Therapeutic effect of GP543 strain of Bacillus thuringiensis against Amblyomma cajennense ticks in vitro and in naturally infested cattle

• Published in: Parasitology research (1987) 2024-12, Vol.123 (12), p.408-408, Article 408
• Main Authors: Dunstand-Guzmán, Emmanuel, Hallal-Calleros, Claudia, González-Chávez, María Fernanda, Viveros-Rogel, Mónica, Ocampo-Gutiérrez, Ana Yuridia, Peña-Chora, Guadalupe, Flores-Pérez, Fernando Iván
• Format: Article
• Language: English
• Subjects: adults; Amblyomma - microbiology; Amblyomma cajennense; amitraz; Animals; Bacillus thuringiensis; Bacillus thuringiensis - physiology; Biomedical and Life Sciences; Biomedicine; Brief Report; Cattle; Cattle Diseases - drug therapy; Cattle Diseases - parasitology; drugs; ectoparasites; Female; glycerol; Immersion; Immunology; Medical Microbiology; Microbiology; Parasite Load; Parasites; Perineum; Spores, Bacterial - drug effects; surfactants; therapeutics; Tick Infestations - drug therapy; Tick Infestations - parasitology; Tick Infestations - veterinary; Viability
• ISSN: 0932-0113; 1432-1955; 1432-1955
• DOI: 10.1007/s00436-024-08426-4

The current study was focused on evaluating the in vitro effect of the spore-crystal complex of GP543 Bacillus thuringiensis strain on the viability of Amblyomma cajennense , and the in vivo reduction of the parasite load of this ectoparasite on naturally infested cattle. In vitro, 30 adult ticks were treated with 1.2 mg/ml of B. thuringiensis GP543 strain spore-crystal complex in 10 µl/ml of AGREX F® surfactant and 20% glycerin, subjected to the immersion test to assess their viability every 1.5 h up to 6 h and finally at 12 h post-immersion. GP543 was compared to 125 µg/ml of the commercial drug BOMBARD® (amitraz). In vivo, the same concentrations were tested on naturally infested Swiss-Zebu heifers in grazing conditions. Treatments were applied on the perineal region in an area of 30 × 15 cm on days 0 and 7, and the parasite load was determined on days 0, 3, 7, 9, 14, and 21. In vitro, GP543 decreased the viability rate a 96.6% at 12 h post-immersion, while the commercial drug induced a 100% decrease of viability. On heifers, the parasite load decreased after 21 days in the group treated with GP543 in a similar way to the group treated with amitraz. Considering the above, GP543 strain of B. thuringiensis is proposed as a candidate for the control of Amblyomma cajennense .