1 3 Curr Genet DOI 10.1007/s00294-015-0492-z RESEARCH ARTICLE Tolerance of entomopathogenic fungi to ultraviolet radiation: a review on screening of strains and their formulation Éverton K. K. Fernandes · Drauzio E. N. Rangel · Gilberto U. L. Braga · Donald W. Roberts Received: 16 January 2015 / Revised: 3 April 2015 / Accepted: 25 April 2015 © Springer-Verlag Berlin Heidelberg 2015 used to date must be analyzed carefully due to consider- able variations in the methods used to garner the data. The current review presents tables listing many studies in which different methods were applied to check natural and enhanced tolerance to UV stress of numerous entomopatho- genic fungi, including several well-known isolates of these fungi. The assessment of UV tolerance is usually conducted with conidia using dose-response methods, wherein the UV dose is calculated simply by multiplying the total irradi- ance by the period (time) of exposure. Although irradiation from lamps seldom presents an environmentally realistic spectral distribution, laboratory tests circumvent the uncon- trollable circumstances associated with field assays. Most attempts to increase field persistence of microbial agents have included formulating conidia with UV protectants; however, in many cases, field efficacy of formulated fungi is still not fully adequate for dependable pest control. Keywords Metarhizium · Beauveria · ultraviolet radiation · fungal tolerance · formulation Introduction Many natural abiotic factors are known to limit the ability of fungal agent to biologically control arthropod pests, but solar ultraviolet (UV) radiation (UV-A and UV-B) is prob- ably the most detrimental environmental factor affecting the viability of fungi applied for pest control (Ignoffo and Garcia 1992; Moore et al. 1993). Most UV-tolerant iso- lates probably can survive a few hours of direct exposure to solar UV radiation, but UV-susceptible isolates succumb. In addition, the exposure of fungi to UV-B (Fernandes et al. 2007; Fargues et al. 1996; Braga et al. 2001d; Nascimento et al. 2010) or UV-A (Fargues et al. 1997; Braga et al. Abstract Ultraviolet radiation from sunlight is probably the most detrimental environmental factor affecting the via- bility of entomopathogenic fungi applied to solar-exposed sites (e.g., leaves) for pest control. Most entomopathogenic fungi are sensitive to UV radiation, but there is great inter- and intraspecies variability in susceptibility to UV. This variability may reflect natural adaptations of isolates to their different environmental conditions. Selecting strains with outstanding natural tolerance to UV is considered as an important step to identify promising biological control agents. However, reports on tolerance among the isolates Communicated by D. E. N. Rangel. This article is part of the Special Issue “Fungal Stress Responses”. É. K. K. Fernandes (*) Instituto de Patologia Tropical e Saúde Pública, Universidade Federal de Goiás, Goiânia, GO 746050-50, Brazil e-mail: evertonkort@ufg.br; evertonkort@yahoo.com.br D. E. N. Rangel Instituto de Pesquisa e Desenvolvimento, Universidade do Vale do Paraíba, São José dos Campos, SP 12244-000, Brazil G. U. L. Braga Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Universidade de São Paulo, Ribeirão Preto, SP 14040-903, Brazil G. U. L. Braga Research Support Center in Natural and Synthetic Products, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP 14040-903, Brazil D. W. Roberts Department of Biology, Utah State University, Logan, UT 84322-5305, USA