Publication Type
Journal Article
Journal Name
Veterinary Parasitology
Publication Date
7-30-2016
Abstract
Rhipicephalus decoloratus causes serious economic losses in cattle industry every year in East Africa. Biological control using entomopathogenic fungi is seen as a promising alternative to chemical acaricides being used for their control. The pathogenicity of Metarhizium anisopliae and of Beauveria bassiana isolates was tested in the laboratory against amitraz-resistant and amitraz-susceptible strains of R. decoloratus. Unfed larvae were sprayed with conidial suspensions of 1 × 109 conidia ml-1. Fungal isolates were pathogenic to R. decoloratus larvae, causing mortality of between 10.0 and 100% and between 12.1 and 100% of amitraz-susceptible and amitraz-resistant strains, respectively. The LT50 values of selected fungal isolates varied between 2.6-4.2 days in amitraz-susceptible strain and between 2.8-3.9 days in amitraz-resistant strain. The LC50 values varied between 0.4 ± 0.1 and 200.0 ± 60 × 103 conidia ml-1 and between 0.1 ± 0.1 and 200.0 ± 31.0 × 103 conidia ml-1 in amitraz-susceptible and amitraz-resistant strains, respectively. Metarhizium anisopliae isolate ICIPE 7 outperformed the other isolates and was selected for compatibility study with amitraz and field trial. ICIPE 7 was compatible with amitraz. In the field, four treatments including control, ICIPE 7 alone, amitraz alone and ICIPE 7/amitraz were applied on cattle. All the treatments significantly reduced the number of ticks on all the sampling dates: day 7 (F3,8 = 3.917; P = 0.0284), day 14 (F3,8 = 9.090; P = 0.0275), day 21 (F3,8 = 37.971; P = 0.0001) and day 28 (F3,8 = 8.170; P = 0.0016) compared to the control. Results of the present study indicate that ICIPE 7 can be used for the management of amitraz-resistant strain of R. decoloratus.
Keywords
Acaricide, Beauveria bassiana, Biocontrol, Metarhizium anisopliae, Rhipicephalus decoloratus, Tick
Disciplines
Environmental Sciences
PubMed ID
27369570
Recommended Citation
Murigu, M., Nana, P., Waruiru, R., Nga'nga', C., Ekesi, S., & Maniania, N. (2016). Laboratory and field evaluation of entomopathogenic fungi for the control of amitraz-resistant and susceptible strains of Rhipicephalus decoloratus. Veterinary Parasitology, 225, 12-18. https://doi.org/10.1016/j.vetpar.2016.05.026
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