GTBOP Moodle Matching Exercises

Principles of Insecticide Mode of Action — Dr. Michael Scharf

Webinar Date: October 18, 2017 Series: Structural Pest Control Activity Type: Matching Exercises Exercises: 3 Total Pairs: 26 (8 + 10 + 8)


CHAIN OF CUSTODY

  • Source documents: Corrected SRT (GTBOP_Transcript_2017-10-18_InsecticideMOA.srt) + Archive Package (GTBOP_Archive_Summary_2017-10-18_InsecticideMOA.md)
  • All terms, definitions, and relationships derived exclusively from presentation content

Matching Exercise 1: Insecticide Classes and Their Target Sites

Timestamp Reference: 28:40 – 39:05 (primary coverage area) Type: Product-Target Site Matching

Instructions: Match each insecticide class in Column A with the target site it affects in Column B. Note: Column B contains two extra items.

# Column A Column B
1 Pyrethroids a) Chloride channels
2 Fipronil (phenylpyrazole) b) Acetylcholine receptor
3 Nicotinoids c) Muscular calcium channels
4 Organophosphates and carbamates d) Axonal sodium channels
5 Diamides (chlorantraniliprole) e) Acetylcholinesterase enzyme
6 Indoxacarb (oxadiazine) f) Mitochondria (energy production)
7 Abamectin (avermectin) g) Chitin synthesis enzymes
8 Chitin synthesis inhibitors h) Glutamate-gated chloride channels
i) Juvenile hormone receptors
j) Axonal sodium channels (blockage)

Answer Key: 1 → d, 2 → a, 3 → b, 4 → e, 5 → c, 6 → j, 7 → h, 8 → g

Notes:

  • Items 1 and 6 both target sodium channels but through opposite mechanisms (stimulation vs. blockage), which is why they map to separate entries (d and j). This distinction is a key teaching point from the presentation.
  • Distractors: (f) mitochondria and (i) juvenile hormone receptors are legitimate target sites discussed elsewhere in the presentation but do not match the classes listed in Column A.

Source in transcript: Blocks 301–343 (target site roadmap), 346–362 (sodium channels), 363–387 (chloride channels), 388–407 (acetylcholine), 429–444 (diamides), 466–482 (IGRs)


Matching Exercise 2: Insecticide Mode of Action Effects

Timestamp Reference: 17:51 – 47:00 (spans full classification section) Type: Product-Effect Matching

Instructions: Match each insecticide or insecticide class in Column A with the physiological effect it produces in insects, as described by Dr. Scharf, in Column B. Note: Column B contains two extra items.

# Column A Column B
1 Pyrethroids / pyrethrins a) Blocks chloride channels, causing nervous system excitation
2 Fipronil b) Stimulates muscular calcium channels, causing contraction followed by energy depletion and paralysis
3 Indoxacarb c) Stimulates sodium channels, causing rapid knockdown and excitation
4 Organophosphates d) Inhibits chitin synthesis enzyme, causing death during molting
5 Diamides e) Blocks sodium channels, causing paralysis ("on switch stuck in off position")
6 Juvenile hormone analogs (pyriproxyfen) f) Inhibits acetylcholinesterase, causing excitation from neurotransmitter buildup
7 Chitin synthesis inhibitors g) Mimics juvenile hormone, causing cuticle deformation and extra juvenile stages
8 Abamectin h) Stimulates chloride channels, causing inhibition and paralysis
9 Silica gel / diatomaceous earth i) Abrades waxy cuticle layer, causing water loss and dehydration
10 Nicotinoid-pyrethroid combinations j) Stimulates acetylcholine receptors and sodium channels simultaneously (potentiation)
k) Disrupts mitochondrial respiration, depleting cellular energy
l) Blocks acetylcholine receptors, preventing nerve signal transmission

Answer Key: 1 → c, 2 → a, 3 → e, 4 → f, 5 → b, 6 → g, 7 → d, 8 → h, 9 → i, 10 → j

Notes:

  • This exercise tests understanding of both the target site AND the specific mode of action (stimulation vs. blockage vs. inhibition) — the core teaching framework of the presentation.
  • Distractors: (k) mitochondrial disruption is discussed for products like hydramethylnon but is not paired with any Column A item; (l) is a plausible-sounding but incorrect mechanism not described in the presentation.

Source in transcript: Blocks 184–205 (four modes of action), 346–362 (sodium channels), 363–387 (chloride channels), 388–407 (acetylcholine), 408–420 (combinations), 429–444 (diamides), 466–482 (IGRs), 499–511 (dusts)


Matching Exercise 3: Practical Factors Affecting Insecticide Performance

Timestamp Reference: 48:15 – 56:30 (practical factors section) Type: Timing-Practice Matching

Instructions: Match each practical factor or scenario in Column A with the correct explanation or outcome described by Dr. Scharf in Column B. Note: Column B contains two extra items.

# Column A Column B
1 Excess food in a cockroach account a) Can pass insecticide through two digestive tracts and still affect a third individual
2 Dirt and grease on treated surfaces b) Physically bind and tie up insecticides, reducing their effectiveness
3 Cockroach secondary/tertiary kill c) Enables slow-acting insecticides to spread through food sharing and grooming
4 Trophallaxis and allogrooming in social insects d) Competes directly with bait placements, reducing consumption by target pests
5 Flea larvae exposed through adult flea feces e) Causes the insecticide's active ingredient to degrade faster in the environment
6 UV light exposure on raw insecticides f) Larvae consume insecticide-laden feces of treated adults as a nutritional source
7 Formulations (inerts, stabilizers, attractants) g) Enhance stability, extend longevity, improve safety, and keep active ingredients dissolved in water
8 Product rotation every 3 months or monthly h) Helps manage resistance by alternating between different modes of action
i) Increases the LD50 of the product, making it less toxic to target pests
j) Converts neurotoxic insecticides into non-repellent formulations

Answer Key: 1 → d, 2 → b, 3 → a, 4 → c, 5 → f, 6 → e, 7 → g, 8 → h

Notes:

  • This exercise bridges the gap between toxicology and practice — the section of the presentation Scharf described as "where toxicology interfaces with practice."
  • Distractors: (i) is plausible-sounding but reverses the relationship (formulations don't increase LD50 for targets); (j) is a fabricated mechanism not described in the presentation.

Source in transcript: Blocks 515–547 (stability and formulations), 548–567 (pest behavior), 568–585 (sanitation), 586–611 (resistance management)


Moodle Activity Verification

  • [x] All terms, definitions, and relationships derived from presentation content
  • [x] Timestamp references verified against corrected SRT
  • [x] No external knowledge required to answer correctly
  • [x] Matching items unambiguous based on presentation content
  • [x] 1–2 plausible distractors included per exercise to prevent elimination guessing
  • [x] Answer keys unambiguously correct per speaker's content
  • [x] Exercises cover early (target sites), middle (modes of action and effects), and late (practical factors) presentation content