pesticides: types and modes of action eny 3225 or eny 5226

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Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

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Page 1: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Pesticides: Types and Modes of Action

ENY 3225or

ENY 5226

Page 2: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Learning Objectives

• Learn and internalize definitions• Be able to list the steps for each

mode of action for the pesticide groups presented

• Familiarize yourself with the various products and which class of insecticide they belong to

Page 3: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Insecticide

• Any substance or mixture of substances intended for preventing, destroying, repelling, or mitigating insects.

Often associated with skin irritation

Page 4: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Vocabulary• Acetylcholine (ACh). An acetic acid ester of

choline-a substance that functions as a neurotransmitter.

• Acetylcholinesterase. An enzyme in the membrane of postsynaptic cells that catalyzes the conversion of ACh into choline and acetic acid. This enzymatic reaction inactivates the neurotransmitter.

• Cholinergic. Denoting nerve endings that liberate acetylcholine as a neurotransmitter, such as those of the parasympathetic system.

• http://www.mhhe.com/biosci/abio/glossary.mhtml

Page 5: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Vocabulary

• GABA Gamma-aminobutyric acid; believed to function as an inhibitory neurotransmitter in the central nervous system.

• GABA agonist. Chemical that binds to and activates GABA receptors

• GABAergic.• GABA Antagonists: chemicals that bind to but do not

activate GAMMA-AMINOBUTYRIC ACID receptors, thereby blocking the actions of endogenous GAMMA-AMINOBUTYRIC ACID or GAMMA-AMINOBUTYRIC ACID agonists.

• Suffix “-ergic” is used to describe the type of neurotransmitter a neuron releases

Page 6: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Vocabulary

• Enzyme. A protein catalyst that increases the rate of specific chemical reactions.

Page 7: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Types of Pesticides

• Insecticide -- kills insects• Herbicide -- kills weeds• Fungicide -- kills fungi• Nematicide -- kills nematodes• Rodenticide -- kills rodents• Pisicide -- kills fish

Page 8: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Other pesticide terms• Ovicide -- kills eggs• Larvicide -- kills larvae• Adulticide -- kill adults• Insect growth regulator -- disrupts normal growth and

development of insects• Dessicants -- cause insect death by dehydration• Repellents -- repel insects and other arthropods• Attractants -- attract insects and vertebrates• Synergists -- chemicals used to enhance the

insecticidal activity of other chemicals– piperonyl butoxide– MGK 264

Page 9: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Pesticide terms for route of entry

• Stomach poison -- enter orally usually in a food material– Insect baits -- composed of attractive food

and a toxicant– Dusts -- applied to surfaces pests contact,

pest crawls through residue, grooming results in ingestion

– Liquid baits -- boric acid and some rodenticides are water soluble and can be put in water sources of pests

Page 10: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Pesticide terms for route of entry

• Contact poisons -- enter through cuticle of insects– most pesticides are contact poisons– most are lipophilic and enter the insect

through the cuticular waxes and oils

• Fumigants -- vapors enter the insect through the spiracles during respiration– are true gases at room temperature– methyl bromide, sulfuryl fluoride,

paradichlorobenzene, napthalene are true fumigants

Page 11: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Insecticides in UPM

• Inorganics– Ex. Bora-Care, Disodium Octaborate

Tetrahydrate

• Botanicals– Ex. Pyrethrum

• Synthetic Organics– Ex. Pyrethroids

• “Natural”– Ex. Avermectins

Page 12: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Modes of Action of Insecticides

Nervous System Energy Production

Cuticle Production

Water Balance

Endocrine System

Page 13: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Nervous System

• Lethal spasms and seizures• Insects flip on back• Legs wiggle uncontrollably

Page 14: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Insecticides that Affect the Nervous System

Nervous System

permethrindeltamethrin

PyrethroidsDDT

Sodium Channel

Page 15: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Pyrethrins and Pyrethroids

• Pyrethrum -- dust derived from ground chrysanthemum flowers

• Pyrethrins -- chemicals within pyrethrum that have insecticidal properties

Page 16: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Pyrethrins and Pyrethroids

• Type I – Short residual,– Fast flushing, and– Quick knockdown,– Negative temperature

correlation: more effective at low temps

– Ex.: Allethrin, d-phenothrin, resemethrin

• Type II– Long residual,– Slower flushing, and– Slower knockdown,– Better killing power

than type 1– Positive temperature

correlation– Ex.: Permethrin,

cypermethrin, cyfluthrin, lambdacyhalothrin

Pyrethroids -- synthetically produced chemicals with similar chemistry and mode of action as pyrethrins, axonic poisons

•Synergists -- used to deactivate mixed function oxidases (MFOs) within insects

Page 17: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Pyrethroids

Permethrin

Bifenthrin Deltamethrin

Page 18: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Talstar PL Granular: bifenthrin• Unique sand core granular

• Provides a 2 to 4 month residual, supplying effective, long-term protection.

• Penetrates mulch and grass, with no watering needed.

• No odor • Low application rates

Page 19: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Pyrethroids Effects

• Action on Human System - Irritant

• Systemic Effects - Minimal

• Irritation Effects - Stinging, burning, itching, tingling, numbness of skin.

Page 20: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

MOA: Pyrethroids• Axonic poisons• Bind to a protein called the voltage-gated

sodium channel• Normally, the sodium channel opens, causing

stimulation of the nerve and closes to end the nerve signal

• Pyrethroids find to the socium channel and prevent it from closing normally

• Result: continuous nerve stimulation• Symptoms: Tremors, uncoordinated

movement

From Valles and Koehler. 1998. Insecticides Used in the Urban Environment: Mode of Action. ENY-282

Page 21: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Nerves and Pyrethroids

Sodium Channels

Direction of Nerve Impulse Repeated nerve firing

Page 22: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Nervous System

• Why does this happen?• Let’s look at a “normal” nerve

impulse.

Page 23: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

“Diagram of a neuron illustrating the subcellular locations of voltage-gated sodium channels.”

#4. Myelinated#4. Myelinated

#3. Unmyelinated#3. Unmyelinated

#6. Apical dendrites#6. Apical dendrites

#5. Presynaptic#5. Presynaptic#7. Postsynaptic#7. Postsynaptic

U of ColoradoHealth Science

Page 24: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Rensselar Polytechnic Institute

Axon Membrane at Rest

1. “Leaky membrane”K+: many leaky

channelsNa-: few leaky

channels2. Outside: >Na-3. Inside: > K+

Page 25: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Axon Membrane

Rensselar Polytechnic Institute

1. An action potential is initiated whenever there is a stimulus.

2. A stimulus is an event that causes depolarization or decrease in the membrane potential

Page 26: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Axon Membrane

1. Opening of external Na gates

2. Results in influx of Na

Page 27: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Axon Membrane1. Eventually reach

Na equilibrium

Page 28: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Axon Membrane1. As a result of the

depolarization, the internal Na+ gates shut and remain closed for about ½ millisecond.

2. The rapid decrease causes the membrane potential to return to the K equilibrium potential.

Page 29: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Pyrethroid Kill• Fast action -- 30 minutes to kill• Excessive nerve firing --spasms

Page 30: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Pyrethrins and Pyrethroid Labels

• Demon WP• Demand CS• Talstar G• Dragnet• Deltadust

Page 31: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Acetyl-cholinesterase

Insecticides that Affect the

Nervous System Nervous System

propoxurcarbaryl

permethrindeltamethrin

PyrethroidsDDT

Sodium Channel

CarbamatesPhosphates

chlorpyrifosmalathiondiazinon

Page 32: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

MOA: Carbamates and OPs

• Synaptic poisons• Carbamates and organophosphorus

insecticides bind to an enzyme called acetylcholinesterase (AChE)

• AChE is found at the nerve synapse• AChE is designed to stop a nerve

impulse after it has crossed the synapse

From Valles and Koehler. 1998. Insecticides Used in the Urban Environment: Mode of Action. ENY-282

Page 33: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

MOA: Carbamates and OPs

• OPs and carbamates bind to AChE• This prevents AChE from working

(i.e., breaking down Ach)• Therefore, nerve impulses continue

to fire across the synapse• Symptoms similar to pyrethroid

poisoning—tremors and uncontrolled movement

From Valles and Koehler. 1998. Insecticides Used in the Urban Environment: Mode of Action. ENY-282

Page 34: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Cholinesterase Inhibitors

• Organophosphates• Carbamates

Causes repeated nerve firing

Page 35: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Acetylcholine SystemAcetylcholine System

Page 36: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Organophosphate Effects• Action on Human System - Inhibits

acetylcholinesterase enzyme in tissues.• Systemic Effects - Headache, dizziness,

weakness, shaking, nausea, stomach cramps, diarrhea, sweating.

• Irritation Effects - Minimal rashes, but readily absorbed through the skin.

• Delayed/Allergic Effects - Loss of appetite, weakness, weight loss, and general feeling of sickness. Occasionally permanent harm to brain and nervous system.

• Irreversible inhibition of AChE

Page 37: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

N-Methyl Carbamates Effects

• Action on Human System - Reversible changes in acetylcholinesterase enzyme in tissues.

• Systemic Effects - Headache, dizziness, weakness, shaking, nausea, stomach cramps, diarrhea, sweating.

• Irritation Effects - Minimal rashes, but readily absorbed through the skin.

• Delayed/Allergic Effects - Loss of appetite, weakness, weight loss, and general feeling of sickness.

• Reversible inhibition of AChE

Page 38: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Organophosphates and Carbamates

• Organophosphates– Chlorpyrifos*– Diazinon*– Trichlorfon*– Parathion*

• Carbamates– Carbaryl (Sevin)– Propoxur (Baygon)*

Chemicals which are derived from phosphoric and carbamic acid and bond with cholinesterase

Acute toxicityNot persistentHyper-excitationInsect flips on back with legs twitchingSulfur in formulation often causes strong odor

*EPA hit list or not common in UPM

Page 39: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Organophosphates

R -- O -- P

OO -- R’

S -- R”Phosphorothioate

H -- O -- P

OO -- H

O -- H

Phosphoric Acid

Chlorpyrifos ((Dursban)

Page 40: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Carbamates

Carbamate

CH3 -- N -- C

O

O -- HCarbamic Acid

CH3 -- N -- C

O

O -- RCarbaryl (Sevin)

Page 41: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Dursban Kill• Vomit and excretion in 8 hours• Death in 9 hours

Page 42: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Dursban: Chlorpyrifos

• Proven Residual Control– Effective control makes it the perfect product for

maintenance accounts. – Ability to provide control for several weeks,

keeps customers protected between treatments.

• Broad Label for Varied Applications– Broad labeling allows use for almost any

application indoors or out. – Designed to be used in homes and apartments,

hospitals, stores, manufacturing plants and warehouses.

Page 43: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Organophosphate and Carbamate Labels

• Dursban Pro• Dursban TC• Diazinon G

Page 44: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Insecticides that Affect the

Nervous System Nervous System

propoxurcarbaryl

permethrindeltamethrin

PyrethroidsDDT

Sodium Channel

CarbamatesPhosphates

Neonicotinoids

Acetylcholine receptor

Acetyl-cholinesterase

chlorpyrifosmalathiondiazinon

Spinosyns

imidaclopridthiamethoxam

Page 45: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Acetylcholine Receptor• Mimics

acetylcholine on the receptor– Nicotinic receptor is

a type of ACh receptor that is sensitive to nicotine

• Cannot be broken down by AChE

• Imidacloprid turns nerve impulse on but AChE does not degrade it

• Similar overstimulation as seen with OPs and Carbs

Page 46: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Neonicotinoids• Imidacloprid (subgroup: pyridylmethylamine)

– Advantage – pet treatment– Merit -- turf ornamentals

• Water soluble• Systemic in plants

– Premise – termites• Affects insects first by paralyzing mouthparts

– Bayer Advantage OTC

• Thiamethoxam (subgroup: nitroguanidine)– Used in crops– Working on urban and landscape/turf/ornamentals label

• (Subgroup: nitromethylene)

Page 47: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Premise: Imidacloprid

• No odor • Not repellent to termites• Low risk to your family, your pets, your

home• Premise causes a range of effects:

– Pests stop feeding – Premise Plus Nature™. This phenomenon makes termites

susceptible to infection by naturally occurring organisms.

• Lateral Soil Movement causes spread to ensure thorough soil coverage

Page 48: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Neonictinoid Labels

• Premise• Advantage• Bayer Advantage

Page 49: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Spinosyns

• Saccharopolyspora spinosa fermetation product

• Soil dwelling• Success*, Naturalyte*, Tracer*

(Dow AgroSciences)• Testing for UPM

Page 50: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Insecticides that Affect the Nervous System

Nervous System

propoxurcarbaryl

permethrindeltamethrin

PyrethroidsDDT

Sodium Channel

chlordaneheptachlor

Cyclodienes

fipronil

Phenyl pyrazoles

GABA Receptor

CarbamatesPhosphates

Cholinesterase

chlorpyrifosmalathiondiazinon

Neonicotinoids

Acetylcholine receptor

Spinosyns

imidaclopridthiamethoxam

Page 51: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

MOA: GABA Antagonist

• Phenylpyrazole (fipronil), cyclodienes• Antagonists of GABA activated chloride channels• GABA Antagonists: chemicals that bind to but do

not activate GAMMA-AMINOBUTYRIC ACID receptors, thereby blocking the actions of endogenous GAMMA-AMINOBUTYRIC ACID or GAMMA-AMINOBUTYRIC ACID agonists.

• GABA can’t bind to receptor• Doesn’t activate channel (doesn’t open)• Interferes with (prevents) the passage of chlorine

ions through the channel.• Concerns with cross resistance with other

GABAergic insecticides

Page 52: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

GABA

GABA receptor

GABA Receptor in Central Nervous

System• Phenylpyrazoles or• Fiproles

GABA-receptors

GABAChloride ions

Fipronil

Page 53: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Phenyl pyrazoles• Fipronil

– Chipco Choice -- mole crickets & grubs– Firestar, Ouver-N-Out, (Ceasefire)--

fireants– Termidor -- termites– Regent -- corn– Frontline -- flea & tick– MaxForce FC -- cockroaches and ants

Most lipophilic insecticide ever discovered

Persistent in soilSpread among social insects on

bodies4 months of residual on dogs (binds

to oils in sebaceous glands)

Page 54: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

MaxForce FC kill• Loss of muscle control at 17 hours• Death at about 20 hours

Page 55: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

MaxForce FC: Fipronil

• Unique mode of action:– long-term control – faster results than other ant and cockroach

bait products

• Fipronil is a highly active, broad-spectrum insecticide from the phenyl pyrazole family– discovered in 1987– low doses– highly effective against a broad range of

insect pests, including ants and roaches

Page 56: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Phenyl Pyrazole Labels

• MaxForce FC Bait Stations • Termidor

Page 57: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Insecticides that Affect the

Nervous System Nervous System

propoxurcarbaryl

permethrindeltamethrin

PyrethroidsDDT

Sodium Channel

abamectin

Avermectins

chlordaneheptachlor

Cyclodienes

fipronil

Phenylpyrazoles

GABA Receptor

CarbamatesPhosphates

Cholinesterase

chlorpyrifosmalathiondiazinon

Page 58: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

MOA: GABA Agonist• Avermectins• Bind to GABA (Gamma-Amino-Butyric Acid

gated chloride channel• Opens channel• Chloride influx• Cannot reach threshold for action potential• Causes membrane to hyperpolarize, making

it less excitatory, decreasing nerve transmission

• Result: flaccid paralysis and death

Page 59: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Avermectins

• Abamectin– Avert --

cockroaches– Advance -- ants

Produced from soil microbials. Stomach poison for ants and cockroaches

slow actinglow toxicity to mammals

Page 60: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Avert Kill• 22 hours to nerve effects• 40 hours to kill

Page 61: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Avert and Advance

• Attractive, long-lasting bait formulations

• Highly effective active ingredient

Page 62: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Abamectin Labels

• Avert• Advance• Raid

cockroach bait (class)

Page 63: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Chlordane kill• 15 hours to loss of muscle control• 33 hours to kill

Page 64: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226

Modes of Action of Insecticides

Nervous System Energy Production

Cuticle Production

Water Balance

Endocrine System

Page 65: Pesticides: Types and Modes of Action ENY 3225 or ENY 5226