Insecticides Flashcards
What are the 3 types of growth regulators?
Moulting hormone mimics
Juvenile hormone mimics
Chitin synthesis inhibitors
What are the three groups of organochlorides?
DDT group
HCH group
Cyclodienes
What is DDT?
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
Characteristics of organochlorides?
Extremely stable group,Mahler lives measured in years
Chemically composed of C, H and Cl groups
Examples of pyrethroids?
Allenthrin
Permethrin
Deltamethrin
Cypermethrin
What is the difference between natural and synthetic pyrethrum?
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
How do pyrethroid insecticides work?
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
Characteristics of organophosphate insecticides
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
Examples of organophosphates?
Malathion
Parathion
Chlorpyrifos
Mode of action of organophosphates?
Systemic
Neurotoxins - interfere with then synaptic transmission of nerve impulses
Blocks the enzyme that breaks down acetylcholine
Characteristics of carbamate insecticides?
First product was carbaryl
Synthetic carbonates are lipophilic
Overall use is declining yet they are still available
Examples of carbamates?
Carbaryl
Primicarb
Aldicarb
Mode of action of carbamates?
Like organophosphates they block acetylcholinesterase
Process is called carbamylation
What is administered in case of organophosphate or carbamate poisoning?
Atropine
Characteristics of Neonicotinoids?
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
Mode of action of Neonicotinoids?
Contact and systemic activity
Work as antagonists to acetylcholine
Build up of acetylcholine causes death
What are insect growth regulators?
Chemicals that affect the growth and development of insects
Mostly effective against juvenile stages
What is juvenile hormone, some examples and what it is used on?
Keeps insects in juvenile stage
Examples are kinoprene/methoprene
Used against fleas
What is moulting hormone, examples of it and where it’s used?
Cause a moult to occur
Can be used against juvenile stages
Examples include tebufenozide and halofenozide
Used against a range of pest species
Characteristics of chitin synthesis inhibitors?
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
What are the 5 synthetic inscticides?
Organochlorides Pyrethroids Organophosphates Carbamates Neonicotinoids
