Pesticides

Mode of action

1

MOA Insektisida Acetylcholinesterase (AChE) inhibitors GABA-gated chloride channel antagonists Sodium channel modulators Nicotinic acetylcholine receptor (nAChR) agonists Nicotinic acetylcholine receptor (nAChR) allosteric

activators Chloride channel activators Juvenile hormone mimics Miscellaneous nonspecific (multi-site) inhibitors Mite growth inhibitors

2

Microbial disruptors of insect midgut membranes Inhibitors of mitochondrial ATP synthase Uncouplers of oxidative phosphorylation via disruption of

the proton gradient Nicotinic acetylcholine receptor (nAChR) channel blockers Inhibitors of chitin biosynthesis, type 0 Inhibitors of chitin biosynthesis, type 1 Moulting disruptor, Dipteran Ecdysone receptor agonists Octopamine receptor agonists Mitochondrial complex III electron transport inhibitors

3

Mitochondrial complex I electron transport inhibitors

Voltage-dependent sodium channel blockers Inhibitors of acetyl CoA carboxylase. Mitochondrial complex IV electron transport

inhibitors Mitochondrial complex II electron transport

inhibitors Ryanodine receptor modulators Compounds of unknown or uncertain MoA2

4

MOA Fungisida

nucleic acids synthesis RNA polymerase I adenosin-deaminase DNA topoisomerase type II (gyrase)

mitosis and cell division ß-tubuline assembly in mitosis cell division delocalisation of spectrin-like proteins

5

respiration complex I NADH Oxido-reductase complex II: succinate-dehydro-genase complex III: cytochrome bc1 (ubiquinol oxidase) at Qo

site (cyt b gene) complex III: cytochrome bc1(ubiquinone reductase) at

Qi site uncouplers of oxidative phosphorylation inhibitors of oxidative phosphorylation, ATP synthase ATP production complex III: cytochrome bc1 (ubiquinone reductase) at

Q x (unknown) site

6

amino acids and protein synthesis methionine biosynthesis (proposed) (cgs

gene) protein synthesis

signal transduction MAP/Histidine- Kinase in osmotic signal

transduction MAP/Histidine- Kinase in osmotic signal

transduction

7

lipid synthesis and membrane integrity phospholipid biosynthesis, methyltrans-

ferase lipid peroxidation (proposed) cell membrane permeability, fatty acids

(proposed) microbial disrupters of pathogen cell

membranes cell membrane disruption (proposed)

8

sterol biosynthesis in membranes C14- demethylase in sterol biosynthesis 14-reductase and 87- isomerase in

sterol biosynthesis 3-keto reduc-tase, C4- de-methylation squalene-epoxidase in sterol biosynthesis

9

cell wall biosynthesis trehalase and inositol-biosynthesis chitin synthase cellulose synthase

10

melanin synthesis in cell wall reductase in melanin biosynthesis dehydratase in melanin biosynthesis

host plant defence induction salicylic acid pathway

Multi-site contact activity Unknown mode of action

11

Acetylcholinesterase (AChE) inhibitors

AChEase is the enzyme responsible for the breakdown of the neurotransmitter acetylcholine (ACh). 

Organophosphate compounds are irreversible inhibitors of AChEase while carbamate compounds are reversible inhibitors of AChEase.

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13

14

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Acetylcholinesterase (AChE) inhibitors The reaction between an organophosphate

and the active site on AChEase (a serine hydroxyl group) results in the formation of an intermediate that undergoes partial hydroylsis with the loss of the "Z" group, leaving a stable, phosphorylated, permanently inhibited enzyme.

Signs and symptoms are prolonged and persistent. Without intervention, the toxicity will persist until sufficient amounts of "new" AChEase are synthesized in 20 to 30 days.

17

Acetylcholinesterase (AChE) inhibitors

Carbamate compounds attach to the serine hydroxyl group, the "X" group is removed by hydrolysis forming a carbamylated enzyme, and then decarbamylation occurs regenerating free, active AChEase. Carbamate pesticides are really just

poor substrates for AChEase.

18

GABA-gated chloride channel antagonists

Gamma Amino Butyric Acid Agonist vs antagonist

Both are mimic Agonists often mimic the action of a

naturally occurring substance (GABA). Whereas an agonist causes an action, an antagonist blocks the action of the agonist and an inverse agonist causes an action opposite to that of the agonist.

19

Chloride channels display a variety of important physiological and cellular roles that include regulation of pH, volume homeostasis, organic solute transport, cell migration, cell proliferation and differentiation

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21

Sodium channel modulators

22

Prolonged Repolarization alters the Na+ channels, they open

normally but are closed (inactivated) slowly. 

All of these factors reduce the rate at which repolarization occurs and increase the sensitivity of the neurons to small stimuli that would not elicit a response in a fully repolarized neuron.

23

Other MOA…????

24

Mode of Action:Herbicides

Movement in the plant Contact * Translocated *

Action in the plant Inhibit protein synthesis, photosynthesis, or

growth

Mode of Action:Contact Herbicide

One which causes injury to only the plant tissue to which it is applied, or one which is not appreciably translocated within a plant

Mode of Action:Translocated Herbicide

One which is moved within a plant from the point of application to the point of action; may be either phloem-mobile or xylem-mobile

The term is often misapplied to include only foliar applied herbicides which move downward from the leaves to the roots

Mode of Action: Animal Poisons (incl.Insecticides)

Contact poison *

Systemic poison *

Attractants * Pheromones Baits

Repellants *

Mode of Action:Systemic Insecticide

Pesticide which is moved within a plant from the point of application to the point where the insect will contact or ingest it

Mode of Action:Attractants

Pesticide which lures animals to a predetermined spot Pheromones are biochemicals either released by the

animal or synthesized which are sex attractants Baits are chemicals which entice animals for reasons

other than sex (smells like food)

Return

Mode of Action:Repellants

Pesticide which discourages animals from coming to a specific area

Many chemicals unrelated to sexual activity (due to smell or other physical characteristic) are repellant to animals

Pheromones in low concentration are attractive to animals but, often, in high concentration become repellant

Mode of Action:Life Stage Affected

Ovicide *

Larvicide *

Adulticide *

Mode of Action:Life Stage Affected

Ovicide

Kills eggs

Mode of Action:Life Stage Affected

Larvicide

Kills larval stage (immature) insects

Mode of Action:Life Stage Affected

Adulticide

Kills adult insects