Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
23 Cards in this Set
- Front
- Back
|
How do we classify arthropods & what classes do we have?
|
Crustaceans – >5 pairs of legs
Insects – 3 pairs of legs Arachnids – 4 pairs of leg |
|
|
Describe the features of arthropods including their respiratory system, circulatory system, and gut.
|
-chitinous exoskeleton called the cuticle, impermeable to water & many drugs
-muscles are internal & attached to exoskeleton -CIRCULATION: open circulatory system, blood free in haemocoel -GUT: Have mouth, gut & anus, as well as malpighian tubes (type of excretory and osmoregulatory system) →salivary glands are important in transmitting pathogens -RESPIRATION: can have a tracheal system opening through spiracles or stigma(ta) onto the exoskeleton (can apply chemicals and kill them by blocking it) or gills in aquatic arthropods or diffusion of O2 through the cuticle -NERVOUS SYSTEM: (*important for drugs) – consists of ganglia or brain surrounding esophagus, longitudinal nerves with a ganglion in each segment →Neurotransmitters: Ach & GABA LIFE CYCLES: moult stages are called “instars” →metamorphoses are common |
|
|
What is an ectoparasite? What is an example? What is an endoparasite?
|
ECTOPARASITE - parasite found on the outside of the body e.g. TICK
ENDOPARASITE – lives on inside of body |
|
|
What is an obligate parasite? What is an example?
|
-organisms whose existence is totally dependent upon the host e.g. FLEAS
|
|
|
What is a facultative parasite? What is an example?
|
-can multiply without a host but under some circumstances can become parasitic
-e.g. blowflies whose maggots normally develop in decaying organic matter may also develop in wounds on animals |
|
|
What is a permanent parasite? What is an example?
|
-on the host at all times & all life stages e.g. LICE
|
|
|
What is an intermittent parasite? What is an example?
|
-visits the host periodically e.g. MOSQUITO
|
|
|
Why are arthropods important pathologically?
|
-may kill host e.g. sheep scab
-may cause production loss – body lice in sheep -may cause irritation e.g. mosquitoes -may act as vectors for viruses, bacteria, or other parasites |
|
|
What is an example of a repellant?
|
✤COMPOUNDS TO CONTROL ARTHROPODS
❀REPELLANTS →DEET (N, N-dethyl-m-toluamide) →dipropyl isocinchomeronate →piperonyl butoxide →citronella |
|
|
What is an example of a chlorinated hydrocarbon? How does it act? How long does it persist in the environment?
|
✤COMPOUNDS TO CONTROL ARTHROPODS
❀CHEMICALS ACTING ON THE NERVOUS SYSTEM ✥Chlorinated Hydrocarbons →DDT →Lindane (gamma benzene hexachloride) →Dieldrin, Endrin -interfere with ion transport across the membranes of axons, produce hyper-excitability -PERSISTENCE: persistent for a LONG time in environment; banned for use in food animals -many species of insects exhibit resistance to DDT |
|
|
How do organophosphates act? Are they toxic to vertebrates? How long do they persist in the environment? How do we administer them? What is an example?
|
✤COMPOUNDS TO CONTROL ARTHROPODS
❀CHEMICALS ACTING ON THE NERVOUS SYSTEM ✥Organophosphates -interfere with acetylcholine-esterase activity (muscarinic effects of Ach) -binding with ACh Esterase is reversible -highly effective insecticides, also have some activity against nematodes -Toxicity to Vertebrates: due to parasympathetic effects – prevent with atropine -PERSISTENCE: rapidly broke down in environment -short period of activity (24-48 hours) -non-cumulative -ADMINISTRATION: Topical or Oral EXAMPLES: →Malathion – commonly used for control of fleas as shampoo -garden spray, can be used for larval and pupal fleas →Diazinon – commonly used to jet sheep for blowfly control -many populations of flies resistant to Diazinon and hence to other organophosphates →Cythionate – used orally in dogs for flea control →Trichlorphon – used commonly for control of bots in horses, oral →Dichlorvos – used as antihelmintic; present in “pest strips”, flea colors →Maldisone – spray-on insecticide for pigs |
|
|
How do carbamates act? How long do they persist? Is binding reversible? What is an example?
|
✤COMPOUNDS TO CONTROL ARTHROPODS
❀CHEMICALS ACTING ON THE NERVOUS SYSTEM ✥Carbamates -also bind to and inactivate ACh Esterase; main effect is in ganglia -binding is reversible -antidote is atropine -PERSISTENCE: duration of effects is longer than OPs, can be 4-6 weeks EXAMPLES: →Carbaryl – powder or spray for flea control in dogs & cats -treat weekly -constituent of flea collars →Propoxur (Baygon) – shampoos, aerosols, powders and flea collars -general ectoparasite control -many arthropod parasites are resistant to carbamates |
|
|
How do Formamidines act? What are they effective against? What is an example?
|
✤COMPOUNDS TO CONTROL ARTHROPODS
❀CHEMICALS ACTING ON THE NERVOUS SYSTEM ✥Formamidines -inhibit monoamine oxidase -highly effective against ticks and mites EXAMPLES: →Amitraz – highly effective against OP resistant cattle ticks -highly effective against Demodex in dogs if treated 2-3 times at 13 day intervals |
|
|
What are pyrethrins derived from? How do they act? Are they toxic to vertebrates? How long do they persist for?
|
✤COMPOUNDS TO CONTROL ARTHROPODS
❀CHEMICALS ACTING ON THE NERVOUS SYSTEM ✥Botanicals ✶Pyrethrins -derived from flower of Chrysanthemum cinerariaefolium -disrupt Na+ & K+ fluxes in neurons -effective insecticides -TOXICITY: low toxicity, except FISH -PERSISTENCE: rapidly broken down, effective for less than 24 hours -available as powders, aerosols, fogs, mists, shampoos |
|
|
How are pyrethroids different than pyrethrins? How long do they persist for? Are they toxic to vertebrates? What is an example?
|
✤COMPOUNDS TO CONTROL ARTHROPODS
❀CHEMICALS ACTING ON THE NERVOUS SYSTEM ✥Botanicals ✶Pyrethroids -synthetic pyrethrim-like compounds -disrupt Na+ & K+ fluxes in neurons -more potent; greater knockdown effect -PERSITENCE: more stable in environment, last 7-14 days -TOXICITY: low EXAMPLES: fenvalerate, permethrin (scabies in humans), cypermethrine -basis of back-line lice control methods (e.g. cypermethrin, deltamethrin) -also used in dips (e.g. cyhalothrin) |
|
|
What are macrocyclic lactones based on? How are they administered? What are they effective against? How do they act? What is an example?
|
✤COMPOUNDS TO CONTROL ARTHROPODS
❀CHEMICALS ACTING ON THE NERVOUS SYSTEM ✥Macrocyclic Lactones -ivermectins and milbemycins are synthetic chemicals based on those secreted by soil inhabiting micro-organisms (Streptomyces spp.) -administered orally, topically, or parenterally -highly potent compounds against blood or tissue feeding arthropods & nematodes -act on glutamate-gated chloride channels MAJOR GROUPS: →Avermectins: EXAMPLES: ivermectin, abamectin, selamectin →Milbemycins: EXAMPLES: moxidectin |
|
|
What are neonicotinoids? Are they toxic to mammals? How long do they persist for? What is an example?
|
✤COMPOUNDS TO CONTROL ARTHROPODS
❀CHEMICALS ACTING ON THE NERVOUS SYSTEM ✥Neonicotinoids -synthetic insecticides designed specifically for nicotinic receptors in arthropods -TOXICITY: low toxicity to mammals -administered topically & translocated in skin -PESISTENCE: may persist in shed keratin and kill arthropods in the environment -period of activity 2-4 weeks EXAMPLES: →Imidacloprid – blocks nicotinic receptors (Advantage), nitenpyram (Capstar) →Fipronil – blocks GABA receptors (Frontline) →Flea control |
|
|
What are growth regulators? How do we administer them? Are they toxic? What are they primarily used to control? What is an example?
|
❀GROWTH REGULATORS
-analogues of insect juvenile growth hormones -interfere with growth/moulting/egg laying -TOXICITY: low -administration is oral (or topical) -DO NOT KILL ARTHROPODS IMMEDIATELY -used primarily to control Lucilia cuprina. Highly effective, but maggots are not killed quickly. Unlikely that resistance will develop. EXAMPLES: →Methoprene, Lufenuron, Pyriproxyfen – used in flea control →Cyromazine – used for blow flies in sheep →Fluazuron – used to control cattle tick |
|
|
What are the general features of the class crustacea?
|
CLASS CRUSTACEA
-often numerous body segments -five pairs of legs or more -many aquatic -includes common groups such as crabs, yabbies etc. |
|
|
What are the features of the subclass copepoda?
|
SUBCLASS: Copepoda
-free living copepods act as intermediate hosts of tapeworms (Spirometra) and nematodes (Gnathostoma) e.g. Cyclops -many are important ectoparasites of fishes -Lernea spp. and Argulus foliaceus are pathogenic copepods of aquarium fish |
|
|
Describe the features of the subclass isopodata
|
SUBCLASS: Isopodata
-ectoparasites of marine fish and crustaceans -“tongue biters” are large isopods found in the mouths of marine fishes |
|
|
Describe the features of the subclass Pentastomida
|
SUBCLASS: Pentastomida
-internal parasites of respiratory system of birds, mammals, & reptiles -elongate, no appendages -indirect life cycle -respiration cutaneous -2 hooks on either side of mouth -eggs contain embryo when laid |
|
|
What is Linguatula serrata? What does it look like? Describe the lifecycle. What species does it infect? What symptoms do we see? How do we diagnose & treat it?
|
CLASS CRUSTACEA
SUBCLASS: Pentastomida ✤Linguatula serratta -“tongue worm” of dog and fox -tongue shaped, anterior end wider -2 hooks on either side of mouth -cuticle with annular striations LIFECYCLE: -in nasal passages of dog, lays eggs, eggs passed in nasal discharge or feces. Sheep, or rabbit take it up and it burrows into muscle around stomach and matures. Humans or dogs eat undercooked rabbit. Hatches in stomach and migrates up to nasal cavity. -eggs contain larvae when laid -larvae live in mesenteric lymph nodes of herbivores and occasionally the lung or liver -when eaten grow to maturity in 6 months -SPECIES: sheep, cattle, pigs, dogs, cats, and man reported infected -SYMPTOMS: worm doesn’t appear to cause any ill effects but may cause sneezing and a nasal discharge -DIAGNOSIS: Find egg in faeces TREATMENT: surgery, ivermectins -found in the respiratory passage of large snakes -intermediate stages in mesenteric nodes of a number of animals including man and other primates |
