R2103 1.2 Explain the importance of natural balances in plant protection

Question 1

Garden ecosystem (3)

The main actors

Answer 1

1. Producers - manufacture food from sunlight and minerals in the soil
2. Consumers - eat the plants
3. Decomposers - break down dead plant and animal material and return it to soil as minerals again

Question 2

How to help maintain biodiversity and natural balance (4)

Answer 2

1. Encourage pollinators with nectar rich plants
2. Leaving some weed (e.g. nettles) as food for caterpillars
3. Adding water for amphibians such as frogs, and for birds to drink
4. Creating over wintering sites for benefical insects

Question 3

Attracting beneficial organisms and animals

Answer 3

1. Provide shelter
2. Provide pollen and nectar for insects
3. Provide water

Question 4

Birds

Answer 4

1. Thrush - eat worms, snails and insects, in winter berries and fruit. To entice them leave food near to bushes and undergrowth
2. Blue tit - eats insects, caterpillars, seeds and nuts. Will nest in any small holes - common occupants of nest boxes

Question 5

Hedgehog

Answer 5

1. Eats beetles, caterpillars, snails, millipedes, earwigs, worms, slugs, frogs, and bird eggs
2. Makes nest of leaves, grass and other plants. Will also nest in semi-manmade structures such as a pile of logs, or a manmade wooden nest box.

Question 6

Frog

Answer 6

1. Feed upon aquatic and terrestrial invertebrates, worms and molluscs
2. Live in ponds or damp sheltered habitats

Question 7

Ladybird

Answer 7

1. Eat aphids

Question 8

Lacewing

Answer 8

1. Eat aphids and other insect pests

Question 9

Hoverfly and lavae

Answer 9

1. Hoverfly larvae eat aphids
2. Adult mimics a wasp. They are important pollinators

Question 10

Practices that disturb natural balance (3)

Think pesticides - Slug pellets / Aphid killer

Answer 10

1. Slug pellets may kill frogs and toads that were poisoned slugs
2. Chemicals that kill aphids may kill ladybirds and aphids breed faster than ladybirds
3. Growing large areas of a single type of plant - lawns are monoculture

Question 11

Physical control natural balance

Answer 11

1. Use of partial soil sterilisation may affect natural balance as good bacteria and fungal spores have been killed off - disease may spread.

Question 12

Cultural control natural balance (2)
What is beneficial?

Answer 12

1. Rotation of crops causes a beneficial change in fungal and bacterial population
2. Organic soils have more beneficial fungal and bacterial species to help maintain natural balance

Question 13

Biological control natural balance (7)
How balance is lost.

Answer 13

1. Imported plant species can introduce pests and diseases
2. Some practices can disturb the natural balance - destruction of woodland, removal of wild flowers from a garden to plant food crops or more desirable flowers.
3. removal of plants useful for beneficial insect - e.g. ‘poached egg plant’ Limnanthes douglasii which is useful for hoverflies
4. Removal of rotting hollow stems of herbaceous perennials that are home to parasitic wasps, beetles and centipedes
5. Lack of good soil structure may hinder movement of useful predators such as centipedes
6. Inattention to soil pH and nutrient levels may result in poor microbial action
7. Not use crop rotation - leading to a build up soil borne pests and diseases

Question 14

Chemical control natural balance (8)
Issue with using Chemical controls

Answer 14

1. Some weeds are important in maintaining butterfly species
2. Glyphosate is toxic to fish so take care spraying herbicides near water
3. Some herbicides are toxic to benefical insects
4. Careless spraying may kill desirable plants
5. Some herbicide vapour will damage crops e.g. tomatoes
6. Insecticides can easily kill off benefical insects such as ladybirds and parasitic wasps. Can damage biologicial controls
7. Read labels carefully! See whether active ingredient kills biological controls
8. Some evidence suggest that copper based fungicides may reduce levels of benefical fungi

Question 15

Restoring natural balances (7)
What do plants need?

Answer 15

1. Provide plants with optimal conditions of soil fertility and microclimate to reduce likelihood of fungal infections and stimulate beneficial bacteria
2. Provide plants with disease free compost and soils
3. Avoid introduction of diseased plants
4. Choose cultivars with proven track record of resistance
5. Read pesticide labels carefully - check active ingredient will not kill biological controls and active ingredient
6. Be careful spraying in greenhouse and near ponds
7. Avoid spray drift