Corn oil-formulated Cordyceps javanica: a high-performance, low-impact tool for integrated tick management

Mycoacaricides represent a promising alternative for managing resistant tick populations. This study evaluated the efficacy of corn oil-based Cordyceps javanica formulations against non-parasitic stages the southern cattle tick Rhipicephalus microplus under laboratory and semi-field conditions. Additionally, fungal persistence in soil and possible alterations in soil composition were assessed using ATR-FTIR spectroscopy combined with chemometric analysis. Corn oil (1%, 3%, and 5%) combined with 0.01% silicone oil did not affect conidial germination (> 98.4%). Corn oil and C. javanica suspensions alone yielded larval average mortality of 20.1% and 18.8%, respectively, 15 days after the treatment. When formulated in corn oil, averages of larval mortality ranging from 64.1% on day 5 to 100% on day 15, indicating a synergistic effect between fungus and oil. Corn oil alone resulted in a female tick control percent ranged from 20.5 to 73.3%, while the fungus alone achieved 28.2% and 14.9% control at 10⁷ and 10⁸ conidia/mL, respectively. All fungus-oil formulations significantly reduced female reproductive efficiency, achieving 90-100% tick control. Under semi-field conditions, the 10⁸ conidia/mL + 3% corn oil formulation reduced larval recovery from Urochloa decumbens pots by 98.6% compared to the oil and silicone control. Thirty days after application, C. javanica persisted in soil at 2.1 ± 0.3 × 10⁵ CFU/g (39.4% recovery). ATR-FTIR analysis showed no detectable alterations in the soil's chemical profile following application of any formulation. These results highlight the potential of oil-based C. javanica formulations as an effective and sustainable tool for integrated tick management in livestock systems.