- Plants and animals depend on each other for their survival. This relationship is called interdependence.
- Plants depend on other plants as well as on animals.
- Animals depend on other animals and also on plants.
Types of interdependence can be grouped into:

• Plant to plant interdependence.
• Plant to animal interdependence.
• Animal to animal interdependence.
• Animal to plant interdependence.

Plants depend on other plants for shade, support, habitat and also nutrients.

• Plants depend on animals for pollination, dispersal and nutrients. For instance insectivorous plants trap and digest insects to obtain nitrates.
• When animals produce faeces or die and decompose, plants obtain manure.
• Animals depend on other animals for food. Herbivores (preys) are eaten by carnivores (predators.)
• Animals depend on plants for food, shade, medicines, habitats and oxygen.

- A food chain is a feeding relationship between organisms.
- Animals depend on plants directly for food.
- Carnivores are animals that depend on other animals for food.
- Omnivores are animals that depend on both plants and animals for food.
- An example of a food chain is given below.
Plants Zebra Lion Vulture
Note:

• The arrow points to the eater.
• Plants are called producers.
• Herbivores are called primary consumers.
• Carnivores are called secondary consumers.
• Scavengers are tertiary consumers.
• Bacteria and fungi act on plant and animal remains decomposing them. They are thus referred to as decomposers.

- A crop pest is an organism that causes damage to crops.
- There are two major categories of crop pests. These are:

• Field pests
• Storage pests

(i) Field pests

• These are pests that attack and destroy crops that are growing in the field.
• These pests may destroy seedlings, growing plants or plants that are about to be harvested.
• Examples of field pests include birds, moles, aphids, cutworms, stock-borers and rodents.

• Cutworms attack the roots of seedlings just above the soil. Birds feed mostly on grains of maturing plants.
• Aphids bore plant leaves while stock-borers pierce and suck juice from plant stems.
• Moles and rodents mainly gnaw roots of tuberous crops such as sweet potatoes and cassava.

(ii) Storage pests

• These are pests that attack harvested crops stored in granaries and stores.
• They include weevils and rodents.
• Weevils bore into grains eating their content. Such grains are of poor quality and do not germinate while planted.
• Rodents feed on stored grains and tubers.

• Crop pests affect the quality of crops, their quantity and may also spread crop diseases.
• Crop pests can be controlled by trapping, scaring them, pruning, using chemicals, weeding or use of their natural predators.