Infectivity and virulence of Nosema ceranae (Microsporidia) isolates obtained from various Apis mellifera morphotypes

PORRINI, LEONARDO P.; PORRINI, MARTÍN P.; GARRIDO, MELISA P.; MÜLLER, FERNANDO; ARRASCAETA, LUCIANA; FERNÁNDEZ IRIARTE, PEDRO J.; EGUARAS, MARTIN J.

ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA

WILEY-BLACKWELL PUBLISHING, INC

Año: 2020 vol. 168 p. 286 - 294

0013-8703

The infection of honey bees, Apis mellifera L. (Hymenoptera: Apidae), by themicrosporidian Nosemaceranae is one of the factors related to the increase in colony losses and the decrease in honey productionobserved in recent years. However, these effects seem to differ depending on the climate zone.The range and prevalence of N. ceranae have increased significantly in the last decades, with differentconsequences in northern and southern temperate areas. The existence of various isolates of N. ceranaefrom distant geographical areas, which probably exhibit different degrees of virulence, couldexplain the different responses of the bee to the infection. The aim of this work was to compare theeffects of two N. ceranae isolates from different host populations from Argentina on honey bee survivalat two ages post-eclosion. Using cage experiments, we compared the development of infectionof worker bees through the estimation of daily bee mortality and spore counts. Host subspecies identityanalysis showed a strong similarity with Apis mellifera scutellata morphotype for the northernregion, with a greater hybridization between subspecies with European origin toward the central andsouthern regions. Genetic characterization of isolates from the three regions indicated only the presenceof N. ceranae. Infected bees survived longer than control bees, and bees infected at 5 days had alower survival than those infected at 72 h with isolates from the three regions. These differences insurvival matched the development of the N. ceranae infection, with differences in spore loads forinfected bees at 5 days. Our studies showed that Nosema infection and survival varied among the differentages post emergence of workers, and both increased as the honey bee aged. These differences insusceptibility to infection could be related to the immune response of bees of different ages or tochanges in the composition and succession of the intestinalmicrobiota throughout its ontogeny.