Lecture 2

Question 1

How many described insect species?

Answer 1

1 million

Question 2

How many insects are pests?

Answer 2

9000 insects and mites

Question 3

How many different species of weeds?

Answer 3

8000

Question 4

How many different plant pathogens?

Answer 4

50,000

Question 5

What is a pest?

Answer 5

-Anthropogenic term, loose
- Insects become pests when they interact with human welfare, aesthetics or profits (physical, medical, economic)
-No particular ecological significance

Question 6

What is a parasite?

Answer 6

• Lives on or inside another organism, the host, causing it some harm
  -Reduces animal health
  -Younger animals often more susceptible

Question 7

What percentage of wheat is lost globally?

Answer 7

21.5%

Question 8

What percentage of rice is lost globally?

Answer 8

30%

Question 9

What percentage of maize is lost globally?

Answer 9

22.5%

Question 10

Insects as pests

Answer 10

-Herbivores
-Transmit disease
-Allergic reactions

Question 11

Why do invertebrates become pests?

Answer 11

-Accidental introduction to areas outside native range
-Become a vector of disease
-Move from native plants to introduced ones eg. crops
-Simplified monoculture ecosystems
-Other farming and cultivation practices

Question 12

Why o invertebrates become pests in simplified monocultural ecosystems?

Answer 12

-Dense aggregations of food resources = proliferation of certain generalist and specialist pests
-Less natural enemies

Question 13

Why do invertebrates become pests in other farming and cultivation practices?

Answer 13

-Continuous cultivation without fallow = build up of pests
-Prolonged insecticide use = less natural enemies, insecticide resistance

Question 14

Types of pest control?

Answer 14

-Cultural
-Mechanical/Physical
-Biological Control
-Chemical Control

Question 15

History of Pest Control

Answer 15

1. Cultural Control (manipulation of husbandry practice- ‘pre-historic’)
2. Mechanical/Physical Control (exclusion /removal /destruction - ‘Pre-historic’)
3. Biological Control (deliberate manipulation of ‘natural enemies’)
4. Resistant Crops (use of inherited genetic resistance)
5. Chemical Control

Question 16

Chemical Insecticides

Answer 16

-Deceloped during and after 2nd world war
-Initially effective and cheap
-Replaced traditional forms of chemical, cultural and biological control
-Insecticide “boom”

Question 17

Why is an increase in pesticide use not effective?

Answer 17

-Despite increased insecticide use, damage by insect pests has increased dramatically
-Eg. prop crops damaged by pests doubled 7-13% from 1950 to 1985 in the US

Question 18

Imbalances between pest problems and control?

Answer 18

-Human trade and movement of pests
-High yield varieties more susceptible to pests
-Monocultures with reduction in sanitation and rotation
-Aggressive commercial marketing

Question 19

Limitations on the use of pesticides?

Answer 19

1. Target resistance (in insects, plant pathogens and weed species)
2. Target Resurgence (pest returning after beneficial natural enemies killed)
   3.Residues (in food crops)
   4.Induction of Secondary Pest Problems (former non-pest species that were controlled by natural enemies)
3. Environmental contamination (affecting wildlife and pollinators as natural enemies)
   6.Chronic Occupational Exposure/ Human Health

Question 20

What is Insecticide resistance?

Answer 20

-Selection of individuals predisposed to survive insecticide
-Cross resistance
-Multiple resistance

Question 21

Why move towards less insecticide use?

Answer 21

-Problems with insecticide resistance
-Cost of insecticides
-Strong consumer backlash against environmental and human heath concerns (non-target organisms)
-Development of alternative controls

Question 22

Integrated Pest Management

Answer 22

-First promoted in 1960’s following failure of insecticides in cotton
-Philosophy is to limit economic damage and simultaneously minimise
>Adverse effects on non-target organisms
>Adverse effects on consumers
>Adverse effects on environment
-Ecologically based. Combines:
>Physical control
>Cultural control
>Biological and chemical control
>Use of resistant varieties