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Amblyomma maculatumGulf Coast tick

By Sameer Singh

Geographic Range

Ambylomma maculatum can be found over a fairly wide area in the western hemisphere and is considered to be Neotropical and Nearctic. In the United States where it is heavily prevalent they are mainly found in the southern states surrounding the Gulf Coast from Texas to Florida and even up the eastern coast line. This distribution has lead to the tick’s common name of “Gulf Coast tick”. Ambylomma maculutum can also be found in Mexico, Guatemala, Belize, Nicaragua, Honduras, Costa Rica, Columbia, Venezuela, and Ecuador though there is a lack of precise data for exactly where in these countries the ticks are most predominant. (Mangold, et al., 2005; Sumner and Durden, 2007)

Habitat

Adult Amblyomma maculatum spend their time either on the skin of their hosts sucking their blood or on the ground in areas of vegetation. These hosts are fairly non-specific and can include members of the families Equidae, Canidae, and Bovidae as well as some small birds. The tick lives in areas with shrub vegetation and since it is vulnerable to desiccation in areas that do not have enough humidity or too much wind they seek out sheltered areas with good shade cover and relatively high amounts of humidity. (Ketchum, et al., 2005; Mangold, et al., 2005; Teel, et al., 1988)

Physical Description

Adult Amblyomma maculatum varies slightly by gender. Both sexes of the tick have flat eyes and spurs on their fourth coxa that do not quite reach the anus’ level. They also contain a single external spur and an indistinct internal spur on the first coxa. The males have a complete marginal groove between their antennas which the females lack but the females have a glabrous notum but males do not. A comma shaped spiracular plate is seen in both sexes along with a caudal process of the plate which is about half the size of the last festoon. Both the male and female A. maculatum have palpal femurs that double the length of their palpal genu and have chitinous tubercles on the back side of the festoons. While these tubercles are present they are fairly minute and are completely missing on the central festoon. The second to fourth tibia of the ticks have spines and the basis capituli contain laterally produced auriculae and ventral processes. The baisis capituli in these ticks is also fairly straight but contains convex margins in the postero-lateral area.

The larvae of the A. maculatum have broad oval bodies which are widest around the posterior and middle. Covering their bodies are several different pairs of sensilla. For instance, there have four pairs of sensilla sagittiformia as well as several pairs of sensilla hastiformia and sensilla auriformia. The larvae also have many different setae such as the two central dorsal setae, eight pairs of marginal dorsal setae, three pairs of sterna setae, four pre-marginal setae, five marginal ventral setae, one pair of anal setae, and two pre-anal setae. In addition, the A. maculatum larvae have eleven festoons. The cervical grooves on the larvae are nearly parallel but are shallow and extend beyond mid-length before diverging on the larvae’s posterior. The eyes are flat and the first coxa bears a triangular spur while the second and third coxa bear rounded ones. When un-engorged, a sample of these larvae averaged a length of 0.559 mm and an average width of 0.473 mm. (Carleton, et al., 1961; Mangold, et al., 2005; Oliver, 1989; Sumner and Durden, 2007)

  • Sexual Dimorphism
  • sexes colored or patterned differently
  • sexes shaped differently

Development

Amblyomma maculatum is a three host tick. The tick starts life as a larva that parasitizes small birds and then molts into its nymph stage that parasitizes small ground mammals. Finally the tick once again molts into its final adult stage which is sexually active and parasitizes larger mammals. (Ketchum, et al., 2005; Teel, et al., 1988)

Reproduction

There is not much known about the specific way Amblyomma maculatum mates except that the males of the species use pheromones to attract the females for mating on a host. Based off of general ixodid tick behavior, however, it can be assumed that the males and females mate with many partners and that the process probably uses the mouth parts of the male to transfer sperm to the female via a spermatophor. (Oliver, 1989)

In the genus Amblyomma, a female prepares for reproduction by partially engorging herself and then slowing her feeding rate until mating. Mating occurs through the transfer of a spermataphore from the male to the female via the male’s mouth parts and the female’s vagina. Males can mate multiple times, even with the same female. Once a female has she quickly finishes engorging herself to full capacity and drops off the host in order to lay its eggs. The number of eggs depends on the size of the blood meal inside the female. Normally, large Amblyomma species can produce anywhere from 15,000 to 23,000 eggs at a time. Egg production in A. maculatum follows a circadian rhythm. After egg laying the female, like most ixodid tick females, likely dies. (Oliver, 1989)

There isn’t much information specific to the parental investment of Amblyomma maculatum but as a general trend for most of the other ixodid ticks there is no parental investment after the eggs are laid. (Oliver, 1989)

  • Parental Investment
  • pre-fertilization
    • protecting
      • female

Lifespan/Longevity

The specific life span of Amblyomma maculatum is unknown.

Behavior

The primary behavior in all life stages of Amblyomma maculatum is to seek a host through questing, where a tick goes to the top of a plant or leaf and extends its front legs. However, larvae subjected to environments lacking adequate moisture content switched from questing to moisture replenishment. In addition, A. maculatum nymphs will display seasonal increases and decreases in activity during their immature life stages. These increases and decreases vary in timing depending on the tick’s location. For example, A. maculatum nymphs collected in Kansas seem to be more active in the summer months compared to nymphs collected in Texas. The Texas nymphs are generally more active in the winter. These ticks also have a tendency to adapt to a host's grooming habits. For instance, cows infested with A. maculatum rubbed against inanimate objects, and immature ticks responded by spending more of their time moving across the host’s body and attaching to feed for shorter time periods. Finally, A. maculatum nymphs will change molting times in response to photoperiod. (Ketchum, et al., 2005; Lohmeyer, et al., 2009; Sumner and Durden, 2007; Teel and Fleetwood, 1983)

Communication and Perception

The primary form of communication between Amblyomma maculatum adults is through pheromones males use to attract females. To perceive these pheromones as well as to locate hosts A. maculatum, like most ixodid ticks, use a special sensory organ called a Haller’s organ. This organ has many tiny sensory receptors and is used to perceive chemical signals given off by potential hosts. (Chow and Lin, 1972; Gladney, et al., 1974; Nuttall, et al., 1908; Oliver, 1989)

Food Habits

Adult Ambylomma maculatum are parasitic blood feeders and can be found on a wide range of animals. They are moderately host specific and can be found on species of Equidae, Canidae, and Bovidae though they usually prefer larger ungulates. Larval and nymph instars of the tick also suck the blood of their hosts. The larval stage attaches mainly to ground dwelling birds while the nymphs prefer smaller mammals. Humans can be parasitized by this tick. (Ketchum, et al., 2005; Mangold, et al., 2005; Sumner and Durden, 2007; Teel, et al., 1988)

  • Animal Foods
  • blood

Predation

There is no known specific predators on Amblyomma maculatum.

Ecosystem Roles

The biggest impact Amblyomma maculatum ticks have on ecosystems is through their parasitic relationships with ground dwelling birds, small mammals, and large ungulates such as cows. Through the parasitism of such organisms A. maculatum can both lower the overall wellness of its host through blood drinking or by playing a role as a host and vector for various pathogenic parasites like Hepatozoon americanum. (Ketchum, et al., 2005; Mangold, et al., 2005; Mathew, et al., 1999; Teel, et al., 1988)

Species Used as Host
  • Large ungulates
Commensal/Parasitic Species
  • Heptazoon americanum, Rickettsia parkeri

Economic Importance for Humans: Positive

There are no documented economic advantages of Amblyomma maculatum.

Economic Importance for Humans: Negative

The most likely economic damage that Amblyomma maculatum potentially causes are its vectoring of various diseases like Rickettsia parkeri, and Hepatozoon americanum. These diseases can affect people’s ability to work, produce goods, and take time and money to treat. Amblyomma maculatum, a common cattle parasite, can irritate the cows on which they feed. (Ketchum, et al., 2005; Mathew, et al., 1999; Mathew, et al., 2003; Sumner and Durden, 2007)

Conservation Status

Amblyomma maculatum does not have any conservation status.

Contributors

Sameer Singh (author), University of Michigan-Ann Arbor, Heidi Liere (editor), University of Michigan-Ann Arbor, John Marino (editor), University of Michigan-Ann Arbor, Barry OConnor (editor), University of Michigan-Ann Arbor, Renee Mulcrone (editor), Special Projects.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

causes disease in humans

an animal which directly causes disease in humans. For example, diseases caused by infection of filarial nematodes (elephantiasis and river blindness).

causes or carries domestic animal disease

either directly causes, or indirectly transmits, a disease to a domestic animal

chemical

uses smells or other chemicals to communicate

diurnal
  1. active during the day, 2. lasting for one day.
ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

internal fertilization

fertilization takes place within the female's body

metamorphosis

A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

parasite

an organism that obtains nutrients from other organisms in a harmful way that doesn't cause immediate death

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

polarized light

light waves that are oriented in particular direction. For example, light reflected off of water has waves vibrating horizontally. Some animals, such as bees, can detect which way light is polarized and use that information. People cannot, unless they use special equipment.

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

sanguivore

an animal that mainly eats blood

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

semelparous

offspring are all produced in a single group (litter, clutch, etc.), after which the parent usually dies. Semelparous organisms often only live through a single season/year (or other periodic change in conditions) but may live for many seasons. In both cases reproduction occurs as a single investment of energy in offspring, with no future chance for investment in reproduction.

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

visual

uses sight to communicate

References

Carleton, C., G. Anastos, A. Elbl. 1961. The larval ixodid ticks of the Eastern United States. Miscellaneous Publications of the Entomological Society of America, 2/3: 213-237.

Chow, Y., S. Lin. 1972. The musculature and neuromuscular potential in tarsus I of the Gulf Coast tick, Amblyomma maculatum (Acarina: Ixodidae). Annals of the Entomological Society of America, 65/1: 61-64.

Gladney, W., R. Grabbe, S. Ernst, D. Oehler. 1974. The Gulf Coast tick: evidence of a pheromone produced by males. Entomological Society of America, 11/3: 303-306.

Ketchum, H., P. Teel, O. Strey, M. Longnecker. 2005. Feeding predilection of Gulf Coast tick, Amblyomma maculatum Koch, nymphs on cattle. Veterinary Parasitology, 4/5: 349-356.

Lohmeyer, K., J. Pound, J. George. 2009. Effects of photoperiod on reproduction, nymphal developmental timing, and diapause in Amblyomma maculatum (Acari: Ixodidae). Journal of Medical Entomology, 46/6: 1299-1302.

Mangold, A., A. Guglielmone, A. Estrada-pena, J. Venzal, C. Maria. 2005. The Amblyomma maculatum Koch, 1844 (Acari: Ixodidae: Amblyomminae) tick group: diagnostic characters, description of the larva of A. parvitarsum Neumann, 1901, 16S rDNA sequences, distribution and hosts. Systematic Parasitology, 60/2: 99-112. Accessed July 01, 2011 at http://www.springerlink.com/content/l412615472338188/.

Mathew, J., S. Ewing, R. Panciera, K. Kocan. 1999. Sporogonic development of Hepatozoon americanum (Apicomplexa) in its definitive host, Amblyomma maculatum (Acarina). The Journal of Parasitology, 85/6: 1023-1031. Accessed July 01, 2011 at http://www.jstor.org/stable/3285663.

Mathew, J., V. Shkap, D. Macintire, J. Barta, S. Ewing. 2003. Canine hepatozoonosis: two disease syndromes caused by separate Hepatozoon spp. Trends in Parasitology, 19/1: 27-31.

Nuttall, F., W. Cooper, L. Robinson. 1908. On the structure of "Haller's Organ" in the Ixodoidea. Parasitology, 1/3: 238-242.

Oliver, J. 1989. Biology and systematics of ticks (Acari: Ixodida). Annual Review of Ecological Systems, 20: 397-430.

Sumner, J., L. Durden. 2007. Gulf Coast ticks (Amblyomma maculatum) and Rickettsia pareri, United States. Emerging Infectious Diseases, 13/5: 751-753.

Teel, P., S. Fleetwood. 1983. Variation in activity of ageing Amblyomma maculatum Koch (Acarina: Ixodidae) larvae in relation to vapor presssure deficits in pasture vegetation complexes. Prot. Ecol., 5/4: 343-352.

Teel, P., C. Scifres, T. Oldham, L. Drawe. 1988. Gulf Coast tick (Amblyomma maculatum) populations and responses to burning of coastal prairie habitats. The Southwestern Naturalist, 33/1: 55-64.

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