Hyalomma scupense (Acari, Ixodidae) in northeast Tunisia: seasonal population dynamics of nymphs and adults on field cattle

Hyalomma scupense is a two-host tick infesting mainly cattle representing in North Africa the vector of tropical theileriosis (Theileria annulata infection), a major tick-borne disease affecting cattle. Any effective control programme of ticks requires a good knowledge of the biology of the target species. In the present study, three cattle farms in northeast Tunisia were surveyed during the activity seasons for adult and nymphs of Hyalomma scupense. Several indicators were studied, including chronological indicators, infestation prevalence, infestation intensity and feeding predilection sites of the ticks. The adult ticks were present from mid-June to late November. Nymphs were observed on animals from early September to late November. A large proportion of the ticks were attached in the posterior udder quarters: 41% and 64% of adult ticks and nymphs, respectively. The animals that were heavily infested by adult ticks were also heavily infested by nymphs. Moreover, 17% of adult ticks and 53% of nymphs were present on only 5% of cattle population. These data are important for the success of targeted acaricide application leading to a dramatic decrease of acaricide quantity needed for the treatment. When the preferential sites of attachment are known, the effectiveness of manual removal of ticks can be improved. The presence of highly infested animals is to be considered when any control programme is implemented, since these animals harbour a high proportion of the ticks. Hyalomma scupense est une tique diphasique qui infeste principalement les bovins, elle représente en Afrique du Nord le vecteur de la theilériose tropicale du bœuf (infection par Theileria annulata), une maladie majeure transmise par les tiques affectant les bovins. Tout programme de contrôle des tiques nécessite une connaissance solide de la biologie de la tique cible. Dans le présent travail, trois élevages bovins au Nord-Est de la Tunisie ont été suivis durant la saison d’activité des adultes et des nymphes de Hyalomma scupense. Plusieurs indicateurs ont été étudiés, dont les indicateurs chronologiques, la prévalence d’infestation, l’intensité d’infestation et les sites de prédilection des tiques. Les tiques adultes étaient présentes entre mi-juin et fin novembre. Les nymphes ont été observées sur les animaux dès le début de septembre jusqu’à fin novembre. Une large proportion des tiques était attachée aux quartiers postérieurs des mamelles avec respectivement 41 % des adultes et 64 % d