Human impact on the environment
In this lesson you will learn about:
• the biological control of pest species
• the use of GM crops as an alternative to using
fertilisers and pesticides
Success criteria
Explain biological control of pest species works
Explain how GM crops can be used as an alternative
to fertilisers and pesticides
Human impact on the environment
The biological control of pest species
• Can you name any common pest species that
damage plants?
(aphids, scale insects)
(rabbits, rats)
• Can you think of how these can be controlled
without using chemicals?
Human impact on the environment
Biological control of pest species is when the pest
species numbers are controlled without the use of
chemicals.
Instead a biological control method is used.
Rabbits can become a problem for
Landowners if numbers multiply
too much.
Why do you think this is?
A solution is to introduce the
virus myxomatosis which infects
and kills many of the rabbits
Human impact on the environment
The biological control of plant pest species includes:
• Ladybirds to kill aphids and scale insects
• Caterpillar moths to kill cacti
Why use these method instead of chemicals?
Human impact on the environment
The alternative is to use pesticides against the
insects and plants.
These chemicals can be harmful to non-pest
species directly and in run-off into fresh water.
Human impact on the environment
GM crops can be used as an alternative to using
fertilisers and pesticides.
You have studied GM crops in a previous topic.
How can GM crops be used instead of these
chemicals?
Human impact on the environment
Drought resistance can be
transferred to the GM crop
which will give better
growth in dry conditions
Pest resistance will give
enhanced yields for crops
that might otherwise show
a lesser yield
Human impact on the environment
Other GM crops include:
Alfalfa (Medicago sativa)
Argentine Canola (Brassica napus)
Bean (Phaseolus vulgaris)
Carnation (Dianthus caryophyllus)
Chicory (Cichorium intybus)
Cotton (Gossypium hirsutum L.)
Creeping Bentgrass (Agrostis stolonifera)
Eggplant (Solanum melongena)
Flax (Linum usitatissumum L.)
Maize (Zea mays L.)
Melon (Cucumis melo)
Papaya (Carica papaya)
Petunia (Petunia hybrida)
Plum (Prunus domestica
Polish canola (Brassica rapa)
Poplar (Populus sp.)
Potato (Solanum tuberosum L.)
Rice (Oryza sativa L.)
Rose (Rosa hybrida)
Soybean (Glycine max L.)
Squash (Cucurbita pepo)
Sugar Beet (Beta vulgaris)
Sugarcane (Saccharum sp)
Sweet pepper (Capsicum annuum)
Tobacco (Nicotiana tabacum L.)
Tomato (Lycopersicon esculentum)
Wheat (Triticum aestivum
You could research one of them, and share with class
if time allows
Human impact on the environment
There are a lot of
GM crops and the
science is
relatively new.
There are differences of opinion about GM
crops and there benefits.
But remember to look at the science.
Human impact on the environment