Mode of Action Flashcards
Phenylpyrozole
Active Ingredients include: Fipronil
Neurological Target Site: Chloride Channels
Fipronil binds to and blocks the GABA receptor on the post synapse nerve cell. This blockage prevents GABA from binding to the receptor site, which then prevents the influx of chloride ions into the post-synapse nerve cell. Because Chloride ions limit and balance the electrical activity within nerve cells, blocking chloride influx leads to rapid uncontrolled nerve firing throughout the nervous system, resulting in tremors and death.
Neonicotinoid
Active Ingredients include: imidacloprid, dinotefuran, thiamethoxam, clothianidin, acetamiprid
Neurological Target Site: Acetylcholine System
the neonicotinoid binds to the acetylcholine (Ach, a neurotransmitter) receptor on the post-synapse nerve cell. Under normal conditions, Ach only binds to this receptor for milliseconds at a time, resulting in short controlled nerve stimulation. The neonicotinoid binds to the receptor for very long periods, approximately minutes or longer. This action results in nerve hyper-stimulation causing tremors and death.
Pyrethroid
Active Ingredients include: bifenthrin, permethrin, cyfluthrin, beta-cyfluthrin, deltamethrin, cypermethrin, lambda-cyhalothrin
Neurological Target Site: Sodium channels
Disrupt normal nerve functions in a region of the nerve cell known as the axon. Their mode of action is to inhibit the on/off switch of nerve cells, called sodium channels, by delaying the rate at which they close, or turn off. This results in uncontrolled, uninterrupted nerve firing seen as a convulsing insect which quickly dies.
Pyrrole
Active Ingredients include: Chlorfenapyr
Target Site: Energy Production
Clorfenapyr must be converted by enzymes within the insect to an active form by a process called activation. Through activation Clorfenapyr is converted to a new molecule (referred to as a metabolite) that is insecticidal. Interestingly, the metabollite is toxic to mammals as well, however, mammals lack the necessary enzyme to make the conversion from inactive to active. The mode of action of chlofenapyr’s activated metabolite is that it destroys the mitochondria’s ability to supply energy to meet the insects needs. This results in paralysis and death.
Juvenile Hormone IGR
Active Ingredients include: hydroprene, methoprene, pyriproxyfen, fenoxycarb
Target Site: Maturation Process
The Juvenile Hormone Analog (JVA) mimics a naturally occurring chemical in immature insect called juvenile hormone. Juvenile Hormone is an important regulator of insect growth and development, including the natural maturation process. The presence of Juvenile hormone in immature insects keeps them from becoming adults - thus the name. Naturally, as an insect matures its level of juvenile hormones decrease through a decline in production allowing the transition from an immature insect to adulthood. In adult insect juvenile Hormone regulates the production of sperm in males and egg production in females. Since the JVA mimics the natural hormone in insects the the Juvenile Hormone level is kept high, keeping the insect from developing into a sexually mature adult. Sterilization and death often occur.
Oxadiazine
Active Ingredients include: Indoxicarb
Neurological Target Site: Sodium Channels
Indoxicarb must be converted by enzymes within the insect to an active form by a process called activation. Through activation indoxicarb is converted to a new molecule (referred to as a metabolite) that is insecticidal. Interestingly, the metabollite is toxic to mammals as well, however, mammals lack the necessary enzyme to make the conversion from inactive to active. This activated metabolite targets the sodium channels along the axon and tightly binds to the sodium channels which are the on/off switches of the nerve cell. The sodium channels are completely blocked off preventing sodium ion flow into nerve cells. In a manner completely opposite of pyrethroids, insects poisoned with indoxicarb appear paralyzed and limp, and are incapable of movement.
