Modified Adamek's medium renders high yields of Metarhizium robertsii blastospores that are desiccation tolerant and infective to cattle-tick larvae

Author(s)

Iwanicki, Natasha Sant'Anna ^[1] ; Ferreira, Bruna de Oliveira ^[1] ; Mascarin, Gabriel Moura ^[2] ; Delalibera Junior, Italo ^[1]

Affiliation

^[1] Univ Sao Paulo, ESALQ, Dept Entomol & Acarol, Av Padua Dias 11, CP 9, BR-13418900 Piracicaba, SP - Brazil

^[2] Embrapa Meio Ambiente, Rodovia SP-340, Km 127-5 S-N, BR-13820000 Jaguariuna, SP - Brazil

• Document type: Journal article
• Source: FUNGAL BIOLOGY; v. 122, n. 9, p. 883-890, SEP 2018.
• Web of Science Citations: 0

Abstract

Blastospores are yeast-like cells produced by entomopathogenic fungi that are infective to arthropods. The economical feasible production of blastospores of the insect killing fungus Metarhizium spp. must be optimized to increase yields. Moreover, stabilization process is imperative for blastospore formulation as a final product. In this sense, our goal was to increase blastospore production of two Metarhizium isolates (ESALQ1426 and ESALQ4676) in submerged liquid cultures. A modified Adamek's medium was supplemented with increased glucose concentrations and the fermentation time was accelerated by using a blastospore pre-culture as inoculum. Virulence of air-dried stable blastospores was compared with conidia toward larvae of the cattle tick, Rhipicephalus microplus. Our results revealed that blastospore production of Metarhizium is isolate- and species-dependent. Glucose-enriched cultures (140 g glucose/L) inoculated with pre-cultures improved yields with optimal growth conditions attained for Metarhizium robertsii ESALQ1426 that rendered as high as 5.9 x 10(8) blastospores/mL within 2 d. Resultant air-dried blastospores of ESALQ1426 were firstly proved to infect and quickly kill cattle tick larvae with comparable efficiency to conidia. Altogether, we argue that both osmotic pressure, induced by high glucose titers, and isolate selection are critical to produce high yields of blastospores that hold promise to control cattle-tick larvae. (C) 2018 British Mycological Society. Published by Elsevier Ltd. All rights reserved. (AU)

• FAPESP's process: 16/20610-6 - Advances in Metarhzium blastospores production and formulation and transcriptome study of metacyclic yeast growth
• Grantee: Natasha Sant Anna Iwanicki
• Support Opportunities: Scholarships in Brazil - Doctorate