chemical and biological control of agricultural pests

Question 1

pests

Answer 1

competing organisms within the food web that compete for energy within our (human) food chain and space

Question 2

pesticides

Answer 2

poisonous chemicals that kill pests

Question 3

herbicides

Answer 3

poisonous chemicals that kill plants

Question 4

insecticides

Answer 4

poisonous chemicals that kill insects

Question 5

fungicides

Answer 5

poisonous chemicals that kill fungi

Question 6

what makes a pesticide effective?

Answer 6

1) being specific
2) biodegradable
3) cost effective
4) not accumulate

Question 7

why should the pesticide be specific

Answer 7

it should have a direct effect on the targeted pest only, it should be non-toxic to humans, natural predators of the pests and organisms that contribute to the growth of crops e.g. bees and earthworms

Question 8

why should the pesticide be biodegradable

Answer 8

• once applied it should be broken down into harmless substances in the soil - so they do not accumulate around crops
• chemically stable to have a long shelf life

Question 9

why should the pesticide be cost effective

Answer 9

• pests can develop genetic resistance towards certain pesticides meaning there will be costs associated in development of new pesticides that may be temporary; growers must be able to afford them in order to increase productivity

Question 10

why should the pesticide not accumulate

Answer 10

so it does not build up - either on specific parts of organisms and crop, or get passed along the food chain

Question 11

biological control

Answer 11

• aims to control pests and not eradicate them

- this can be done by using organisms that are either predators or parasites of the pest organism

Question 12

how to make biological pests effective

Answer 12

• the control agent and the pests should exist in balance with one another, at level where the pest has little to no adverse effect
  e. g. if predators manage to eat and reduce amount of pests, this means there would insufficient food for the predator meaning they would compete and die of hunger, allowing the pest organisms to multiply unchecked

Question 13

advantages of using biological control for pests

Answer 13

• very specific
• there will be no genetic resistance involved
• once introduced, control agent can reproduce itself naturally, so reintroduction is not needed

Question 14

disadvantages of using biological control for pests

Answer 14

• control agent may become pest if there is lack of pests to feed on, so they may resort to feeding on crops
• they do not act as quickly, there will be a time interval between introducing the control agent and reduction of pests

Question 15

advantages using chemical pesticides for pests

Answer 15

• effect acts on pesticides quickly

- readily available

Question 16

disadvantages using chemical pesticides for pests

Answer 16

• will affect non-target species that contribute to growth of crops (e.g. bees and earthworm)
• pests may develop genetic resistance, eliminating the effect of the pesticide, therefore increasing the costs associated with buying new effective pesticides

Question 17

integrated pest-control systems

Answer 17

• systems that aim to integrate all forms of pest control rather than relying on one type
• emphasis on the acceptable level of pests, rather than trying to eradicate them all

Question 18

disadvantages of eradication

Answer 18

• counterproductive
• costly
• nearly impossible to achieve

Question 19

what does IPCS involve

Answer 19

1) removing the pest mechanically (vacuuming, hand picking, erecting barriers)
2) choosing animals and plants that suit the local area and are pest resistant
3) providing suitable environment for natural predators in order to keep them away from ever having the need to eat the crops
4) regular monitoring of crops
5) using biological agents

Question 20

what should a grower do if all methods of IPCS do not work

Answer 20

• they can resort to using chemical pesticides if level of pests becomes uncontrollable

Question 21

advantages of IPCS

Answer 21

• effective
• minimum impact on the environment
• reduce disruption of food webs

Question 22

effect of pests

Answer 22

• reduce productivity in agricultural ecosystems
• damage leaves of crops
• compete with humans and animals by eating the crop itself

Question 23

how do pests affect productivity

Answer 23

1) they compete with crop plants for space, CO2, water, nutrients and light
- creates limiting factors for photosynthesis, therefore the rate of photosynthesis decreases
- less energy available in stores for respiration and growth
- productivity decreases
2) damaging leaves
- plants cannot carry out photosynthesis
- they die off
- productivity decreases

Question 24

monoculture

Answer 24

the agricultural practice of producing or growing a single crop, plant, or livestock species in a field or farming system at a time

Question 25

how do pests affect monoculture

Answer 25

- fungal and insect pests can spread rapidly - for animals, pests that cause disease allow the disease to spread within the monoculture, making a lot of animals unfit for consumption or causes their death - reduce productivity

Question 26

what is the aim of pest control

Answer 26

- economically, to balance cost of pest control with the benefits it brings

Question 27

two interests associated with pest control

Answer 27

1) farmer that has to meet demand of consumers for cheap food whilst also making a living out of it 2) ethical issues involved with conservation of natural resources in order to allow us to grow more crops and produce more food