This document discusses the use of chemical and biological control of pests. It defines pests, pesticides, chemical control, and biological control. Chemical control involves using pesticides like insecticides, herbicides, and fungicides, while biological control uses living organisms like predators, parasitoids, and pathogens. Both methods have advantages and disadvantages. Chemical control is fast but can accumulate and harm other organisms. Biological control is more targeted but takes longer. Pests can develop resistance to chemicals over time. The document also compares the differences between the two methods and discusses the effects of pesticides on the environment.

1. THE USE OF CHEMICAL AND
BIOLOGICAL CONTROL OF PESTS

2. DEFINITIONS
 Pests - Organisms that compete with humans for
food sources and space. They can be plants,
animals or other organisms.
 Pesticide – Substances or mixtures of substances
that can destroy or lessen the severity of any pests.
 Chemical Control of pests – refers to the
management of pests that involves applying
synthetic or naturally derived pesticides .
 Biological Control of pests – refers to the use of
living organisms to control various pests

3. MANAGEMENT OF PESTS
 Controlling pests is important in the agricultural
industry. If not treated properly pests will invade our
crops, damaging human food sources.
 There are two main ways to manage pests:
1. Chemical control
2. Biological control

4. CHEMICAL CONTROL
 As mentioned before, Chemical Control involves the use of pesticides
 Types of Pesticide:
Types of
Pesticide:
Effect on Pest
Insecticide Kills insects through various means. E.g.
damaging the nervous system
Herbicide Kills plants
(i) non- selective Destroys all plants that come in contact with the
herbicide
(ii) selective Only destroys specific types of plants, leaving
other plants unharmed
Fungicides Control fungal diseases on plants

5. ADVANTAGES AND DISADVANTAGES OF
CHEMICAL CONTROL
ADVANTAGES DISADVANTAGES
Fast acting Accumulates in the environment
Able to control large infestations Kills beneficial organisms
Easy to obtain and apply Creates health problems to
humans
Effective in increasing crop
production
Easily spreadable by wind,
affecting other organisms
Contaminates groundwater, when
repeated use
Pests can develop genetic
resistance to pesticides overtime.

6. BIOLOGICAL CONTROL
 As mentioned before, biological control of pests
refers to the use of living organisms to control
various pests
 There are three categories of natural enemies to
pests
I. Predators – refers to living organisms which feed
on pests
II. Parasitoids - insects with an immature stage that
develops on or inside an insect host
III. Pathogens – fungi or bacteria
E.g. Pest- coffee berry borer. Bio control agent – ants
(predators)

7. ADVANTAGES AND DISADVANTAGES OF
BIOLOGICAL CONTROL
ADVANTAGES DISADVANTAGES
If successful, does not have to be
reapplied
Takes longer to effect control
Increases diversity within the
ecosystem- leads to stability
May upset ecological balance
when introduces – the organism
itself may become a pest, or harm
beneficial species

8. DIFFERENCES BETWEEN CHEMICAL AND
BIOLOGICAL CONTROL
BIOLOGICAL CONTROL CHEMICAL CONTROL
Very specific, chosen predator
would only eat the pest.
Can have some effect on other
non-targeted organisms.
Pests does not become
resistance.
Pests can develop genetic
resistance to pesticides overtime.
Control organism; reproduces itself
once it has been introduced
therefore cheaper.
Reapplied at intervals , therefore
expensive
No pollution Toxic to humans
Farmers have to be educated
about the biology of pests and
their natural enemies.
Toxic chemicals accumulates in
organisms and are passed down
the food chain.

9. EFFECTS OF PESTICIDE ON THE
ENVIRONMENT
 Some effects of pesticide are:
I. Pesticides damage ecosystems
II. Pesticides may damage or harm un-targeted
animals
III. Pesticides decrease biodiversity
IV. Pesticides may cause a decline in populations or
even cause extinction of species
V. Pesticides disrupts food chains/webs - the natural
balance in ecosystems