Biological Control Notes

Biological Control

ACTION OF PARASITOIDS, PREDATORS, PATHOGENS AND BENEFICIAL MICROORGANISMS in maintaining another organism’s density lower level than would occur in their absence NATURAL CONTROL strategies that employ biological agents for pest suppression refers to the practice of REARING AND RELEASING NATURAL ENEMIES: parasites, predators, or pathogens. Management activity that is designed to PROTECT OR CONSERVE NATURAL ENEMIES. The use of LIVING ORGANISMS to suppress the population of a specific pest organism, making it less abundant or less damaging than it would otherwise be. The précised use of “NATURAL ENEMIES” to maintain phytophagous pest populations within acceptable limits. BIOLOGICAL CONTROL.

History of Biological Control

  • 200 A.D. to 1200 A.D:
    • Chinese were the first to use natural enemies to control insect pests.
    • Nests of the ant Oecophylla smaragdina were sold near Canton in the 3rd century for use in control of citrus insect pests such as Tesseratoma papillosa (Lepidoptera).
  • 1300 A.D. to 1799 A.D
    • Control of the bedbug, Cimex lectularius, was successfully accomplished by releases of the predatory pentatomid Picromerus bidens in 1776 in Europe.
  • 1850 to 1887
    • Trichogramma sp. (egg parasites) were shipped from the U.S. to Canada for control of lepidopterous pests in 1882.
  • 1888 to 1889
    • The vedalia beetle controls the scale mainly in the inland desert areas and C. iceryae controls it in the coastal areas of California.
  • 4,000 years ago
    • Egypt used cats as the first Biological Control for rodents.
  • 1849
    • Chinese Starling was introduced in the Philippines by Governor Martines to control the migratory locust infestation.
  • 1873
    • First international shipment of an insect as a biological control agent was made by CharlesV Riley.
    • Shipping to France the predatory mites to help fight grape vine disease agent Phylloxera.
    • Charles Valentine Riley (birthyear) “Father of Modern Biological Control” and the first person who import mites to control grapevine Phylloxera.

AGENTS IN BIOLOGICAL CONTROL

  • Parasitoid
    • An insect parasite of an arthropod.
    • Parasitic only in immature stages.
    • Destroys its host in the process of development and free living as an adult.
    • Organisms that complete their development on or within another organism (the host).
    • Usually smaller than their selected host.
    • Very selective and only attack a particular life stage.
    • Only female parasitoids are involved in finding and using the host.
    • Generally, the host does not die until the young are fully grown and ready to become adults. At last, hosts are killed.
    • Example: Diadegma semiclausum parasitizing the diamond back moth larvae.
    • Example: Trichogramma against corn borers.
  • Predators
    • Animals that attack and consume other animals as food.
    • Mainly free-living species that directly consume many preys during their whole lifetime.
  • Pathogens
    • Microorganisms that are pathologic to their host.
  • Bacteria
    • Used for biological control to infect insects via their digestive tract.
    • Offer only limited options for controlling insects with sucking mouth parts such as aphids and scale insects.
    • Examples:
      • Bacillus thuringiensis is most widely applied species of bacteria used for biological control and it can be used against Lepidoptera, Coleoptera, Diptera.
      • Bacillus Popilliae causes Milky spore of the white grubs of Japanese beetle.
      • Bacillus sphaericus used against Diptera.
  • Entomopathogenic Fungi
    • Used successfully to protect crops from a variety of pests.
    • They can infect a wide range of insect hosts and have a broad host range.
    • Only limited success using Fungi because they are slow to kill their host.
    • Examples:
      • Beauveria bassiana - used to manage a wide variety of insect pests including: White flies, Thrips, Aphids, Weevils.
      • Metarhizium anisopliae produce toxin destruxins used against Beetles, Locusts, and grasshoppers.
      • Trichoderma viride - silver leaf disease of stone fruits caused by Chondrostereum perpureium.
      • Verticillium lecanii - aphids and white flies.
      • Lagenidium giganteum aquatic fungi against mosquito larvae.
      • Aschersonia aleyrodis - against scale insects and white flies.
      • Cordyceps sp. Against arthropods.
  • Nematodes
    • Resides in soil, soft bodied, non-segmented, obligate or facultative parasite on broad range of insects.
    • Introduces new and environmental- friendly way to eliminate plant pest.
    • These harbors gut bacteria which helps in pathogenesis; symbiotic association with bacteria.
  • Nucleopolyhedrovirus (NPV)
    • A lethal disease of insects particularly larvae of certain Lepidoptera and Hymenoptera.
    • Used against cutworm.

TECHNIQUES IN BIOLOGICAL CONTROL

  • IMPORTATION
    • INTRODUCTION AND ESTABLISHMENT OF NATURAL ENEMIES in a new locality where they did not occur or originate naturally.
    • When natural enemies are successfully established, it usually continues to control the pest population.
    • Example: One of the earliest success in west was in controlling Icerya purchasi (cottony cushion scale) in Australia using a predatory insect Rodolia cardinalis (vadalia beetle).
    • Parasitoid wasps Trichogramma ostriniae to control European corn borer Ostrinia nubilalis.
  • AUGMENTATION
    • rearing and releasing of natural enemies to supplement the numbers of naturally occurring natural enemies.
    • All activities designed to INCREASE NUMBERS or effect of existing natural enemies, achieved by RELEASING ADDITIONAL NUMBERS of a natural enemy into a system or MODIFYING THE ENVIRONMENT in such a way as to promote greater number or effectiveness.

Approaches to Augmentation

  • INOCULATIVE RELEASES
    • LARGE NUMBER of individuals are released only once during the season.
    • Natural enemies are expected to reproduce and increase its population for that growing season.
    • Control is expected from the progeny and subsequent generations and not from the release itself.
  • INUNDATIVE RELEASES
    • It involves MASS MULTIPLICATION and PERIODIC RELEASE of natural enemies when pest populations approach damaging levels.
    • Natural enemies are not expected to reproduce and increase in numbers.
    • Control is achieved through the released individuals and additional releases are only made when pest populations approach damaging levels.
  • Conservation
    • actions to PRESERVE and RELEASE of natural enemies by ENVIRONMENTAL MANIPULATIONS or ALTER PRODUCTION PRACTICES to protect natural enemies that are already present in an area or NON-USE of those pest control measures that destroy natural enemies
  • Conservation involves:
    • Avoidance of harmful cultural practices.
    • Maintenance of diversity
    • Habitat manipulation practice, providing suitable habitat such as shelters, natural food, artificial food supplements to increase the population of natural enemies.
    • Protection from pesticides.

Advantages of Biological Control

  1. Absence of toxic effects.
  2. No development of resistance by the pest.
  3. No residues of poison in the soils and rivers.
  4. No build up of toxins in food chain.
  5. No killing of pollinators, or development of secondary pests through the destruction of their environment.

Disadvantages of Biological Control

  1. Control is slow.
  2. It is often unpredictable
  3. It is difficult and expensive to develop and apply
  4. It requires expert supervision.