Biology and ecology of the brown dog tick, Rhipicephalus sanguineus

Abstract

The brown dog tick (Rhipicephalus sanguineus) is the most widespread tick in the world and a well-recognized vector of many pathogens affecting dogs and occasionally humans. This tick can be found on dogs living in both urban and rural areas, being highly adapted to live within human dwellings and being active throughout the year not only in tropical and subtropical regions, but also in some temperate areas. Depending on factors such as climate and host availability, Rh. sanguineus can complete up to four generations per year. Recent studies have demonstrated that ticks exposed to high temperatures attach and feed on humans and rabbits more rapidly. This observation suggests that the risk of human parasitism by Rh. sanguineus could increase in areas experiencing warmer and/or longer summers, consequently increasing the risk of transmission of zoonotic agents (e.g., Rickettsia conorii and Rickettsia rickettsii). In the present article, some aspects of the biology and ecology of Rh. sanguineus ticks are discussed including the possible impact of current climate changes on populations of this tick around the world.

Figure 1

Immature and adult stages of Rhipicephalus sanguineus. A: larva (mounted in Hoyer's medium; bar = 400 μm). B: nymph (mounted in Hoyer's medium; bar = 0.5 mm). C: female (bar = 1 mm). D: male (bar = 1 mm).

Figure 2

Attachment sites of Rhipicephalus sanguineus. A: three adults on the ear of a dog. B: two females attached to the axilla of a dog. C: an engorged nymph on the interdigital region of a dog.

Figure 3

Tick mouthparts. A: Ixodes ricinus nymph (bar = 200 μm). B: Rhipicephalus sanguineus nymph (bar = 250 μm). Note the rostrum of Rh. sanguineus (wider than long) in comparison with the one of I. ricinus (twice longer than wide).

Figure 4

Attachment of Rhipicephalus sanguineus. A: A male firmly attached to the dog's skin. Note that while the tick is being gently pulled with the help of a tweezers, the skin is stretched out. B: A female exhibiting a piece of a dog's skin that remained attached to her mouthparts after her forced removal.

Figure 5

Mating of Rhipicephalus sanguineus. A: A couple of Rh. sanguineus mating on a dog (the male is arrowed). B: A spermatophore attached to the female genital aperture (bar = 600 μm).

Figure 6

Oviposition of Rhipicephalus sanguineus. A: Several females laying eggs under laboratory conditions (temperature 26°C, relative humidity, 80%). B: A close-up of the previous image, showing in detail the newly laid eggs.

Figure 7

Moulting of Rhipicephalus sanguineus. A: A nymph (arrow) emerging from its larval exuvia. B: An engorged nymph (few hours prior the ecydisis), exhibiting the short, anterior dorsal scutum (ds) and the alloscutum (as) of a typical female. A nymphal exuvia (arrow) left behind by other female can be seen as well.

Figure 8

Hiding-places of Rhipicephalus sanguineus. A: A fully engorged female walking on a limestone wall. B and C: Engorged females (arrows) hidden in cracks of the same wall. D: Several engorged females on the ground between rocks.