Harnessing environmental microbiological interventions with micro- and macroorganisms for assessing cattle tick management.

Rhipicephalus microplus, commonly known as the cattle tick, is responsible for causing severe economic losses in livestock production in several countries. The utilization of entomopathogens in infested pastures may represent a sustainable and eco-friendly alternative for tick control. This study evaluated the effectiveness of combining entomopathogenic fungi (EPF, Metarhizium spp.) and entomopathogenic nematodes (EPN, Heterorhabditis bacteriophora) for controlling R. microplus. Laboratory assays tested sub-doses of M. robertsii IP 146 conidia in combination with H. bacteriophora HP88 infective juveniles against engorged females of R. microplus, whereas field trials assessed a granular formulation containing M. robertsii microsclerotia applied with H. bacteriophora infective juveniles in infested field plots to target the tick's non-parasitic phase during rainy and dry seasons. In laboratory experiments, the co-application of fungal sub-doses and nematodes demonstrated synergistic effects, significantly enhancing tick control. Field applications during the rainy season achieved tick population reductions of 54.09% (M. robertsii), 38.11% (H. bacteriophora), and 46.72% (combination). During the dry season, only the fungal formulation significantly reduced tick populations, with 26.27% efficacy. These findings underscore the potential of EPF and EPN, either singly or in combination, as complementary tools to traditional chemical methods for sustainable cattle tick management.