Pathogenicity bioassays of Ascosphaera apis strains from Spanish provinces in bee larvae from Northern Argentina

Abstract

Beekeeping is one of the main economic activities in several countries, and Argentina has become one of the most important exporters of honey and other products from hives. Ascosferosis, an emerging disease caused by the fungus Ascosphaera apis, affects bee larvae, causing mortality in the colonies. While many studies have focused on the infections of European Apis mellifera bees, we studied hybrid Apis mellifera scutellata bees from northern Argentina and fungal strains isolated from commercial pollen from Spanish provinces, to determine the susceptibility of local bees to the entomopathogenic A. apis. Different groups of larvae were administered sugar syrup suspensions with ascospores at different concentrations: a lower concentration of 5 × 10³ spores/mL was used to know the susceptibility of the larvae and a higher concentration of 5 × 10⁶ spores/mL was used to determine the pathogenicity, resulting in an average infection of 30% of the mummified larvae. Besides, an intermediate concentration of 5 × 10⁴ spores/mL was administered, which allowed us to identify the most pathogenic strain at this concentration. This work provides the first approximation to the pathogenic effect of Spanish fungal strains on larvae of bees from northern Argentina.

Keywords:

• entomopathogen
• hybrid Apis mellifera scutellata
• pathogenicity
• larvae

Disclosure statement

The authors declare no conflicts of interest.

Additional information

Funding

Part of the experimental work was funded by Secretaría de Ciencia y Tecnica de Estudios Regionales, Universidad Nacional de Jujuy (SeCTER-UNJu). Tejerina Marcos Raúl has a postdoctoral studies fellowship from Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET-Argentina).