In vitro comparative acaricidal efficacy of ivermectin and Metarhizium anisopliae (Hypocreales: Clavicipitaceae) against adult Hyalomma anatolicum ticks (Acari: Ixodidae).

Ticks (Acari: Ixodidae) are the haemotophagous arthropods causing livestock and public health threats. Among various control methods of ticks, chemical control remains the cornerstone especially in the resource-poor communities; however, their extensive or inappropriate use leads to the development of acaricidal resistance. In this regard, efficacy of the commonly used acaricides used in the field must be evaluated and alternate methods should be considered to overcome the prevailing resistance. Thus, the present study was aimed to investigate the acaricidal efficacy of over-the-counter i.e., ivermectin (IVM) in comparison with that of entomopathogenic fungus (EPF); Metarhizium (M.) anisopliae against adults of Hyalomma (H.) anatolicum ticks collected from the selected districts of southern Punjab, Pakistan. The tick specimens appropriately collected in pre-labelled screw-capped plastic bottles, with holes created for aeration, transferred to laboratory for further processing where the ticks were washed and dried over tissue paper. Various doses of the treatments viz.,1%, 1.5%, 2% and 2.5% of IVM and 1×105, 1×106, 1×107 and 1×108 of M. anisopliae were prepared. Sham treatment was made through 1% Triton-X for IVM and 0.1% (v/v) Tween ® 80 for M. anisopliae. A total of 900 partially fed female hard ticks in 10 batches and three repeats were subjected to in vitro Adult Immersion Test (AIT). The best dose of IVM against H. anatolicum was 2.5%, a higher dose, and M. anisopliae gave best results at 1×108. The LC50 (107 spores/ml) and LC90 (108 spores/ml) of M. anisopliae were proved more effective as compared to all IVM concentrations. The results conclude M. anisopliae can be a potential as an augmentative strategy to control hard ticks. However, toxicity trials of M. anisopliae are needed to be done for safety check before their recommendation in the practice. [ABSTRACT FROM AUTHOR]