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

0013-8703

The infection of honeybees,Apis mellifera L.(Hymenoptera: Apidae),by the microsporidian Nosema ceranae is one of thefactors related to theincreaseincolony lossesandthedecreaseinhoney production observed in recent years. However, these effects seem to differ depending on the climate zone. The rangeand prevalence ofN. 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 ofworkerbees through theestimationofdailybee mortality and sporecounts. Host subspeciesidentity analysis showed a strong similarity with Apis mellifera scutellata morphotype for the northern region, with a greater hybridization between subspecies with European origin towardthe 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 infectedbeesat5 days. OurstudiesshowedthatNosemainfectionandsurvivalvariedamongthedifferentagespostemergenceofworkers,andbothincreasedasthehoneybeeaged.Thesedifferencesin susceptibility to infection could be related to the immune response of bees of different ages or to changes in thecompositionandsuccessionoftheintestinalmicrobiotathroughoutitsontogeny