Tick talk: Identification of Ixodidae (Acari) with notes on identification, ecology and phenology. By Dr. Gerald Fauske Department of Entomology North Dakota State University Image sources (left) Blog Lazy Lizard tales http://lazy lizardtales.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 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
Phylum Arthropoda: Jointed legged animals Class Arachnida: Arachnids Phylum Arthropoda: Jointed legged animals Class Arachnida: Arachnids Order Acari: Mites and Tics Image source: Wikipedia http://en.wikipedia.org/wiki/main_page 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: 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. 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 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
Argasidae: Soft ticks Image source: (left) CDC Public Health Library http://phil.cdc.gov/phil/home.asp ; (right) Gary Alpert USDA http://www.forestryimages.org/insects.cfm Scutum present. Mouthparts gnathosoma) visible from above. Scutum absent. 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 Host finding: Haller s organ for long distance host detection. Four segmented palpi for host contact. Host finding Haller s organ. Proximal pit: Chemoreceptors. Distal pit: Humidity sensor. Chemoreceptors sensitive to CO 2 and Butyric acid. Image source: CDC Public Health Library http://phil.cdc.gov/phil/home.asp Image source: (left) Gary Alpert, Harvard http://www.forestryimages.org/insects.cfm ; (right) Uncyclopedia http://uncyclopedia.wikia.com/wiki/uncyclopedia:templates/general
Host finding Palpi. Apical pit: Mechanoreceptors. Chemoreceptors. Hypostome and the feeding process. 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 Feeding process. Adults Adults mate on a host and after another blood meal, eggs develop. Female then leaves host for egg deposition. 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 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
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. Larvae The six legged larva ecloses from the egg and ascends vegetation where it waits for a passing host. 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 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 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. Image source: Penn State University dept of Entomology Image gallery http://www.ento.psu.edu/imagegallery/ticks 1.htm 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 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. 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 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=§ion=medical Image source CDC: http://www.cdc.gov/ncidod/dvbid/lyme/ld_transmission.htm
Tick Anatomy Distinguishing males from females 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 Identification of Tick genera Genus Ixodes Non Ixodes genera: Dermacentor, Amblyoma, Haemaphysalis and Rhipicephalus Ixodes Ixodes scapularis: Black legged tick Anal groove encircling anal plate. No festoons. Basis capituli not angulate Image sources: (top) Animal and Human Parasite organisms, Gary Upton, University of Kansas http://www.kstate.edu/parasitology/625tutorials/in dex.html; (bottom) CDC Public Health Library http://phil.cdc.gov/phil/home.asp Image source: CDC Public Health Library http://phil.cdc.gov/phil/home.asp
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 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. 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 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 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. Species Amblyomma americanum Dermacentor albipictus Dermacentor andersoni Dermacentor variabilis Haemaphysalis leporuspalustris Rhipicephalus sanguineus Common name 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 Amblyomma A. americana: Lone star tick Palpi longer than basis capitulum. 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 Image source Oklahoma State University http://www.ento.okstate.edu/ddd/insects/lonestartick.htm
Identification of Tick genera Haemaphysalis H. leporispalustris: Rabbit tick 2 nd segment of palpus angulate. 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 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 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 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 Texts. Evans, G.O. 1992. Principles of Acarology. CAB International, Cambridge. Krantz, G. W. 1978. A manual of Acarology, 2 nd 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 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/tickkey/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.kstate.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/