The Cayenne tick (Amblyomma mixtum – formerly Amblyomma cajennense) is a cold-sensitive species, active year-round in tropical and sub-tropical areas of the Caribbean and Mexico, extending southward throughout much of Central and South America. Populations within the US are confined primarily to south Texas, although collections of Cayenne ticks from Florida and coastal regions of other states bordering the Gulf of Mexico have been reported.
Adult Cayenne ticks have among the longest mouthparts of all native Amblyomma species. Unfed ticks are similar in aggressiveness and overall appearance to Lone
Star ticks, but female Cayenne ticks lack the white dorsal spot and are uniformly dark brown in color and present a tan colored scutum, overlaid by a dark brown ornation pattern resembling a pendant necklace.
Females are generally larger than males, averaging 2–6 mm unfed, and 10-15 mm or larger once fully fed. Male ticks average 2–5 mm regardless of feeding duration. Scutum coloration of males ranges tan to golden-beige, often with rust-colored patches amid dark-brown mottled striations.
Cayenne ticks have 3 life stages: 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.
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.
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. 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.
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.
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.
Cayenne ticks feed exclusively on blood from vertebrate animals. 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.
As with most other ticks, Cayenne ticks “quest” to find their host, climbing grass or other vegetation and extend their front two legs to hitch a ride on a passer-by. Hosts can be located tactilely (by touch); but also by 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.
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.
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.
Lab studies show that the Cayenne tick may also be capable of transmitting an Equine Piroplasmosis, called Theileria equi however this is still being studied and results are inconclusive.
Cayenne ticks are prolific in their choice of habitats and are widely distributed in habitats that contain potential host species. Like other hard-bodied ticks, 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.
Cayenne ticks are commonly found from Texas to the western areas of Ecuador. Amblyomma mixtum is a cold-sensitive species that is active year-round in tropical and sub-tropical areas of the Caribbean and Mexico. Populations within the US are primarily confined to south Texas, although collections of Cayenne ticks from Florida and coastal regions of other states bordering the Gulf of Mexico have been reported.
The American Dog Tick occurs primarily in wooded, shrubby and long-grass areas. However, it is possible for residential areas to support populations of this tick. Shrubs, weeds, tall grass, clutter and debris on the property attracts the rodents that are hosts for immature ticks. By maintaining grass short, removing possible rodent harborage, and sealing cracks and crevices in and around the property one can directly reduce or prevent local tick populations.
Keeping grass and weeds cut short decreases humidity, which helps kill ticks or makes an area undesirable for ticks and rodents. Additionally, it makes it difficult for ticks to climb on the vegetation and wait for its host. If pesticides are applied, cutting the vegetation short increases effectiveness and allows for better coverage. Removing rodent harborage areas may reduce an infestation.
Because dogs can easily pick up ticks while walking on infested grass or roaming through wooded areas, it is necessary to treat the pet properly. There are many products that can be applied to prevent or treat a tick infestation on an animal including topical treatments and sprays. Regularly grooming, washing bedding, and examining the dog are strongly recommended to prevent tick infestations.