The aim of the present study was to analyze ten native Metarhizium spp. isolates as to their UV‐B tolerances. Comparisons included: different fungal propagules (conidia, blastospores, or microsclerotia [MS]); conidia in aqueous suspensions or in 10% mineral oil‐in‐water emulsions; and conidia mixed with different types of soil. The UV‐B effect was expressed as the germination of conidia or culturability of blastospores and MS relative to nongerminated propagules. Metarhizium anisopliae LCM S05 exhibited high tolerance as blastospores and/or MS, but not as conidia; LCM S10 and LCM S08 had positive results with MS or conidia but not blastospores. The formulations with 10% mineral oil did not always protect Metarhizium conidia against UV‐B. Conidia of LCM S07, LCM S08, and LCM S10 exhibited the best results when in aqueous suspensions, 24 h after UV‐B exposure. In general, conidia mixed with soil and exposed to UV‐B yielded similar number of colony forming units as conidia from unexposed soil, regardless the soil type. It was not possible to predict which type of propagule would be the most UV‐B tolerant for each fungal isolate; in conclusion, many formulations and propagule types should be investigated early in the development of new fungal biocontrol products.

The chemical composition of tick cuticles acts as a barrier to pathogens and may limit infection by entomopathogenic fungi. This study characterized the cuticular neutral lipids (NL) and hydrocarbons (HCs) of four ixodid ticks that are widely distributed in Brazil. HC extracts were analyzed by gas chromatography-mass spectrometry and used to challenge Beauveria bassiana IP361 and Metarhizium robertsii IP146; the effect of cuticular extracts in fungal growth were evaluated by disk diffusion and conidial viability assays. In addition, conidial germination on the tick cuticle was evaluated by scanning electron microscopy, and NL from ticks treated with fungi were assessed by thin layer chromatography. Six HCs were exclusively identified in Amblyomma sculptum. Additionally, cuticle extracts from Dermacentor nitens and A. sculptum inhibited the growth of M. robertsii IP146 and reduced conidial germination of B. bassiana IP361 to 70% and 49%, respectively; the same extracts also produced cytotoxic effects, with conidial death above 30% and 60%. Electron micrographs showed a delayed germination of conidia incubated for 48 h or 72 h on D. nitens and A. sculptum. The lipid profile of A. sculptum treated with fungi was not significantly altered; triacylglycerol was not detected in the cuticle extracts of any other tick species. Finally, A. sculptum and D. nitens cuticles have lipid components that may limit the development of M. robertsii.

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.

BACKGROUND: The cattle tick Rhipicephalus microplus is a major constraint to livestock production in tropical regions, causing substantial economic losses and driving intensive acaricide use. Despite its importance, the role of pasture composition in shaping off‐host tick populations remains poorly understood. This study evaluated whether forage grass species create distinct microenvironments that influence the seasonal abundance and persistence of R. microplus larvae in a tropical region. RESULTS: Larval abundance was higher overall in the dry season than in the rainy season, with a significant interaction between grass and season. Grass cultivars differed markedly during the dry season. Two Megathyrsus maximus cultivars supported the highest larval densities and the longest recovery windows, whereas two Urochloa sp. cultivars showed the lowest larval densities. Differences in larval abundance were not significant during the rainy season across grasses ( P = 0.13). Minimum temperature and minimum relative humidity were the most influential microclimatic predictors of larval abundance. CONCLUSION: The interaction between forage species and seasonal climate influences R. microplus population dynamics, particularly under dry conditions. Although pasture composition alone is unlikely to determine infestation levels under grazing conditions, and larval abundance in pasture does not necessarily translate directly into infestation levels on cattle, certain grass cultivars may contribute to microenvironments less favorable for tick survival. These findings highlight the potential of forage species to influence off‐host tick dynamics, acting as a complementary component of the integrated R. microplus management. © 2026 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Anti-tick vaccines represent a promising alternative to chemical acaricides for the management of ticks on wildlife; however little progress has been made to produce a vaccine effective in wild hosts that are critical for tick reproduction, such as the white-tailed deer ( Odocoileus virginianus ; WTD). To date, most tick antigens have been tested using laboratory models (i.e. rabbits); however, their expression in wild hosts has not been confirmed. We recently tested Amblyomma americanum salivary (SG) and midgut (MG) extracellular vesicles (EVs) as vaccine candidates in WTD, which resulted in on-host female tick mortality. Using a proteomic approach, we show that these SG- and MG-EVs contain a “core-cargo” enriched in chaperones, small GTPases, actin and actin-related proteins, and other proteins previously reported in small EVs. Label-free quantitative proteomics showed significant differences in protein cargo between MG and SG-EVs (333 proteins out of 516). Pre-vaccinated and day 57 post-injection serum samples from three vaccinated and one control WTD were used to immuno-precipitate antigenic proteins from SG- and MG-EV preparations. Proteomic analysis of immunoprecipitated proteins identified thirty antigens with potential for use in anti-tick vaccines, seven of which we have categorized as high priority. These proteins represent promising candidates for anti-tick vaccine design in WTD and other wildlife hosts.