Does Vairimorpha (Nosema) ceranae like it cold, or with Lotmaria passim?

Vairimorpha (Nosema) ceranae is a globally prevalent midgut parasite of adult honey bees (Apis mellifera L.) frequently thought to be thermotolerant and cold intolerant. The apparent lack of cold tolerance is enigmatic given that V. ceranae survives and proliferates in both temperate and warmer climates. Here we will discuss the results of a viability and infectivity experiment where we provide evidence for cold tolerance of V. ceranae spores in two substrates commonly associated with honey bee colonies. Potential novel routes of transmission for the parasite based on these results will also be discussed. We will also present data from our ongoing work regarding the effects of V. ceranae and the trypanosomatid hindgut parasite Lotmaria passim on honey bee survival. We have found that honey bees infected with only V. ceranae reached >50% mortality 8 days earlier than those infected with L. passim only, and 4 days earlier than those infected with both parasites in honey bee hoarding cages. We will also discuss an emerging pattern we have observed from several of our experiments at both the hoarding cage and colony level regarding parasite intensity in honey bees inoculated with one or both parasites.