Biotic Factors

What are pests?

Organisms that reduce agricultural productivity or the quality of the product.

Why are pests an issue in agriculture?

Natural ecosystems are replaced with simpler agroecosystems, dominated by livestock and crops.

Pests take advantage of the new community of species since there are no natural predators present

What do pests do?

• Eat the crop

• Compete for resources such as water or nutrients

• Carry pathogens

• Reduce marketability of the crop by spoiling the appearance

Why are weeds annoying?

• Competes with the crops for nutrients, light, water. Wild oats compete against cereal crops

• Harvested with the crop, reducing quality and spoiling taste

• Can be food for other pests

Why are insects annoying?

• Eat the crop

• Destroy the crop

• Reduce harvests

• Aphids suck the sap and reduce the growth of many crops (like sugarcane, fruit)

What are the 4 different types of pests?

• Endemic pests
  

• Epidemic pests

• Indigenous pests
  

• Introduced pests

Endemic pests

Pests which are always present, usually in small or moderate numbers.

Epidemic pests

Pests that are not normally present but there may be 'outbreaks' where they rapidly become a major problem.

Indigenous pests

Pests which are native to the area where they are found.

Introduced pests

Pests which have been introduced from other areas and do not have natural predators in the area.

What are pollinators?

Organisms that carry pollen from the male structure of a flower to the female structure of the same or another flower to fertilise the plant.

How to maintain pollinator populations?

• There is controlled use of pesticides (neonicotinoids) that harm bees and other pollinators

• There are introductions of bee hives to flowering crops.

How do antibiotics promote growth?

Regular small doses of antibiotics reduce the population of non pathogenic gut bacteria.

This can increase the amount of the animal's food that is used for growth, therefore increasing productivity and farm income.

Antibiotic use in disease prevention

Regular large doses of antibiotics may prevent livestock from becoming infected with pathogenic bacteria.

This may be done as a precaution, especially where the livestock stocking density is high, such as in intensive production units

Why is soil biota important?

They are important for soil fertility and crop productivity, particularly detritivores and decomposers

What do soil biota do?

They increase nutrient availability through the breakdown of dead organic matter and nitrogen fixation

What are organic acids and why are they good?

Organic acids produced by decomposition increase the weathering of rocks that releases nutrients into the soil

What do earthworms do?

Earthworms increase aeration and drainage which aid aerobic processes and water retention

What are 3 ways to control food chain energy losses?

1. Control movement

2. Control temperature

3. Raising species with lower food conversion ratios

How does controlling movement control food chain energy losses?

Reducing the movement of livestock (like keeping animals in confined spaces like barns) helps conserve their energy which can be directed to growth and food production

How does controlling temperature control food chain energy losses?

Maintaining optimal environmental conditions (e.g., heated barns in winter, shaded areas in summer) minimises energy loss due to thermoregulation. This ensures that animals use more energy for growth rather than for maintaining body temperature.

Raising species with lower food conversion ratios

Selecting species with lower FCRs (e.g. fish rather than cows) results in less energy loss and more efficient food production.