1. Chapter 8-Management options
Now a day the aim of Pest control is not eradication but reduction
of the pest population to the number that can't cause damage
1. Legal control
laws to restrict movement of pest from one area to another
The law is on the human's not on insect
Ex. Insect in North America can't come to Ethiopia by flight, but
through Planting materials and Seeds
So any person who brings material with out certification will be
punished. For this purpose law is needed
2. Quarantine is inspection of plant materials for the presence of pest
• On such phenomenon countries help each other
• But in Africa where movement of people is unchecked due to war
and other reason the problem is serious
• Newly introduced pests are damaging
• Because there is no properly designed control method for the time
being and also there is no natural enemies in the area to control
3. 2. Cultural practice - Agronomic practices that are designed to:
Optimize growing conditions for the crop.
Anything that increases a crop’s competitive edge will result in
increased tolerance to insect pests often resulting in reduced
Create unfavorable conditions for the insect pest.
• For example, when crop field is managed properly through
mowing, irrigation, aeration, and fertilization, it’s less likely to
have insect or problems.
• Change the way the crop is grown so as to
– Make crop less suitable to pests
– Make crop more suitable to biocontrols
– Make crop better withstand pest attack.
– All are preventative tactics
4. Examples of cultural control methods used independently or in
concert with other insect management tactics in IPM programs are:
Cultivation - deep ploughing and repeated cultivation brings the
larvae of Chafer grubs to the surface and they will be killed
Time of planting - crops planted at different times have different
level of infestation
• Time of planting control pests by mismatching the susceptible stage
of the plant and the damaging stage population of the pests
Ex. Maize plant in may will not be attacked by B. fusca
5. Fertilizer - using excess amount of N- fertilizer makes the
plant succulent and such plant is easy for pest attack. K-
Fertilizer is good for pest resistance
Flooding - some insect like Cotton Thrips remain in the soil
for a long period.
flood for about 2 weeks --all insects will be killed by
suffocation then drain the farm and plant your cotton
6. Sanitation – A pest cannot survive if it doesn’t have food, water
Methods to avoid introducing a pest into a field
• Cleaning field equipment
• Planting certified seed
removal of plant debris being attacked by pests from the field
Ex. Fruit fly (Ceratitis capitata) causes a problem in upper Awash.
The larvae is found in the fruit so fallen fruits have larvae unless we
remove the larvae it goes to the soil and when the adult emerged it
comes back to the plant and start damaging 6
7. Trap/Barrier Crops
– Trap crops are destroyed with the pest
– Barrier crops are on field perimeter
Intercropping - creates barrier between plants of the same
Crop rotation: Crop rotation is an excellent way to control
rootworm populations, though problems with extended
• Larvae cannot survive if a crop other than corn is planted in an
• Especially effective against root-feeding insects.
8. 2. Mechanical Methods
• Hand picking –removing insects by hand
ex. insects lays about 160 eggs per leaf and they will not transfer
to other plant until they reach third instars larvae and feed only on
the leaf where they are hatched;
therefore, hand picking of a single leaf at such stage reduces
population of pests
9. 3. Physical Methods - use of high and low temperature
– Using physical factors: use of too high or too low
temperatures, too low temperature is effective for storage
• E.g. heating of cotton seed to kill larvae of cotton bollworm
– Use of light or yellow trap to reduce pest population
10. 4. Biological control - pest control strategies that employ
biological agents to control pest.
It needs deliberate involvement of man
For this - selection of the bio agent
- monitoring are important
All these usually perform for exotic natural enemies
11. Approaches to Biological Control
a. Conservation - Manipulation of the environment to protect
and enhance the activity of existing (especially native) natural
Approaches to conservation of natural enemies involve
avoidance of practices harmful to them, as well as adoption of
practices that benefit them
– Conserving natural enemies by modifying the cropping
– Increasing vegetation diversity near or in the crop
12. b. Augmentive
• The addition of an existing predator or parasitoid into an
ecosystem to ‘help’ those already present.
Inundative release involves releasing large numbers of
natural enemies with the goal of achieving an immediate
effect on pest populations.
inoculative releases, relatively small numbers of natural
enemies are released early in the cropping season and it is
assumed that they will multiply and provide control of the
target pest later in the season.
13. Questions to ask before starting an augmentative program:
• How many beneficial will need to be released?
• When should they be released?
• Has the natural enemy been proven effective in similar
• How long will it take for control?
• What effect will other management tactics (like pesticides) have
on the natural enemy?
• Are there other practical, non-chemical alternatives?
14. C. Classical biological control
The introduction of new, exotic species of natural enemies to
control an exotic pest.
• Or Control by introducing and establishing effective natural
enemies from pest’s area of origin
15. Steps in a Classical Biocontrol Program
1. Evaluate the pest problem in the target region for the
biocontrol program. Establish taxonomic identity of
pest and area of origin.
2. Foreign exploration for the pest in the area of origin.
Surveys to assess the complex of natural enemies of
the pest, their impact and degree of specialization.
3. Selection of enemies from this complex for importation
and establishment in the target region.
4. Quarantine for removing hyperparasitoids, plant
pathogens and insect pathogens from culture
5. Release natural enemies cleared from quarantine in
the target region.
6. If agents establish, monitor change of the natural
enemy and pest population
16. Benefits of biological control
• Less hazard to the user and the environment
• minimizes chance of pest resistance
• often more economical than pesticides
• sometimes the only practical solution
• Often slower than other methods
• requires more understanding of the pest and the beneficials
• may limit control options for other pests (specific)
• Information on how to use often difficult to obtain
17. 5. Resistance - is genetical quality of the plant
• Breeders use three approaches to develop resistant cultivar
A. Antibiosis - plant produce defensive compounds
(allelochemicals) that protect them from herbivores
usually impairs/toxify an insects metabolic process – often
from secondary plant metabolites.
Non-preference(Antixenosis) - plant characteristics that lead
insects away from the host – the attractants aren’t there or
there is something that the insect does not like
- a physical or chemical property of a plant that makes the plant
unpalatable for insect attack 17
18. • Tolerance - some plant genotypes are simply "tolerate" to pest
• plants which are able to endure presence of pest with little or
no damage or no change in yield
• may be from compensatory growth, wound healing, changes
in photosynthetic partitioning
19. 6. Chemical control
is the last option in crop protection
use them when you are only forced to use them
to use it analyze the cost benefit obtained from its application
• Fast in action
• The only methods for insect approaching economic threshold
• Different mode of action choice
• they are readily available
• they are cost effective
• Toxicity to non - target organism
• Residual effect - some part of pesticide remain on plants parts
to be used as food
• pollute the ecosystem
Resurgence - rising again in to life or activity.
Insect may be destroyed but they come back after some time
because the natural enemies are killed and the natural
control is blocked
21. 8. Integrated pest management
is the use of a combination of two or more compatible pest
management tactics in a way that is
Ex. Cultural control method with Biological but not Biological with
that of Chemical control
22. The aim of IPM is
– keeping the pest population below the point at which it can't
cause economic damage by using different combination of
23. General equilibrium point - is a long term average of a pest
- is a population we encounter most of the time.
Economic or Action Threshold level
• is a pest population density at which control measure should be
taken to prevent it from reaching the Economic-injury Level (point
where economic loss occurs)
• Or the number of pests at which a decision to treat or not to treat
24. Economic Injury Level - The population density at which the cost
to control the pest equals the amount of damage it inflicts (actual
• or The number of pests at which the cost to control them equals
the amount of damage they are causing
25. You have to make decisions at
each sampling date
Maximum Tolerable Level
I Correct decision to control
II Incorrect decision to do nothing
III Correct decision to do nothing
IV Incorrect decision to control
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