biotic factors and their control

Question 1

list the biotic factors which affect agriculture

Answer 1

1) pests
2) pollinators
3) soil biota

Question 2

define pest

Answer 2

organisms which reduce agricultural productivity or the quality of a product eg eating the crop, competing for resources, pathogens, spoiling the appearance and reducing ability to sell

Question 3

outline the difference between endemic and epidemic pests

Answer 3

endemic- pests which are always present usually in small or moderate numbers

epidemic- pests which are not normally present but there may be outbreaks where they become a major issue

Question 4

outline the difference between indigenous and introduced pests

Answer 4

1) species which are native to the area they are found

2) pests which are found in an area they are not supposed to be

Question 5

what is cultural pest control

Answer 5

the use of non-pesticide methods to reduce the risk of pest damage often by using natural ecosystem services

Question 6

list the different types of cultural pest control

Answer 6

1) crop rotation
2) companion crops
3) predator habitats
4) biological control
5) sterile males
6) pheromone traps
7) genetic resistance to disease
8) GM crops

Question 7

outline crop rotation

Answer 7

1) different crops often have their own unique pests
2) if the same crop is grown throughout the year it allows the survival of the pests for future years
3) crop rotation involves the cultivation of different crops each year so the remaining pests at the end of one year will have died off before the crop is grown again

Question 8

outline companion crops

Answer 8

1) crops, which when grown together, will be more productive
2) in some cases one is only grown to increase the harvest of another eg it masks the smell of the market crop so pests attack that instead

Question 9

outline predator habitats

Answer 9

increases the populations of natural predators by providing suitable habitats such as bottle banks, these predators then control pest populations

Question 10

outline biological control

Answer 10

predator or pathogen species may be introduced to control pests, they should be specialist feeders that will only eat the pests, if they had a wider diet they may eat beneficially non-target species

Question 11

outline sterile male techniques

Answer 11

1) in many insects females only mate since
2) if a female mate with a sterile male she will never produce offspring
3) males are exposed to gamma radiation and then released
4) death rate would exceed birth rate and populations would decline

Question 12

outline pheromone traps

Answer 12

1) in many insects, mates are attracted by scents
2) pheromone traps mimic the scent that attracts the pests and they become stuck on a sticky surface
3) this allows proof of the presence of a pest so other techniques can be introduced or it can be used to kill enough of one gender so not enough breeding pairs

Question 13

outline the properties of chemical pesticides

Answer 13

1) toxicity = high toxicities require smaller vomules
2) specificity = the measure of the range of taxa affected
3) persistance = how long it lasts after application
4) soluability = if it is water-soluble it is likely to be washed off, therefore, needs reapplication
5) mode of action=
- contact actions- sprayed onto the plant-killing insects which come in contact with it
- systemic actions- absorbed by the crop and translocated throughout

Question 14

why are antibiotics used

Answer 14

1) treat infections
2) prevent infections
3) to promote growth

Question 15

what is integrated control

Answer 15

the use of a combination of pest control methods to maximize pest control whilst minimizing environmental impacts

Question 16

what are the principles of integrated control

Answer 16

1) use of cultural techniques which make growth environment less suitable for pests
2) use of cultural techniques that prevent the build-up of the pest populations
3) cultivating species and varieties that are less likely to suffer an attack
4) use of pesticides only when essential

Question 17

how can pollinators be aided

Answer 17

1) provision of food supplies by growing plants that provide nectar
2) restricting the use of pesticides that harm polinators
3) introduction of beehives