Potencial de fungos entomopatogênicos no controle de Raoiella indica (HIRST, 1924) (acari: tenuipalpidae)

Abstract

Infestations of Raoiella indica Hirst (1924) (Acari: Tenuipalpidae), an invasive mite with remarkable ecological adaptability, have emerged as one of the main phytosanitary challenges in tropical agroecosystems, severely affecting crops of high economic importance. The use of entomopathogenic fungi-based biopesticides has shown promise as an alternative strategy for managing this pest, especially given the limitations and environmental concerns associated with the continued use of synthetic acaricides. This study aimed to evaluate the pathogenicity of Beauveria bassiana and Metarhizium anisopliae against adult females of R. indica under laboratory conditions, and to estimate the lethal concentrations (LC50 and LC90) of the most effective isolate. The isolates used were obtained from commercial formulations: IBCB66 (B. bassiana, Vittia®), CBMAI1306 (B. bassiana, Dillon®), BEAU CNV (B. bassiana, Agrinor®), and a multistrain formulation composed of IBCB66 + IBCB425 (B. bassiana + M. anisopliae, Dillon®).Fungal suspensions at the highest concentrations recommended by the manufacturers (108 conidia/mL) were applied using a Potter spray tower onto arenas containing R. indica females, and daily mortality was recorded for seven days to determine lethal time (LT). Lethal concentrations were estimated from serial dilutions (108, 107, 106, 105, 104, 103, and 102 conidia/mL). Data were analyzed using Probit regression to determine lethal dose parameters. The BEAU CNV isolate (Agrinor®) was the most virulent compared to the four tested strains, exhibiting an LT50 of 0.90 days and LT90 of 2.12 days. The estimated LC50 was 2.8 × 104 conidia/mL, while the LC90 was 1.73 × 106 conidia/mL—values considered effective and technically feasible for practical use. These findings highlight the high potential of the BEAU CNV isolate for the biological control of R. indica, reinforcing its suitability for integration into pest management programs.