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

Abstract

The infection of honey bees, Apis mellifera L. (Hymenoptera: Apidae), by the microsporidian Nosema ceranae is one of the factors related to the increase in colony losses and the decrease in honey production observed 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 different consequences in northern and southern temperate areas. The existence of various isolates of N. ceranae from distant geographical areas, which probably exhibit different degrees of virulence, could explain the different responses of the bee to the infection. The aim of this work was to compare the effects of two N. ceranae isolates from different host populations from Argentina on honey bee survival at two ages post‐eclosion. Using cage experiments, we compared the development of infection of worker bees through the estimation of daily bee mortality and spore counts. Host subspecies identity analysis showed a strong similarity with Apis mellifera scutellata morphotype for the northern region, with a greater hybridization between subspecies with European origin toward the central and southern regions. Genetic characterization of isolates from the three regions indicated only the presence of N. ceranae. Infected bees survived longer than control bees, and bees infected at 5 days had a lower survival than those infected at 72 h with isolates from the three regions. These differences in survival matched the development of the N. ceranae infection, with differences in spore loads for infected bees at 5 days. Our studies showed that Nosema infection and survival varied among the different ages post emergence of workers, and both increased as the honey bee aged. These differences in susceptibility to infection could be related to the immune response of bees of different ages or to changes in the composition and succession of the intestinal microbiota throughout its ontogeny.

Defensive Behavior and Morphometric Variation in Apis mellifera Colonies From Two Different Agro-Ecological Zones of North-Western Argentina

“…The analysis using the COI-COII mitochondrial region was consistent with recently published works (Agra et al, 2018;Calfee et al, 2020;Porrini et al, 2020) that described the presence of genetic variability and a preponderant presence of African lineages (A1 and A4) in feral honey bee colonies mainly established in the north of Argentina. However, a saturation of AHBs in the north of Argentina previously described by Sheppard et al (1991) was not observed in our study.…”

“…A positive relationship between geometric morphometry variables and apiary location could indicate the presence of an environmental effect, as well as other factors not directly assessed in this study (such as parental gene effects). In addition, we found that sensitivity decreases when analyzing morphometric differences between haplotypes, as non-significant differences were detected, in accordance with recent results by Porrini et al (2020). These results could be due to phenotypic similarity between A4 and A1 and the ongoing hybridization process present in the northern region of Argentina, and suggest that geometric morphometry would not be sufficiently sensitive as an indirect marker of mitochondrial haplotype for these populations, as proposed by Kandemir et al (2011) for other populations.…”

Immune and antioxidant gene expression stimulation of Apis mellifera (Hymenoptera: Apidae) larvae by Saccharomyces cerevisiae from the brewering industry

“…Larvae were sourced from an experimental apiary of Apis mellifera mellifera × Apis mellifera ligustica hybrids (Porrini et al., 2020), with sister queens placed at J.J. Nágera Coastal Station (38°10′60″ S; 57°38′10″ W), Universidad Nacional de Mar del Plata, Argentina. Larvae (L1) were randomly selected from combs belonging to three different colonies, following the method described by Crailsheim et al.…”

“…Larvae were sourced from an experimental apiary of Apis mellifera mellifera × Apis mellifera ligustica hybrids (Porrini et al, 2020), with sister queens placed at J.J. Nágera Coastal Station (38°10′60″ S; 57°38′10″ W), Universidad Nacional de Mar del Plata, Argentina.…”

Effects of dietary supplementation with abscisic acid on Apis mellifera colonies confined in overwintering nucleus: studies on the adult honey bee population, nosemosis, and expression of nutrition- and immune-related genes

“…However, N. ceranae infections have been reported to be more severe in honey bee colonies than N. apis infections (Higes et al, 2008). In Argentina, genetic studies reported that the cosmopolite microsporidia species is N. ceranae (Medici et al, 2012;Porrini et al, 2020). In addition, other studies have concluded that nosemosis can act synergistically with other risk factors (Steinhauer et al, 2018).…”