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Module 20: Global Vet Med > Control of Ticks on Livestock > Flashcards

Control of Ticks on Livestock Flashcards

1
Q

what are paralysis ticks

A

Salivary neurotoxins that are variably reversible cause progressive paralysis

Ixodes holocyclus toxin is similar to botulinum toxin

Karoo paralysis tick Ixodes rubicundus (Southern Africa)

Paralysis tick Ixodes holocyclus (Southeastern Australia)

American dog tick Dermacentor variabilis (USA)

Rocky Mountain wood tick Dermacentor andersoni (USA)

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2
Q

what diseases do ixodes ricinus cause

A

Babesia divergens

Anaplasma phagocytophilum

Staphylococcus aureus tick pyemia

Louping ill virus

Diverse rickettsiae

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3
Q

what dieseases do dermacentor reticulatus cause

A

Babesia spp

Anaplasma marginale

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4
Q

what diseases do Haemaphysalis longicornis cause (autralasia and asia pacific)

A

Theleria buffeli/orientalis and others

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5
Q

what diseases do Rhipicephalus microplus (Australasia & Asia Pacific)

A

Babesia bigemina

B bovis

A marginale

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6
Q

what diseases do Rhipicephalus microplus & R decoloratus (africa) cause

A

Babesia bigemina

B bovis

A marginale

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7
Q

what diseases do Amblyomma variegatum & A herbraeum cause (africa)

A

Ehrlichia rumination known as heartwater

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8
Q

what disease does

Rhipicephalus appendiculatus

cause

A

Theileria parva East-Coast-Fever (ECF)

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9
Q

how many hosts does I ricinus have and how long is the life cycle

A

3 host tick with 3 year life cycle

Hosts:

Larvae on small mammals, birds

Nymphs on rabbits

Adults on ruminants

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10
Q

what environmental conditions do I ricinus need

A

Need >90% humidity

Questing when >10ºC

Feeding activity peaks April & May in most of UK

In high rainfall areas there is feeding also in Aug and Nov

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11
Q

what is the most important species of tick globally

A

r microplus

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12
Q

what is R microplus distribution limited by

A

mean temp

need <4 months <16C and rainfall

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13
Q

what is the lifecycle of R microplus

A

1 host tick

18-35 days on single host

Range of total LC 42-300 days

3-5 generations per year

Host include cattle, horses, small ruminants, wild ungulates

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14
Q

what are the impacts of ecology of r microplus

A

Simple life cycle

Strategic control programmes relatively simple

High fecundity — potential for rapid and massive infestation

Single host lifecycle with potentially low refugia accelerates acaricide resistance

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15
Q

what are the impacts of ticks

A

TBD transmission

Reduced growth rates

Reduced production

Anemia

Tick worry pyoderma

Hide damage

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16
Q

what does host density have to do with tick control

A

No host no ticks

The extent to which wildlife hosts can maintain tick populations varies among species

Re-stocking after periods with few or no cattle will increase tick problems

17
Q

what does host resistance have to do with control

A

Some breeds more resistant than others

18
Q

what does temperature have to do with tick control

A

Low temperatures retard growth but don’t kill ticks unless temperatures are extreme

High temps shorten survival but accelerate development

Very high temperatures and low humidity are lethal to ticks

19
Q

what does humidity have to do with tick control

A

Desiccation and inundation can both be lethal to ticks

Ticks will survive flooding and are dispersed widely by floods

Desiccation effects on the stage affected

20
Q

what does vegetation have to do with tick control

A

Ticks make use of vegetation to find their hosts and also to protect themselves from direct sun

In the absence of vegetation, survival times of larvae are much reduced

21
Q

what are the eradication requirements

A
  1. Continuously treat all possible hosts for the maximum period that free-living ticks can survive at intervals that are less than the minimum parasitic phase
    * ex. R. microplus this means 6-8 treatments every 3 weeks during early summer
  2. Strong legislation
  3. Full or regional compliance
  4. Effective acaricide
  5. Effective methods of application
22
Q

what are the pros and cons of eradication

A

Pros: ends needs for treatment

Cons: rarely successful, if fails likely to increase resistance to acaricides, if successful, population susceptible to TBDs

23
Q

what is reactive vs strategic control

A

Strategic control is sometimes confused by farmers and advisers with reactive, suppressive control or threshold control

A “suppressive” or “reactive approach” might be expected to result in farmers applying treatments at times corresponding with the yellow arrows

“Strategic” approach treatments are applied at predetermined times to maximize their impact on the total population of ticks on any given area of land

24
Q

what are the major acaricide groups

A

Arsenic

Organochlorines (OC)

Organophosphorus (OP)

Carbamates

Synthetic pyrethroids (SP)

Macrocyclic lactones (ML)

Amidines

Insect acarine growth regulators

Phenylpyrazoles

25
Q

what are organochlorides

A

interfere with nerve conduction (na ion channels)

effective on contact

toxicity & environmental concerns

widespread resistance

26
Q

what are organophosphates

A

Esters of phosphoric acid

Bind AChE (responsible for breakdown of ACh)

Effective on contact

Still used in UK and USA

Human toxicity

Widespread resistance

27
Q

what are synthetic pyrethroids

A

Cypermethrin, flumethrin, permethrin

Esters of chrysanthemum acid

Depolarize axonal Na channels

Excitation then paralysis

Stable in field

Good against flies

Main products used in UK

Important hazard to aquatic life

Widespread resistance

Significant environmental impacts

28
Q

what are amidines

A

Amitraz, cymiazol

Effective on contact

Less effective on flies

Act on octopamine receptor

Important effect is detachment

Fewer toxicity and residue concerns

Biodegradable

Not available in Europe

Resistance common

29
Q

what are macrocyclic lactones

A

Ivermectin, moxidectin

Effective on ingestion

Widest range of target species

Concerns re aquatic and terrestrial arthropods

GABA agonists

Irreversible blockade of nerve transmission

Mainly for single host ticks

Broad spectrum — off target effects

Expensive

Don’t prevent TBD transmission

Resistance confirmed in Latin America

Known adverse effects on dung-associated arthropods

30
Q

what are acarine growth regulators

A

Fluazuron

Inhibit progression through stages

Single host species mainly

Don’t prevent transmission of TBDs

Problems with lactating cows — long withholding periods

Resistance confirmed in Latin America and Australia

31
Q

what are phenylpyrazoles

A

GABA-gated and glutamate-gated chloride channel blockade

Also effective on insects

Few products

Resistance widespread in Latin America

32
Q

what are the application methods

A

pour on

hand spray

spray race

plunge dip

33
Q

what are the pros and cons of pour on application

A

Expensive

Persistant

Easy application

34
Q

what are the pros and cons of hand spray application

A

Cheap

Not for eradication

Can fail due to incomplete coverage

Workplace health and safety issues

35
Q

what are the pros and cons of spray race application

A

Expensive

High maintenance requirement

Design is critical

36
Q

what are the pros and cons of plunge dip application

A

Theoretical best method but

Volume not certain — dilutions incorrect

Dilution by rain

Concentration by evaporation

Inadequate mixing

Cattle not effectively plunged

Inadequate stabilization

Acaricide resistance

37
Q

are there effective tick vaccines

A

Cattle vaccinated against tick-gut glycoproteins

Ticks suck blood with antibodies

Tick gut damaged and leaks

Don’t reproduce well

Some die

Mainly for R. microplus

New vaccine rages are being explored

38
Q

what are tick biopesticides

A

Not commercially available yet

Fungus (Metarhizium anisopliae) attacks tick

Applied by spray

Module 20: Global Vet Med (21 decks)

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