Tick talk:

What is a Tick
Tick talk:
Identification of Ixodidae (Acari) with notes on identification, ecology and phenology.
By
Dr. Gerald Fauske
Department of Entomology
North Dakota State University
What is a Tick
Image sources (left) Blog‐ Lazy Lizard tales http://lazy‐lizard‐
tales.blogspot.com/2009/02/ticked‐off.html ;
(right): Iowa State University, Entomology image gallery http://www.ent.iastate.edu/imagegal/ticks/iscap/i‐scap‐m.html
What is a Tick
• Phylum Arthropoda: Jointed‐legged animals
Image sources: (far right, top bottom) CDC Public Health Library http://phil.cdc.gov/phil/home.asp; (top center right) University of Florida extension http://edis.ifas.ufl.edu/IG140; (lower center right) University of Sao Paulo, Biomedical Sciences http://icb.usp.br/~marcelcp/Default.htm; (left, lower center) University of MI, Barry O’Conor http://insects.ummz.lsa.umich.edu/ACARI/index.html; (top far left) Gary Alpert, Harvard http://www.forestryimages.org/insects.cfm; (left, lower and upper center) Wikipedia http://en.wikipedia.org/wiki/Main_Page
Image source: Wikipedia http://en.wikipedia.org/wiki/Main_Page
What is a Tick
• Phylum Arthropoda: Jointed‐legged animals
– Class Arachnida: Arachnids
What is a Tick
• Phylum Arthropoda: Jointed‐legged animals
– Class Arachnida: Arachnids
• Order Acari: Mites and Tics
At present the are approximately 45,000 described species of Acari placed in about 70 families. This is thought to represent about 5% of the extant species.
Image source: Wikipedia http://en.wikipedia.org/wiki/Main_Page
What is a Tick
• Order Acari: Mites & Ticks
– Clade Acariformes
• Suborder Trombidiformes
– Prostigmata‐ incl. Velvet mites
• Suborder Sarcoptiformes
– Astigmata‐ incl. Mange mites – Oribatida‐ Soil mites
– Clade Opilioaraciformes (Harvestmen‐like mites)
– Clade Parasitiformes
• Suborder Mesostigmata‐ incl. Skin mites • Suborder Holothyrida‐ primitive mites
• Suborder Ixodida‐ Ticks
Image source: Mites and Ticks, a virtual introduction http://www.sel.barc.usda.gov/acari/index.html; (lower left) University of MI, Barry O’Conor http://insects.ummz.lsa.umich.edu/ACARI/index.html ; (lower center right) NYC Environmental and Forest Biology http://www.esf.edu/efb/faculty/norton.htm. What is a Tick
• Suborder Ixodida
– Family Argasidae: Soft Ticks
– Family Nuttalliellidae: one rare African species.
– Family Ixodidae: Hard Ticks
The approximately 860 species of ticks are placed in 22 genera and three families world wide. Image source: CDC, emerging infectous diseases http://www.cdc.gov/ncidod/eid/vol8no2/01‐0198‐G1.htm
Tick morphology
Tick morphology
Ixodidae: Hard ticks
Argasidae: Soft ticks
• Scutum absent.
• Scutum present. Image source: (left) CDC Public Health Library http://phil.cdc.gov/phil/home.asp ;
(right) Gary Alpert USDA http://www.forestryimages.org/insects.cfm
Mouthparts gnathosoma) visible from above.
Tick morphology
Ixodidae: Hard ticks
• Host finding:
– Haller’s organ for long distance host detection.
– Four segmented
palpi for host contact.
Image source: CDC Public Health Library http://phil.cdc.gov/phil/home.asp
• Mouthparts (gnathosoma) not visible from above.
Image source: (center right) Mat Pound USDA http://www.forestryimages.org/insects.cfm ;
(far right) Jim Gathany, (left chart) both CDC Public Health Library http://phil.cdc.gov/phil/home.asp
Tick morphology
Ixodidae: Hard ticks
• Host finding
• Haller’s organ.
– Proximal pit: Chemoreceptors.
– Distal pit: Humidity sensor. Chemoreceptors
sensitive to CO2
and Butyric acid.
Image source: (left) Gary Alpert, Harvard http://www.forestryimages.org/insects.cfm ;
(right) Uncyclopedia
http://uncyclopedia.wikia.com/wiki/Uncyclopedia:Templates/General
Tick morphology
Tick morphology
Ixodidae: Hard ticks
Ixodidae: Hard ticks
• Host finding
• Hypostome and the feeding process.
Palpi.
– Apical pit:
Mechanoreceptors.
Chemoreceptors.
Mechanoreceptors are both heat sensing and tactile. chemoreceptors ‘taste’
butyric acid and salts.
Image source: Nation Tick collection via Discover Life http://www.discoverlife.org/mp/20q?search=Ixodes+scapularis
Image sources: (right) Science learning network http://www.mos.org/sln/sem/needle.html ;
(left) Nation Tick collection via Discover Life http://www.discoverlife.org/mp/20q?search=Ixodes+scapularis
Tick morphology
Tick life cycle
Ixodidae: Hard ticks
• Feeding process.
• Adults
Adults mate on a host and after another blood meal, eggs develop. Female then leaves host for egg deposition.
Individual ticks have been known to survive for as long as 7 years without feeding under laboratory conditions. Image source: CDC Public Health Library http://phil.cdc.gov/phil/home.asp ; (lower left) Ticks and Lyme disease Vworkers forum http://forums.vwvortex.com/zerothread?cmd=print&id=3873597
Image source: CDC Public Health Library http://phil.cdc.gov/phil/home.asp
Tick life cycle
• Egg: Females lay eggs on soil or at the base of vegetation. A single tick (Ixodidae) may lay as many as 2,000‐ 18,000 eggs. Females of the Argasidae lay from 100‐ 200 eggs. Females die after egg deposition.
Image sources: (top) Cate Hill, Purdue, Stephen Wikel, UCHC http://www.entm.purdue.edu/igp/default.html; (bottom) CDC via Wikimedia
http://commons.wikimedia.org/wiki/File:Argas_spec_
columbidae.jpg
Tick life cycle
• Larvae
The six‐legged larva ecloses
from the egg and ascends vegetation where it waits for a passing host. Image sources: (top) Vermont Lyme network, Blacklegged tick http://www.vermontlyme.org/ticks.htm; (bottom) Lone star tick larva http://www.visitmonmouth.com/page.aspx?Id=2873
Tick life cycle
• Nymphs
After larvae have taken a blood meal from their host, they moult into the nymphal stage. Some species remain on the host for this process, most leave the host, moult, and then again ascend vegetation and lay in wait for a new host. Nymphs have eight walking legs but lack the genital plate of adult ticks.
Tick life cycle
• Adults
After Nymphs have fed from their host, they mould into an adult which then has a well developed genital plate and genitalia. As with the previous moult, some species remain on the host for this process, most leave the host, moult, and then again ascend vegetation and lay in wait for a new host. Image source: CDD
Image source: Penn State University dept of Entomology Image gallery http://www.ento.psu.edu/imagegallery/Ticks‐1.htm
http://www.cdc.gov/ncidod/dvbid/lyme/ld_transmission.htm
Differentiating immature stages from adult ticks
• Necessary for species identification in the family Ixodidae. Larvae: three pairs of walking legs.
Nymphs and adults: four pairs of walking legs.
Nymphs without well developed genital plate, about 1 mm in length.
Adults with well developed genital plate (eggs often visible in female ovaries). Specimens > 1 mm in length.
Note‐ based upon morphological characters, species identification is often not possible with immature stages.
Tick life cycle
• Phenology
– One host tick: larvae, nymphs and adults on a single host.
– Two host tick: larvae and nymphs on one host, adults on a second host. – Three host tick: each active life stage on a separate host. Image source: University of Georgia: http://www.vet.uga.edu/vpp/ivm/eng/ticks/biology/feed.htm
Image source: CDC Public Health Library http://phil.cdc.gov/phil/home.asp
Tick life cycle
Tick life cycle
Dermacentor variabilis: a 3 host tick
Ixodes scapularis: a 3 host tick
Image source Purdue University, drawing by Scott Charlesworth: http://extension.entm.purdue.edu/eseries3/view.php?article=articles/the_biology_and_medical_importance_of_ti
cks_in_indiana.txt&id=&section=Medical
Image source CDC: http://www.cdc.gov/ncidod/dvbid/LYME/ld_transmission.htm
Tick Anatomy
Image source: Ticks and Animal disease http://www.vet.uga.edu/vpp/IVM/ENG/ticks/intro.htm
Image source: CDC Public Health Library http://phil.cdc.gov/phil/home.asp
Tick Identification
Genus Ixodes
Distinguishing males from females
Non‐Ixodes genera: Dermacentor, Amblyoma, Haemaphysalis
and Rhipicephalus
Image sources: (top) Animal and Human Parasite organisms, Gary Upton, University of Kansas http://www.k‐
state.edu/parasitology/625tutorials/in
dex.html; (bottom) CDC Public Health Library http://phil.cdc.gov/phil/home.asp
Identification of Tick genera
• Ixodes‐ Ixodes scapularis: Black‐legged tick
– Anal groove encircling
anal plate.
– No festoons.
– Basis capituli
not angulate
Image source: CDC Public Health Library http://phil.cdc.gov/phil/home.asp
Ixodidae (Hard ticks)
Ixodes
Ixodes species of the upper Midwest (IA, MI, MN, ND, SD, WI)
These 13 species lack festoons. Anal sulcus as a ‘parabolic’ groove around anal plate.
• Species
I. angustus Neumann
I. banksi Bishopp
I. brunneus Koch
I. cookei Packard
I. dentatus Marx
I. kingi Bishopp
I. marxi Banks
I. muris Bishopp & Smith
I. ochotonae Gregson
I. scapularis Say
I. sculptus Neumann
I. spinipalpis Hawden & Nuttall
I. texanus Banks
• Common name
‐‐
Skunk tick
Bird Ixodes
Woodchuck tick
Eastern Rabbit tick Rotund tick
Squirrel tick
Mouse tick
‐‐
Black legged tick
Ground squirrel tick
‐‐
Raccoon tick
Ixodidae (Hard ticks)
Amblyomma, Dermacentor, Haemaphysalis, Rhipicephalus
•
Non‐Ixodes species of the upper Midwest (IA, MI, MN, ND, SD, WI)
These species have festoons. Anal sulcus as a semicircular groove posteriad of anal plate.
Distribution
IA, MI, MN, ND, SD, WI
MI, WI
WI
IA, MI. MN, SD, WI
IA, WI
IA, MI, ND, SD
MI, MN, ND, WI
MI, MN, SD, WI
SD
IA, MN, ND, WI
IA, MN, ND, SD, WI
ND, SD
IA, MI, WI
Identification of Tick genera
• Amblyomma‐ A. americana: Lone star tick
– Palpi longer than basis capitulum.
Image source Oklahoma State University http://www.ento.okstate.edu/ddd/insects/lonestartick.htm
• Species
• Common name
Amblyomma americanum
Dermacentor albipictus
Dermacentor andersoni
Dermacentor variabilis
Haemaphysalis leporuspalustris
Rhipicephalus sanguineus
•
Lone star tick
Winter tick
Rocky Mountain wood tick
American dog tick
Rabbit tick
Brown dog tick
Distribution
IA, strays in other states
MI, MN, ND, SD
ND. SD
IA, MI. MN, ND, SD, WI
IA, MI, MN, ND, SD, WI
strays in all states
Identification of Tick genera
• Dermacentor‐ D. variabilis: American dog tick
– Palpi and basis capitulum
not angulate.
– Palpi not longer than basis capitulum.
– Opisthosoma with
festoons.
Image source Oklahoma State University http://www.ento.okstate.edu/ddd/insects/lonestartick.htm
Identification of Tick genera
• Haemaphysalis‐ H. leporispalustris: Rabbit tick
– 2nd segment of palpus
angulate.
Image source: (left) University of Florida, IFAS Extension http://edis.ifas.ufl.edu/topic_fleas_and_ticks
(right) CDC Public Health Library http://phil.cdc.gov/phil/home.asp
Identification of Tick genera
• Rhipicephalus‐ R. sanguineus: Brown dog tick
– Basis capitulum
hexagonal
Image source: (left) University of Florida, IFAS Extension http://edis.ifas.ufl.edu/topic_fleas_and_ticks
(right) CDC Public Health Library http://phil.cdc.gov/phil/home.asp
Ticks and disease transmission
• Tick removal.
– Using a fine forceps, grasp the capitulum as close to the wound as possible.
– Apply steady upward force until tick is free. Part or all of the hypostome may remain in wound and can be treated as a sliver. – Do not apply a petroleum product to remove tick.
– Do not squeeze the opisthosoma.
– Do not heat tick with a match. Image source CDC: http://www.cdc.gov/ncidod/dvbid/Lyme/ld_tickremoval.htm
Summary
•
•
•
•
•
•
Ticks are Arthropods (Jointed legged animals). Ticks fall within the class Arachnida
and constitute 3 families of Parasitiform Acari. Only Argasidae (soft ticks) and Ixodidae (hard ticks) occur in North America. The hard ticks are the most important with regard to human health.
The Tick life cycle has four life stages: egg, larva, nymph and adult. Larvae have 6 legs, nymphs and adults have 8 legs. Adults have a well developed genital plate.
The active stages may be passed on a single host or each stage on a different host. These various associations between active stage and host gives rise to the terms one, two and three host ticks.
19 species of Ticks have been recorded from the Upper Midwest. Ticks are readily identified to genus, even with the immature and often incomplete specimens submitted for identification. Species identification usually requires complete adult specimens. Identification is often easier with female specimens. Because ticks are known disease vectors and individual Ticks may also harbor disease causal organisms for which they are not vectors, proper removal of embedded ticks is important.
Acknowledgements
• This talk has its initial basis in a tick survey of ND ticks conducted by Dr. Don Hyder in 1989‐91. Recent work, Dr. Jeff Vaughn, has added I. scapularis to the ND fauna. Specimen records for the state are from this research and specimens deposited in the North Dakota State Insect Reference Collection (NDSIRC). Sources for images are listed on each slide.
Image sources: (left) http://kirkstarr.vox.com/library/photo/6a00c225264172549d00f48ceedcac0002.html; (right) http://templeofcartoonmojo.blogspot.com/search/label/sketch%20challenge
Useful Literature and references
• Texts.
– Evans, G.O. 1992. Principles of Acarology. CAB International, Cambridge.
– Krantz, G. W. 1978. A manual of Acarology, 2nd ed. Oregon State University Bookstore, Corvalis, OR.
– McDaniel, B. 1979. How to know the mites and ticks. Picture key nature series, Wm. C. Brown Publ. Dubuque, IA. – van der Hammen, L. 1989. An Introduction to Comparative Arachnology. SPB Academic Publishing, The Hague.
Useful Literature and references
• Primary literature.
– Keirans, J. E. and C. M. Clifford. 1979. The genus Ixodes in the United States: a scanning electron microscope study and key to the adults. Journal of Medical Entomology. Supplement 2. 149 pp.
– Keirans, J. E. and T. R. Litwak. 1989, Pictorial key to the adults of hard ticks, Family Ixodidae
(Ixodida: Ixodidae), east of the Mississippi River. Journal of Medical Entomology. 26(5): 435‐ 448.
Useful Literature and references
• Web resources:
– Tree of Life‐ Acari: http://tolweb.org/Acari
– CDC, Tickborne rickettsial diseases: http://www.cdc.gov/ticks/diseases/
– University of Lincoln, UK, Tick genus identification key: http://webpages.lincoln.ac.uk/fruedisueli/FR‐webpages/parasitology/Ticks/TIK/tick‐
key/index_lifestage.htm
– Mites and ticks, a virtual introduction: http://www.sel.barc.usda.gov/acari/index.html
– Discover Life. Acari‐ Ixodidae: http://www.discoverlife.org/mp/20q?search=Ixodidae
– Ticks and animal diseases: http://www.vet.uga.edu/vpp/IVM/ENG/ticks/intro.htm
– Animal and human parasite images: http://www.k‐
state.edu/parasitology/625tutorials/index.html
– University of Rhode Island, Tick encounter resource center:
http://www.tickencounter.org/
– Oak Ridge national laboratory, Tick identification and prevention: http://www.esd.ornl.gov/facilities/nerp/Ticks.pdf
– Iowa State University, Entomological image gallery, ticks: http://www.ent.iastate.edu/imagegal/ticks/