, viruses, fungi and protozoa), beneficial nematodes or other safe, biologically based active ingredients. Benefits of biopesticides include effective control of insects, plant diseases and weeds, as well as human and environmental safety. Biopesticides also play an important role in providing pest management tools in areas where pesticide resistance, niche markets, and environmental concerns limit the use of chemical pesticide products.

Types of Control

For Insect Control:

  • Bacterias, such as Bacillus thuringiensis, B. sphaericus, B. popilliae, and Serratia entomophila.
  • Viruses, such as nuclear polyhedrosis viruses, granulosis viruses, and non-occluded baculoviruses.
  • Fungi, such as Beauveria, Metarhizium, Entomophaga, Zoopthora, Paecilomyces, and Normuraea.
  • Protozoa, such as Nosema, Thelohania, and Vairimorpha.
  • Entomopathogenic nematodes, such as Steinernema, Heterorhabditis, and Romanomermis.
  • Others, such as pheromones, parasitoids, predators, and microbial by-products.

For Weed Control:

  • Fungi, such as Alternaria, and Collectotrichum.
  • Bacteria, such as Xanthomonas

For Plant Disease Control:

  • Nematode trapping Fungi, Competitive inoculants, composts and soil inoculants, such as Arthrobotrys

The Three Main Approaches to Biological Control

Biological control is, generally, man's use of a specially chosen living organism to control a particular pest. This chosen organism might be a predator, parasite, or disease which will attack the harmful insect. It is a form of manipulating nature to increase a desired effect. A complete Biological Control program may range from choosing a pesticide which will be least harmful to beneficial insects, to raising and releasing one insect to have it attack another, almost like a "living insecticide".

Biological control uses naturally occurring predators, parasites and diseases to control pests. There are three main ways to use these natural enemies against unwanted insect pest populations.

Classical Biological Control (importation) involves traveling to the country or area from which a newly introduced pest originated and returning with some of the natural enemies that attacked it and kept it from being a pest there. New pests are constantly arriving accidentally or intentionally. Sometimes they survive. When they come, their enemies are left behind. If they become a pest, introducing some of their natural enemies can be an important way to reduce the amount of harm they can do.

Augmentation is a method of increasing the population of a natural enemy which attacks a pest. This can be done by mass producing a pest in a laboratory and releasing it into the field at the proper time. Another method of augmentation is breeding a better natural enemy which can attack or find its prey more effectively. Mass rearings can be released at special times when the pest is most susceptible and natural enemies are not yet present, or they can be released in such large numbers that few pests go untouched by their enemies. The augmentation method relies upon continual human management and does not provide a permanent solution unlike the importation or conservation approaches may

Conservation of natural enemies is an important part in any biological control effort. This involves identifying any factors that limit the effectiveness of a particular natural enemy and changing them to help the beneficial species. Conservation of natural enemies involves either reducing factors which interfere with the natural enemies or providing needed resources that help natural enemies.

Some Advantages of Biological Pest Control

Biological control methods can be used as part of an overall integrated pest management (IPM) program to reduce the legal, environmental , and public safety hazards of chemicals. In addition, it may be a more economical alternative to some insecticides. Some biological control measures can actually prevent economic damage to agricultural crops. Unlike most insecticides, biological controls are often very specific for a particular pest. Other helpful insects, animals, or people can go completely unaffected or disturbed by their use. There is less danger of impact on the environment and water quality.

Biopesticides are inherently less harmful than conventional pesticides. They are designed to affect only one specific pest or, in some cases, a few target organisms, in contrast to broad spectrum, conventional pesticides that may affect organisms as different as birds, insects, and mammals. They are effective in very small quantities and often decompose quickly, thereby resulting in lower exposures and largely avoiding the pollution problems caused by conventional pesticides. When used as a component of Integrated Pest Management (IPM) programs, biopesticides can greatly decrease the use of conventional pesticides, while crop yields remain high. To use biopesticides effectively, however, users need to know a great deal about managing pests.

Some Disadvantages of Biological Pest Control

Biological control takes more intensive management and planning. It can take more time, require more record keeping, more patience, and sometimes more education or training. Successful use of biological control requires a greater understanding of the biology of both the pest and its enemies. Many natural enemies are very susceptible to pesticides, and using them successfully in an IPM program takes great care. In some cases, biological control may be more costly than pesticides. Often, the results of using biological control are not as dramatic or quick as the results of pesticide use. Most natural enemies attack only specific types of insects - unlike broad-spectrum insecticides, which may kill a wide range of insects. Though often an advantage, this can also be a disadvantage.

How does EPA encourage the development and use of biopesticides?

In 1994, the Biopesticides and Pollution Prevention Division was established in the Office of Pesticide Programs to facilitate the registration of biopesticides. This Division promotes the use of safer pesticides, including biopesticides, as components of IPM programs. The Division also coordinates the Pesticide Environmental Stewardship Program (PESP).

Since biopesticides tend to pose fewer risks than conventional pesticides, EPA generally requires much less data to register a biopesticide than to register a conventional pesticide. In fact, new biopesticides are often registered in less than a year, compared with an average of more than 3 years for conventional pesticides.

While biopesticides require less data and are registered in less time than conventional pesticides, EPA must always conduct rigorous reviews to ensure that pesticides will not have adverse effects on human health or the environment. For EPA to be sure that a pesticide is safe, the Agency requires that registrants submit a variety of data about the composition, toxicity, degradation, and other characteristics of the pesticide.

Promising biological pesticides:

  • Fungal and bacterial viruses
  • Pantoea herbicola (fireblight)

Large companies have become interested -will genetically modify organisms microorganisms that rapidly colonize plant surfaces:

  • antagonists of pathogens
  • convert good epiphytes to good antagonists or parasites
  • convert good epiphytes to agents that turn on generalized resistance
  • convert pathogens to non pathogens
  • convert ice nucleating bacteria to non nucleators

Facts

Biopesticides are an important group of pesticides that can reduce pesticide risks.

Biopesticides, in general:

  • Have a narrow target range and a very specific mode of action;
  • Are slow acting;
  • Have relatively critical application times;
  • Suppress, rather than eliminate, a pest population;
  • Have limited field persistence and a short shelf life;
  • Are safer to humans and the environment than conventional pesticides;
  • Present no residue problems.
  • Producing a toxin specific to the pest;
  • Causing a disease;
  • Preventing establishment of other microorganisms through competition; or other modes of action.

Conclusion

Biological pesticides is the way of the future in pest control. The man-made pesticides are target specific and will not harm any other organism or the environment. Tests done in laboratories have concluded it to have a very low toxicity to non-toxic. The results may take a little more time than conventional pesticides except biopesticides have a longer span of effectiveness, spanning to almost a year and grows to ensure that the crop (for example) is completely protected. As time progress these biological pesticides will the only agent for pest control.

Reference

  1. http://www.agnr.umd.edu/users/cmrec/97-1nmn8.htm
  2. http://plantpath.ifas.ufl.edu/Plp5102/Lect8text.html
  3. http://pmep.cce.cornell.edu/profiles/miscnews/art-phero-eup-exempt.html
  4. http://ipmwww.ncsu.edu/biocontrol/introduction.html
  5. http://www.biopesticide.org/
  6. http://www.nearctica.com/environ/pest/ipm.htm
  7. http://www.epa.gov/pesticides/citizens/biopesticides.htm
  8. http://208.249.124.180/oecalag/tbio.html
  9. http://hgic.clemson.edu/factsheets/HGIC2756.htm