Efficacy of Entomopathogenic fungi against Amblyomma Variegatum Ticks and their control practices in and around Bishoftu, Central Oromia, Ethiopia
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Date
2024
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Addis Abeba University
Abstract
Ticks impact the health of animals and humans and are associated with numerous public health and economic problems around the world. The use of chemical acaricides has been the most commonly used method for tick control on livestock in recent years. However, chemical control of ticks has several disadvantages including high expense, lead to toxic residues in meat and milk, lead to acaricidal resistance and cause environmental pollution. The present in vitro experimental study on the efficacy of entomopathogenic fungi against adult Amblyomma variegatum collected from cattle was conducted from September 2023
to April 2024 in Bishoftu town. The entomopathogenic fungi were isolated from the soil samples in different parts central of Ethiopia. Furthermore, the knowledge, attitudes and practices of the animal owners regarding ticks and tick control was assessed through a structured questionnaire survey. Of the total of 80 soil samples examined for the presence of Entomopathogenic fungi, 17 samples from Bishoftu and Burayu were positive of which Metarhizium anisopliae were detected in 10 soil samples while the rest 7 soil samples were positive for Beauveria bassiana.The working concentrations were prepared from
selected positive isolations at three strength levels (1x10 6 , 1x10 7 and 1x10 8) conidia/ml was applied against Amblyomma variegatum while distilled water and Amitraz 12.5% were used as a negative and positive control, respectively. After applying different concentrations separately, and a mortality rate of 93% and 97.5% was recorded at the concentrations 1x10 7 and 1x10 8 conidia/ml respectively for metarhizium anisoplie and 93.33% and 97% for beauveria issiana after 15 days, with the lowest concentration (1x10 6) conidia/ml showing the lowest death percentage (83.25%) for metarhizium anisoplie and 80.7% for beauveria issiana whereas 76.75% mortality was recorded in the positive control Amitraz. The highest efficacy of Entomopathogenic fungi was observed for the
highest concentration and time in increasing manner. The LC50 of 1 x 10 4 (% 95 CI = 1 x 10 3 - 1 x 10 8) conidia/ml for Metarhizium anisopliae and 1 x 10
4 (% 95 CL = 1 x 10 3–1 x 10 6) conidia/ml for Beauveria bassiana, and LC99 of 1x10 9 (% 95 = 1x10 8-1x10 13 conidia/ml for Metarhizium anisopliae and 1x10 9 (%95=1x10 7-1x10 11) conidia/ml for Beauveria bassiana were recorded using probit regression analysis. This suggests that the EPF have great potential as the alternative approach to chemical acaricides for the control of ticks in Ethiopia.
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Keywords
Amblyomma variegatum, Bishoftu, Burayu Entomopathogenic fungi