It provides a brief knowledge about Biological control & its strategies

1. Syed Muhammad Ali Zahid
Department of Entomology
University College of Agriculture
University of Sargodha

2. What is Biological Control?
• “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”
OR
• The précised use of “natural enemies”
to maintain phytophagous pest populations
within acceptable limits

3. History
• Term “Biological control" was first used in
(1919) by “Harry Scott Smith”
in meeting of American Association of
Economic Entomologists, California
• The first reported by Chinese botanist Ji Han
(263-307),in his book, (ca. 304 AD)
Nan Fang Cao Mu Zhuang” (Plants of the
Southern Regions)
• He mentioned that “Jiaozhi people used &
sell reddish-yellow ants and their nests, to
control citrus insect pests
C. name: Huang Gan
T. name: Oecophylla smaragdina

4. Evolution in Biological control
• In the end of nineteenth century,
Californian citrus orchards had suffered
attacks from the Australian scale, Icerya
purchasi.
• This scale was successfully controlled with
the introduction of its natural enemy, the
coccinellid Rodolia cardinalis.

5. Conti….
• In Russia at around the same time,
the fungus Metarhizium
anisopliae was used for the
control of Anisoplia austriaca, a
cereal beetle parasite.

6. Types of Bio-control agents
Entomophagous insects:
• These are the main agents used
in biological control
Two types:
1. Predators
2. Parasitoids

7. Predators
• Organism that captures and eats another organism
(the prey)
• usually larger than their prey
• Death of the prey is usually immediately after capture
• Specialist predators, live on one or on a small number of species.
• General (polyphagous), which can live on several species.
• The polyphagous species are considered less suitable than monophagous
species, because they are less likely to concentrate feeding on pest species
in the presence of an abundant alternative

8. Examples

9. Parasitoids
• 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

10. Examples

12. Pathogenic microbial agents
• Includes:
Bacteria, Viruses, Fungi, Protozoa,
Nematodes
Entomophagous nematodes:
• Obligate parasite
• Visible to naked eye
• About 0.5 mm in length

13. • 2 families:
Steinernematids
Heterorhabditids
• Inserts symbiotic bacterias
through cuticle
• Within 48 hours, death occurs by
septicemia (blood poisoning)

14. Entomopathogenic fungi
• About 750 species of
fungi that cause
infections in insects
• Fungi produce spores
which infect their host by
germinating on its
surface and then growing
into its body
• Death takes between 4
to 10 days, depending on
the type of fungus and
the number of infecting
spores
Beauveria bassiana

15. Baculoviruses
• 1600 viruses have been
recorded from more than
1100 species of insects
3 families:
• Baculoviridae,
Polydnaviridae,
Ascoviridae
• Viruses enters through body
receptors in the gut and
penetrate in epithelial cells
• Acute infections lead to host
death in 5 – 14 days.

16. Bacteria
• Families:
Bacillaceae, Pseudomonadaceae, Enterobacteriaceae, Streptococcaceae, and
Micrococcaceae
• Most of the bacteria are weak pathogens but a minority are highly virulent
• Bacillus popillae causes milky disease in scarbaeids
• Bacillus sphaericusis a lethal pathogen of mosquitoes
• Bacillus thuringiensis (Bt) is wide spread in soil,is a lethal pathogen of a
range of orders, specially against cotton bollworms

17. Strategies
1. Introduction / Importation
• Introduction of pest's natural enemies
to a new locale where they do not occur naturally
• Involves travelling to the pest species' country of origin, researching it’s
natural enemies, collecting and introducing these natural enemies to the
location where the pest species is causing problems
• E.g. In Australia, Eriosoma lanigerum was controlled by the introduction
of its specific parasitoid Aphelinus mali

18. 2. Augmentation control
• Augmentation is trying to increase the natural enemies of the pest
species
• Used in situations where natural enemies population levels are too low
to be effective, so numbers are augmented by the use of laboratory-
cultured natural enemies.
• Method relies upon continuous human management and unlike the
importation and conservation approaches, is not a permanent control

19. 3. Conservation
• Prevention of existing natural enemies in an environment is the third m
ethod of biological pest control.
• Involves identifying any factors that limit the effectiveness of the
natural enemies of the pest and changing these limiting factors to help
the beneficial species
• E.g. when nectar producing crop
plants are grown in the borders of rice fields.
These provide nectar to support parasitoids and predators of plant
hopper pests and have been demonstrated to be so effective.

20. References
1. Flint, Maria Louise & Dreistadt, Steve H. (1998). Clark, Jack K., ed. Natural Enemies Handbook: The Illustrated
Guide to Biological Pest Control. University of California Press. ISBN 9780520218017.
2. Biological Control: Harry Smith Fund (http://biocontrol.ucr.edu/hoddle/harrysmithfund.html)
3. DeBach P., Hagen K. S., 1964. Manipulation of entomophagous species , p. 429458. In: P. DeBach (Ed.), Biological
control of insect pests and weeds. Reinhold, New York, 844 pp.
4. http://httpserver.carleton.ca/~bgordon/Rice/papers/peng83.htm
5. Coulson J. R., Vail P. V., Dix M. E., Nordlund D. A., Kauffman W. C., Eds. 2000. 110 years of biological control
research and development in the United States Department of Agriculture: 18831993. U.S. Department of
Agriculture, Agricultural research Service 645 pp.
6. McLeod J. H., McGugan B. M., Coppel H. C., 1962. A Review of the Biological Control Attempts Against Insects
and Weeds in Canada. Technical Communication No. 2. Commonwealth Agricultural Bureau. Reading: England, 216
pp.
7. "What is Biological Control?". Cornell University. Retrieved 7 June 2016.
8. "Classical Biological Control: Importation of New Natural Enemies". University of Wisconsin. Retrieved 7 June
2016.

21. Questions