Insecticides

Question 1

What are the 3 types of growth regulators?

Answer 1

Moulting hormone mimics
Juvenile hormone mimics
Chitin synthesis inhibitors

Question 2

What are the three groups of organochlorides?

Answer 2

DDT group
HCH group
Cyclodienes

Question 3

What is DDT?

Answer 3

Organochloride
Dichlorodiphenyltrichloroethane
First prepared in 1874, insecticidal properties discovered in 1939
Used during war
Cheap and stable molecule
Fat soluble and so biomagnifies
Leads to egg shell thinning in bird main mode of action is neurotoxin, interferes with sodium channels at axons
Contact feeding poison with no systemic activity

Question 4

Characteristics of organochlorides?

Answer 4

Extremely stable group,Mahler lives measured in years

Chemically composed of C, H and Cl groups

Question 5

Examples of pyrethroids?

Answer 5

Allenthrin
Permethrin
Deltamethrin
Cypermethrin

Question 6

What is the difference between natural and synthetic pyrethrum?

Answer 6

Synthetic is much more photostable, sites of auto oxidative attack are removed.
Synthetic chemicals are cheaper to produce
Synthetic is much more toxic and can be applied at lower rates

Question 7

How do pyrethroid insecticides work?

Answer 7

Contact and stomach poisons, no systemic activity
Interfere with sodium channels on nerve axons, like DDT
Have a rapid knock down effect suggesting that the peripheral nervous system is affected immediately

Question 8

Characteristics of organophosphate insecticides

Answer 8

Developed from sarin and tabun 
First insecticide was Schradan, now replaced
All tri-esters of phosphoric acid
Breaks down in days/weeks
Very widely used worldwide

Question 9

Examples of organophosphates?

Answer 9

Malathion
Parathion
Chlorpyrifos

Question 10

Mode of action of organophosphates?

Answer 10

Systemic
Neurotoxins - interfere with then synaptic transmission of nerve impulses
Blocks the enzyme that breaks down acetylcholine

Question 11

Characteristics of carbamate insecticides?

Answer 11

First product was carbaryl
Synthetic carbonates are lipophilic
Overall use is declining yet they are still available

Question 12

Examples of carbamates?

Answer 12

Carbaryl
Primicarb
Aldicarb

Question 13

Mode of action of carbamates?

Answer 13

Like organophosphates they block acetylcholinesterase

Process is called carbamylation

Question 14

What is administered in case of organophosphate or carbamate poisoning?

Answer 14

Atropine

Question 15

Characteristics of Neonicotinoids?

Answer 15

Newest group of synthetic insecticides
Imidacloprid was first product and was the most widely used insecticide in the world as of 2009
Based on the alkaloid nicotine

Question 16

Mode of action of Neonicotinoids?

Answer 16

Contact and systemic activity
Work as antagonists to acetylcholine
Build up of acetylcholine causes death

Question 17

What are insect growth regulators?

Answer 17

Chemicals that affect the growth and development of insects

Mostly effective against juvenile stages

Question 18

What is juvenile hormone, some examples and what it is used on?

Answer 18

Keeps insects in juvenile stage
Examples are kinoprene/methoprene
Used against fleas

Question 19

What is moulting hormone, examples of it and where it’s used?

Answer 19

Cause a moult to occur
Can be used against juvenile stages
Examples include tebufenozide and halofenozide
Used against a range of pest species

Question 20

Characteristics of chitin synthesis inhibitors?

Answer 20

Most successfully developed group of IGRs
All cause a reduction in chitin synthesis
Disrupts the enzyme chitin synthetase
Insects die from dehydration, predation etc
Very successfully used in locust control operations in Africa

Question 21

What are the 5 synthetic inscticides?

Answer 21

Organochlorides
Pyrethroids
Organophosphates
Carbamates
Neonicotinoids