In-vitro Studies on Efficacy of Native Entomopathogenic Nematodes (Steinernema carpocapsae) on Cattle Ticks Subhash Kachhawaha 1* Ajay Kumar Maru 2 and A.U. Siddiqui 3 1 KVK, ICAR-Central Arid Zone Research Institute, Jodhpur 342 003, India 2 Department of Nematology, B.A. College of Agriculture, A.A.U., Anand xxx xxx, India 3 Department of Nematology, R.C.A., M.P.U.A.T., Udaipur xxx xxx, India Received: Abstract: Entomopathogenic nematodes (EPNs) have been successfully used as biological control agents for insects of economically important crops. In the present study, bio-efficacy of two different strains of entomopathogenic nematodes, Steinernema carpocapsae STSLU and S. carpocapsae STUDR against two different cattle hard ticks, Rhipicephalus microplus and Hyalomma savignyi was evaluated based on percentage mortality under laboratory conditions. The adult female cattle ticks (of both species) were treated with infective juveniles (IJs) of both the strains of S. carpocapsae at different inoculum levels. All the treatments were replicated four times at 20ºC. Percentage mortality of the cattle ticks was determined every 24 hours up to 120 hours from the time of inoculation. The experimental results showed the cattle tick R. microplus was more susceptible to both strains of Steinernema carpocapsae than that of H. savignyi. Further, S. carpocapsae STSLU was more efficient than S. carpocapsae STUDR and caused 100 and 97.5% mortality of R. microplus and H. savignyi, respectively at a concentration of 250 IJs Petri dish -1 after 120 hours of inoculation. The entomopathogenic nematodes can be cultured easily in an artificial medium and have high reproductive efficiency, broad host range, long storage ability, ease of application and being safe for the host make them promising bio-control agent against R. microplus and H. savignyi. This may be evaluated further in field conditions in different seasons and temperatures. Future research may be directed towards emerging technologies of ticks control without acaricide uses. Keywords: Ticks, biological control, entomopathogenic nematodes, Steinernema carpocapsae, Rhipicephalus microplus, Hyalomma savignyi Ticks can be found on many hosts, including cattle, buffalo, horses, donkeys, goats, sheep, deer, pigs, dogs and wild animals. Ticks are one of the leading monetary menaces to the cattle industry worldwide, affecting productivity, health and welfare. They are obligate blood-feeding ectoparasites Annals of Arid Zone 62(3): 1-6, 2023 https://epubs.icar.org.in/index.php/AAZ OPEN ACCESS Edited by Praveen Kumar Vipin Choudhary K.S. Jadon R.K. Solanki *Correspondence Subhash Kachhawaha drsubhashcazri@gmail.com Citation Kachhawaha, S., Maru, A.K. and Siddiqui, A.U. 2023. In-vitro studies on efficacy of native entomopathogenic nematodes (Steinernema carpocapsae) on cattle ticks. Annals of Arid Zone 62(3): https://doi.org/10.59512/aaz.2023.62.3.10 https://epubs.icar.org.in/index.php/AAZ/ article/view/136727