Amblyomma cajennense
Cayenne tick

Cayenne ticks, Amblyomma cajennense, are distributed over a large portion of the Americas, from the United States to Argentina. They are found throughout much of Central America and the Caribbean Islands. In South America, they are prevalent from the Pacific coast to the Atlantic coasts, extending into southern Chile. Within the United States, cayenne ticks occur in southern and western states, most notably those in the Rocky Mountains. In this region, some ticks of the Family Ixodidae, including cayenne ticks, carry Rocky Mountain spotted fever, a tick-borne disease caused by the bacterium Rickettsia rickettsii. (Oliveira, et al., 2000)

Cayenne ticks are prolific in their choice of habitats and are widely distributed in habitats that contain potential host species. Like other members of Ixodidae, cayenne ticks are commonly found in grassy areas where they may encounter horses, a preferred host. They occasionally occur in wooded areas, where nymphs parasitize various species of birds. (Ogrzewalska, et al., 2009; Oliveira, et al., 2000)

Like other ticks, adult cayenne ticks have two body sections: a fused head and thorax (cephalothorax) and an abdomen (opisthosoma). The cephalothorax contains six pairs of mouthparts and legs, including chelicerae, pedipalps, and four pairs of walking legs. The opisthosoma contains much of the digestive and reproductive systems. Unlike soft ticks, hard ticks (including cayenne ticks) possess a hard shield or body covering known as a scutum and a readily visible head (capitulum) in both the nymph and adult stages. The body of cayenne ticks is mottled brown in color, with a large black region on the abdomen of adult females. Females are much larger than the males. In mating females, the abdomen may grow to many times its original size following feeding, a phenomenon called engorgement.

Cayenne ticks have strong mouth parts used for attachment to the host, along with well developed salivary glands which aid in blood consumption. The chelicerae function as cutting organs for penetration through the host’s skin. All ticks in the genus Amblyomma have relatively long mouth-parts with a well-developed hypostome near the mouth. The hypostome is specially adapted for attachment to the host. This structure is inserted deeply into the host and attached firmly with a glue-like substance secreted from the salivary glands. (Klompen, 2004; Labruna, et al., 2009; Nunes, et al., 2008; Occi, 2008)

Cayenne ticks have 4 developmental stages: egg, larva, nymph, and adult. Females lay numerous eggs in a single egg-laying episode immediately after a large blood meal. Clutch sizes for hard-bodied ticks range from hundreds to 20,000 or more eggs per female. Females die immediately after egg-laying. After eggs hatch, the emerging six-legged larvae lack many of the structures apparent in adults but are capable of feeding. Once larvae have fed, they molt and enter the nymph stage. At this stage, many features of an adult are present, though nymphs are much smaller than adults and are not yet capable of reproduction. Unlike soft-bodied ticks, hard-bodied ticks, including cayenne ticks, have only one nymphal instar. Larval, nymph, and adult cayenne ticks all engage in questing behavior, climbing on vegetation to locate host animals. However, nymphs are less restricted in their feeding behavior and do not specialize on grazing mammals. Instead, nymphs feed on a wide range of available species, with hosts ranging from birds to humans. After another blood meal, nymphs molt and enter the adult stage. Total time of development varies with temperature and availability of hosts. The complete cycle of egg to questing adult usually takes about 6 months. Males significantly outnumber females at all stages of development. (Klompen, 2004; Labruna, et al., 2003; Labruna, et al., 2008; Ogrzewalska, et al., 2009; Oliveira, et al., 2000; Szabo, et al., 2007)

Male cayenne ticks produce pheromones in order to attract females to the host animal on which they are feeding. This ensures that females have the blood meal they require to lay eggs. Fertilization occurs while cayenne ticks are present on a host. Females lay their eggs after an extended gorging period, during which their body swells to roughly 0.6 to 1.0 g. (Labruna, et al., 2003)

Female cayenne ticks lay their eggs about a week following fertilization, generally in spring. They prefer to lay their eggs in areas with extensive vegetation. Eggs hatch in 5 to 7 weeks. Larvae are most prevalent during April and May, though some may be found as late as October. Total time of development varies with temperature and availability of hosts. The complete cycle of egg to questing adult usually lasts about 6 months. (Labruna, et al., 2003; Oliveira, et al., 2000)

Females cayenne ticks die after laying eggs. Males do not take part in the care of eggs or young. Eggs laid during warmer, wetter periods have a better chance of hatching. (Labruna, 2009)

Many species of ticks live for 2 to 4 years. After reproducing, female cayenne ticks die. Reproduction usually occurs within the first year of life. Because cayenne ticks require a blood meal to reproduce, lifespan varies among individuals, particularly with regard to habitat resources. (Klompen, 2004; Labruna, 2009)

Ticks, including cayenne ticks, are obligate ectoparasites, feeding exclusively on blood from vertebrate animals. Unlike many insect parasites, all tick instars are parasitic. Most do not attach permanently to their host, but rather locate a new host for each feeding event.

Like most ticks, cayenne ticks climb grass or other vegetation to search for potential hosts. This behavior is called questing. They climb to different heights depending on the desired host. For example, nymphs, unlike adults, often climb trees to feed on birds.

Once ticks attach to a host organism, they feed until they have grown to many times their original size. Ticks typically feed once per life stage, releasing a host in order to molt between developmental stages. This multiple host behavior leads to a high risk of pathogen spreading, most notably the disease Rocky Mountain spotted fever, which is caused by the bacterium Rickettsia rickettsii. (Klompen, 2004; Labruna, et al., 2008; Ogrzewalska, et al., 2009; Tsunoda, 2007)

Home range sizes are not reported for cayenne ticks. Their range is presumably influenced by the home range of their hosts.

Although they have eyes, eyesight is not well developed in cayenne ticks and is largely restricted to light perception. Cayenne ticks use a variety of other senses to locate host organisms. They rely primarily on temperature and chemical cues. Cayenne ticks have hair-like setae on the body and legs. These are hollow, hair-like structures believed to be used in heat and carbon dioxide perception. Haller's organs sense changes in humidity and have some olfactory function. Chemical receptors known as areae porosae are also present in females. This pair of depressions contains pores and sensory ducts. Males release pheromones to attract females to a host organism on which it is feeding. (Klompen, 2004; Woolley, 1972)

Cayenne ticks feed exclusively on blood from vertebrate animals. Unlike many insect parasites, all tick instars are parasitic. Most do not attach permanently to their host, but rather locate a new host for each feeding event. Cayenne ticks feed on a number of species, including humans, dogs, cattle, horses, donkeys, rabbits, deer and birds. Cayenne ticks feed on fewer of these host species as adults. Although nymphs have little preference in host species, adults often search for equine hosts. (Lopes, et al., 1998; Nunes, et al., 2008; Oliveira, et al., 2000; Szabo, et al., 2004; Szabo, et al., 2007)

Cayenne ticks "quest" to find their host, climbing grass or other vegetation. Hosts can be located tactilely (by touch). Using their setae, cayenne ticks also detect heat and increased levels of carbon dioxide of hosts. Upon locating a host, cayenne ticks attach themselves and burrow into the epidermis, releasing saliva. At this point, any pathogens carried by the tick are released into the host. The saliva contains enzymes which increase blood flow to the area of attachment and prevent clotting. This solution also allows water to be absorbed from the surrounding air and produces enzymes which aid in digestion after blood is ingested. Males preparing to mate may also excrete proteins into the host bloodstream which aid in fertilization of females during mating. The combined effect of this transference of bodily fluids may lead to severe adverse reactions in the host, such as disease, paralysis, immune reactions, or death. Females cayenne ticks consume blood from the host until they become engorged, growing to many times their original size. During this growth, their salivary glands begin to produce granular cells, which are believed to aid in digestion of blood. The glands begin to degenerate two days after engorgement. (Klompen, 2004; Nunes, et al., 2008; Woolley, 1972)

Arthropods, particularly ants, beetles, and spiders, are important predators of ticks, including cayenne ticks. Block noddies feed specifically on cayenne ticks. (Samish and Alekseev, 2001; Samish and Rehacek, 1999)

Populations of ticks appear to be limited by bacteria, fungi, rodents, and birds. Because they have few natural predators, cayenne ticks are not expected to play a major role in ecosystem food chains. As a parasite, however, they may negatively affect their hosts by reducing host vigor via blood loss and especially through transmission of disease. Cayenne ticks are a vector for Rocky Mountain spotted fever, a lethal bacterial disease caused by the bacterium Rickettsia rickettsii. Cayenne ticks feed on a number of species, including humans, dogs, cattle, horses, donkeys, rabbits, deer and birds. (Labruna, et al., 2008; Nunes, et al., 2008; Ogrzewalska, et al., 2009; Oliveira, et al., 2000; Szabo, et al., 2004; Szabo, et al., 2007; Tsunoda, 2007)

The saliva of cayenne ticks is currently being studied for medicinal purposes. It contains a protein known as Factor X Active which may be beneficial in treating blood clots and cancer. (Batista, et al., 2010)

Cayenne ticks act as a vector for Rickettsia rickettsii, the bacterium which causes Rocky Mountain spotted fever. Their effectiveness as a vector stems largely from their indiscriminate selection of hosts during the nymphal stage. Because of their multi-host behavior, the risk of disease transmission is high. The impacts of disease transmission are exacerbated by the large natural range of cayenne ticks. (Labruna, et al., 2003; Labruna, et al., 2008; Lopes, et al., 1998)

Due to the high costs of chemical based tick repellent, research is being conducted on using antigens extracted from cayenne ticks as a means of defending livestock. It has been suggested that goats may develop an immune response to infestations through this process. (Monteiro, et al., 2009)

Cayenne ticks are abundant throughout their range.