The increasing global burden of mosquito-borne diseases and the widespread development of insecticide resistance in mosquitoes have fueled renewed interest in entomopathogenic fungi as effective tools that are compatible with existing mosquito control strategies. These fungi produce different types of infective propagules, including hydrophobic conidia and yeast-like blastospores, which differ in structure, mode of infection, and virulence. In this study, we evaluated the larvicidal activity of conidial and blastospore propagules from Beauveria bassiana MBC076 and Beauveria brongniartii MBC397 against Aedes aegypti. Conidia exhibited more rapid and more potent larvicidal effects compared to blastospores, but the overall survival at seven days post-infection was similar between the two types of propagules. Interestingly, B. brongniartii blastospore infections resulted in a significantly higher proportion of pupal mortality, suggesting a delayed mode of action. Immune profiling of infected larvae indicated significant induction of antimicrobial effectors such as cecropin, defensin, and attacin, primarily in response to conidial infection. In contrast, blastospore infections were associated with reduced expression of several prophenoloxidase genes, particularly during infection with B. brongniartii blastospores. These findings indicate that different fungal species and their propagule types exert varying levels of virulence and immune modulation in mosquito larvae. This study provides insights into the infection dynamics of fungal propagules and identifies immune markers that can be leveraged to enhance the efficacy of fungal-based larvicides.

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.