Introduction: This study presents for the first time a case of Hyalomma excavatum hyperparasitism and an analysis of this phenomenon in terms of its potential role in the biology of ticks and epidemiology of tick-borne diseases.
Material and methods: Two partially engorged H. excavatum females, one fully engorged female, and 5 males were collected from a naïve rabbit and placed together in a rearing chamber at a temperature of 25°C and 75% humidity.
Results: 3-4 days after tick detachment from the host's skin, one partially engorged H. excavatum female was observed attached to the idiosoma of the fully engorged conspecific female.
Conclusions: This study and observations of other authors confirm that partially engorged ixodid ticks can re-infest the host, and even co-feeding fully engorged ticks in order to collect the blood meal that is indispensable for important physiological processes. However, inefficient feeding of a partially engorged female on another conspecific female may reduce its reproductive performance and disturb the development of eggs and larvae. It seems that parasitism of a tick on another conspecific specimen, when at least one of them is infected by a microorganism, may be a yet poorly explored route of transmission of pathogens or symbionts between the ticks. Initiation of feeding by a hungry or partially engorged tick on a fully engorged specimen is an attempt to obtain food in the drastic conditions of the absence of a target host. Tick hyperparasitism with concurrent pathogen transmission can contribute to the genospecific diversity of pathogens in vectors and hosts.
Keywords: Hyalomma excavatum; hyperparasitism; tick feeding; ticks; transmission of pathogens.