Variation in physiological host range in three strains of two species of the entomopathogenic fungus Beauveria

Rohrlich C, Merle I, Mze Hassani I, Verger M, Zuin M, Besse S, Robène I., Nibouche S., Costet L. 2018. Variation in physiological host range in three strains of two species of the entomopathogenic fungus Beauveria. PLoS ONE 13(7): e0199199. https://doi.org/10.1371/journal.pone.0199199

Abstract

Knowledge of the host range of a biocontrol agent (BCA) is fundamental. Host range determines the BCA’s economic potential, as well as the possible risk for non-target organisms. Entomopathogenic fungal strains belonging to the genus Beauveria are widely used as BCA, but our knowledge of their physiological host range is only partial. The aim of this study was to improve our understanding of the physiological host range of three Beauveria strains belonging to two species, Bhoplocheli and Bbassiana. We performed laboratory mortality bioassays to assess their pathogenicity and virulence against nine insect pests, belonging to three orders: Lepidoptera, Coleoptera and Diptera. Mortality rate, mean survival time and mycosis rate were used to estimate virulence. Pathogenicity was assessed as the capacity to cause a disease and induce mortality. Virulence was assessed as the severity of the disease based on mortality rate, mean survival time and mycosis rate. The results of this study revealed significant differences in the physiological host range of the three Beauveria strains tested. The three strains were pathogenic to all Diptera and Lepidoptera species tested. In the case of the Coleoptera, only the Bhoplocheli strain was pathogenic to the white grub Hoplochelus marginalis and only the Bbassiana strains were pathogenic to Alphitobius diaperinus. The Bhoplocheli strain was less virulent on Lepidoptera and Diptera than the two Bbassiana strains. The latter both exhibited very similar virulence patterns. The fact that Bhoplocheli and Bbassiana strains have different host ranges means that they can be used as BCA to target different pests. Impacts on non-target insects across multiple orders cannot be ruled out in the absence of ecological host range studies.

Publiée : 12/07/2018

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