This document discusses biological control of agricultural insect pests through the use of living organisms. It describes how biocontrol agents like predators, parasites, pathogens and competition from other species can be used to suppress pest populations. The document outlines different types of biocontrol including importation, augmentation and conservation. It also addresses safety concerns regarding non-target impacts and how thorough testing is required. Some advantages are specificity to pests and lack of toxic effects, though control may be slow and depend on environmental conditions. Overall, properly planned biological control can provide an effective and environmentally friendly approach to pest management in agriculture.
3. Introduction
Pest
A pest is any animal or plant which has a harmful effect on humans, their
food or their living conditions.
How damage crops?
First is direct injury by the feeding
The second type is indirect by transmits an infection into a crop.
About 25-30 % of loss in yield is due to pest.
4.
5. Cont.
Drawbacks of chemical pesticides
Are non-specific
Long lasting effect
Pesticide resistance
Health effect on human and animals
Environmental pollution
On other hand Biocontrol is safe to plants, animals, humans and the
environment.
6.
7. Cont.
What is biocontrol?
The use of living organisms to suppress the population of a specific pest
organism, making it less abundant or less damaging.
How control?
• Direct killing
• Competition
8. Agents for biocontrol
Predators
Predators are mainly free-living
species that directly consume a
lot of prey during their whole
lifetime.
e.g Ladybugs feed on aphids.
9. Cont.
Parasites
Parasitoids lay their eggs on or
in the body of an insect host,
which is then used as a food for
developing larvae. The host is
ultimately killed.
Example; wasps
10. Cont.
Pathogens
Pathogenic micro-organisms include
bacteria, fungi, and viruses.
Baculoviruses are useful in biological
pest control.
Microbial control agent that is available
commercially is the bacterium Bacillus
thuringiensis (Bt).
11. Cont.
Bt action
Bacterial spore and crystal enter the body of
host
Spore germinate and a toxin release
Toxin bind to specific receptor on gut of pest
and pest stop eating
Gut damage follow entry of bacteria to body
Pest die when bt enter their body
12. Cont.
Competition
Fight for survival,
Food, water and other factors
Species less suited to compete for
resources should either adapt or die out.
13. Types of biocontrol
Importation:
Importation involves the introduction of a pest's natural enemies to a new
locale where they do not occur naturally.
Classical biological control is long lasting
Poor adaptation to new environment.
A beetle was imported from Australia to California in the 19th century.
14. Cont.
Augmentation
Here large population of natural enemies are administered for quick pest
control
Augmentation involves the supplemental release of natural enemies,
boosting the naturally occurring population.
Fast-acting, short-term control.
15. Cont.
Conservation
Conservation of existing natural enemies.
Enhance conditions for existing natural enemy survival and reproduction.
Natural enemies are already adapted to the habitat and to the target pest,
and their conservation can be simple and cost-effective.
No need to purchase the organisms so, cost effective.
16. Safety concerns
There are two main areas of safety issues that must be considered.
First, the introduction of the biocontrol agent have adverse effects on non-
target organisms?
The second concern is the strength and duration of the biocontrol agent
on the environment.
Therefore the Biocontrol agents must be approved before they are
imported, marketed and applied.
17. Information required for safety
A clear host range assessment must be undertaken.
Understanding of the similarities between region of bioagent collection
and release.
Knowledge of dispersal mechanisms of biocontrol agent.
Potential direct or indirect effects on non-target organism.
18. Advantages
Biocontrol agents are usually very specific.
Absence of toxic effect to human or environment.
No development of resistance in pest.
Require little human effort, biological agents spread on their own.
Less expensive compare to other control methods.
19. Dis-advantages
Control is slow
Possibility that the predator will switch to a different target - they might
decide eating your crops instead of the insects.
Not complete wipe out the harmful pests but only reduce number
While it is cheap in the long run, but A lot of money goes into developing
a successful system.
Depend upon environmental conditions.
20. Cont.
A famous example of this effect is the introduction of the cane toad into
Australia in 1935.
The goal was for the toads to catch and eat the beetles that were attacking
the sugar cane crops.
Not only was this plan unsuccessful but the cane toad has now become an
invasive species.
21. Conclusions
Barrier to biocontrol is the necessity of management and planning.
For optimum benefit, the user must understand the biology of both the
target pests and their natural enemies.
The risks associated with biocontrol to human/animal health are very low.
Agents main use crop as food source.
There is no example of significant damage.