Inventory and distribution of hard ticks (Ixodidae), ectoparasites of cattle and domestic dogs, in the Djelfa region, search for pathogens in the Rhipicephalus sanguineus species, and control trials

Abstract

This study presents an integrated investigation of hard tick populations and their associated microbial communities in the Djelfa region, with particular emphasis on Hyalomma excavatum and Rhipicephalus sanguineus. The research is organized into four main sections : The first section provides a spatiotemporal inventory of hard ticks collected from domestic dogs (two localities) and cattle (one locality) over the course of one year. A total of 8,405 ticks were identified. Rhipicephalus sanguineus was the predominant species in dogs, while Hyalomma excavatum dominated in cattle. Pronounced seasonal variations were observed, with infestation rates peaking in summer. Differences in species composition, sex ratios, and ecological indices between sites underscored the influence of environmental and host-related factors.The second section focuses on pathogen interactions in Hyalomma excavatum. Species identification was confirmed through morphological analysis and 16S rRNA gene sequencing. Pathogen screening revealed a high prevalence of Rickettsia spp., with sex-specific patterns: higher coinfection rates in females and simpler infection profiles in males. Network analyses showed that both sex and seasonal shifts significantly shaped pathogen interaction structures, with Francisella-like endosymbionts playing a central role in maintaining network integrity, especially during summer. The third section explores the microbiome dynamics of Hyalomma excavatum across spring, summer, and autumn. While alpha diversity remained stable, beta diversity analyses revealed distinct seasonal clustering of microbial communities. Marked seasonal changes were observed in the relative abundance of key microbial taxa, including Francisella, Candidatus, and Midichloria. Network robustness analyses indicated that Francisella contributed significantly to microbial community cohesion during summer, while Rickettsia played a greater role in network connectivity in autumn. The fourth section evaluates the acaricidal activity of essential oils extracted from three medicinal plants: Artemisia herba alba (48.84% Davanone), Rosmarinus officinalis (43.52% Camphor) and Thymus vulgaris (18.3% Carvacrol). Thymus vulgaris oil exhibited the highest efficacy, achieving 100% larval mortality and 90% egg hatch inhibition at 5 µl/ml within 72 hours. The estimated LD90 values after 72 hours were 2.990 µl/ml for Artemisia herba alba, 3.783 for Rosmarinus officinalis, and 2.677 for Thymus vulgaris. Statistical analysis confirmed significant dose-dependent efficacy for all tested oils, highlighting Thymus vulgaris as a promising candidate for eco-friendly tick control. Altogether, this study offers novel insights into tick ecology, pathogen–microbiome interactions, and environmentally sustainable control strategies, contributing valuable knowledge toward improved management of tick-borne diseases in semi-arid regions.