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In vitro efficacy of two commercial products of Metarhizium anisopliae s.l. for controlling the cattle tick Rhipicephalus microplus

Eficácia in vitro de dois produtos comerciais de Metarhizium anisopliae s.l. no controle do carrapato bovino Rhipicephalus microplus

Abstract

The effects of two different products - Metarril® SP Organic (dry conidia) and Metarril® SC Organic (emulsifiable concentrated conidia in vegetable oil) - on eggs, larvae and Rhipicephalus microplus engorged females were here explored. Three concentrations (108, 107, and 106 conidia mL-1) for both products were prepared in water + 0.1% Tween® 80 (v/v); afterward, bioassays were carried out for all R. microplus stages by immersion in suspensions (Metarril® SP) or formulations (Metarril® SC). Metarril® SP suspensions showed low efficacy and did not affect biological parameters of treated engorged females; for eggs and larvae, only slight decreases in hatchability and larvae population were observed. Despite a delay in germination, Metarril® SC presented better results; for females, reductions in Egg Mass Weight (EMW) and Egg Production Index (EPI) were reported. On eggs, 108 conidia mL-1 increased Incubation Period (IP), shortened Hatching Period (HP) and decreased hatchability by up to 61%; for larvae, 107 and 108 conidia mL-1 reached 99.6 and 100% larval mortality respectively, 10 days after fungal exposure. Thus, further studies involving the use of oil-based formulations for ticks such as Metarril® SC need to be performed, especially to control the most susceptible stages (eggs and larvae).

Keywords:
Biological control; entomopathogenic fungus; oil-based formulation; cattle tick

Colégio Brasileiro de Parasitologia Veterinária FCAV/UNESP - Departamento de Patologia Veterinária, Via de acesso Prof. Paulo Donato Castellane s/n, Zona Rural, , 14884-900 Jaboticabal - SP, Brasil, Fone: (16) 3209-7100 RAMAL 7934 - Jaboticabal - SP - Brazil
E-mail: cbpv_rbpv.fcav@unesp.br