Observations on the Biology of the Ixodidae. Part III. Dealing with the behaviour of the sexes in Amblyomma hebraeum, Hyalomma aegyptium and Rhipicephalus bursa when upon the host
Authors: Nuttall George H. F. 
Published: June 2009

Amblyomma hebraeum males anchor immediately when placed in a hungry state upon the host. The females will not do so as a rule in the absence of previously anchored males. Usually the males do not move or scarcely move when once anchored on the host, they may continue to remain attached to the host for months after the females have dropped off gorged. The males, after having fed for a few days, show signs of sexual excitement in that they erect their bodies away from the host and extend their legs, whereby, without releasing their mouthparts from the host's skin, they seize and hold any females that chance their way. The males become excited when the skin of the host in their vicinity is handled, no females having been near them for months. To copulate, the males must necessarily release their mouthparts, and this may at times lead to their shifting their position. They may occasionally shift to a fresh anchorage in company with their females, or they may shift a few mm. when apparently alone. A male may copulate with several females. The coloration of the male changes after prolonged sojourn upon the host (77–141 days).

After feeding for 2–8 days or more, the females wander and are grasped by anchored males so that the ticks' ventral surfaces are apposed, and in this position the female proceeds to feed with her mouthparts puncturing the skin of the host in close proximity to those of the male. Copulation takes place in due course, the male temporarily removing his mouthparts from the host for the purpose. A female may seek two males in succession but usually one male appears to suffice. Females feed very slowly in the absence of males, they gorge rapidly when fertilized, and, when fully gorged, usually abandon the host without delay. Depending upon their having access to males and access to a more or less adequate food supply from the host, the females remain upon the host for 4–25 days before dropping off in a gorged condition.

Hyalomma aegyptium males anchor immediately when placed upon the host. In the absence of females they remain fixed or change their position but slightly at long intervals of time. When hungry males and females are placed together upon the host, they proceed to suck blood at once, and, after a preliminary feed lasting five or more days, the males wander in search of females. A male may copulate with several females. Females placed in close proximity to males cause these to become excited (as in A. hebraeum). The females as a rule do not change their anchorage upon the host from start to finish, being sought by the males. The latter stay upon the host indefinitely (122 or more days) after the gorged and fertilized females have dropped off.

Rhipicephalus bursa males and females, when hungry, proceed to feed at once when placed together upon the host. After remaining fixed for 3–5 days, the males seek anchored females. The males may seek a number of females in succession, usually feeding for some days prior to seeking a fresh female. Males continue to wander from anchorage to anchorage in the absence of females, they may thus wander about for 86 days or longer after the females have abandoned the host. A male may copulate with several females.

The behaviour of the sexes differs therefore in the three foregoing species. In A. hebraeum the females seek the males, in H. aegyptium and R. bursa the males seek the females. In all three species the males remain upon the host indefinitely after the females have dropped off. In R. bursa the males continue to wander about from anchorage to anchorage long after the females have left, whilst in A. hebraeum and H. aegyptium the males stop their wandering entirely or shift but slightly at longer intervals of time.

The predominance of male ticks of any species upon a host under natural conditions is accounted for by their staying on and accumulating upon the host whilst successive lots of females drop off. As an example I may mention that I have seen camels in Biskra on which only males of H. aegyptium could be found; these males must have been a very long time upon the camels because their scutums were polished and scratched, the rugose surface so characteristic of the young male tick having been worn away.

Copulation in all three species was observed on several occasions upon the host, the process lasted 10 minutes or longer and was similar to that described by me for Ornithodorus and Ixodes.

Since the liability to injury increases with the degree of engorgement of the female tick it is a great safeguard to her that she attains her full state of engorgement rapidly at the end of her feeding period and that she drops from the host promptly.