Experimental evidence of harmful effects of Crithidia mellificae and Lotmaria passim on honey bees

• Published in: International journal for parasitology Vol. 50; no. 13; pp. 1117 - 1124
• Main Authors: Gómez-Moracho, Tamara, Buendía-Abad, María, Benito, María, García-Palencia, Pilar, Barrios, Laura, Bartolomé, Carolina, Maside, Xulio, Meana, Aránzazu, Jiménez-Antón, María Dolores, Olías-Molero, Ana Isabel, Alunda, José María, Martín-Hernández, Raquel, Higes, Mariano
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.11.2020
• Subjects: Crithidia mellificae; Culture media; Experimental infection; Honey bee survival; Lotmaria passim; Morphotypes; Culture media; Crithidia mellificae; Experimental infection; Lotmaria passim; Morphotypes; Honey bee survival
• ISSN: 0020-7519; 1879-0135
• DOI: 10.1016/j.ijpara.2020.06.009

[Display omitted] •In vitro cultures of Crithidia and Lotmaria are possible with faster adaptation and multiplication rates in BHI medium.•Crithidia and Lotmaria are pathogenic for honey bees and reduce their lifespan.•Flagellated morphotypes obtained from the early stationary phase of culture are more pathogenic.•Lotmaria passim is more infective to honey bees than C. mellificae.•Both species invade the lumen of the ileum but no epithelial cell alteration was observed. The trypanosomatids Crithidia mellificae and Lotmaria passim are very prevalent in honey bee colonies and potentially contribute to colony losses that currently represent a serious threat to honey bees. However, potential pathogenicity of these trypanosomatids remains unclear and since studies of infection are scarce, there is little information about the virulence of their different morphotypes. Hence, we first cultured C. mellificae and L. passim (ATCC reference strains) in six different culture media to analyse their growth rates and to obtain potentially infective morphotypes. Both C. mellificae and L. passim grew in five of the media tested, with the exception of M199. These trypanosomatids multiplied fastest in BHI medium, in which they reached a stationary phase after around 96 h of growth. Honey bees inoculated with either Crithidia or Lotmaria died faster than control bees and their mortality was highest when they were inoculated with 96 h cultured L. passim. Histological and Electron Microscopy analyses revealed flagellated morphotypes of Crithidia and Lotmaria in the lumen of the ileum, and adherent non-flagellated L. passim morphotypes covering the epithelium, although no lesions were evident. These data indicate that parasitic forms of these trypanosomatids obtained from the early stationary growth phase infect honey bees. Therefore, efficient infection can be achieved to study their intra-host development and to assess the potential pathogenicity of these trypanosomatids.