Two's a party, is three a crowd?: How honey bees respond to infection with Nosema ceranae and Lotmaria passim

Nosema ceranae and Lotmaria passim are two digestive tract parasites of the honey bee that have individually been associated with honey bee colony losses in Canada, the U.S., and Europe. Unfortunately, honey bee colonies are often co-infected with these parasites, and we have little information regarding how the two parasites interact to affect honey bee health. We have investigated the effect of both parasites (single and mixed infections) on honey bee survival, and proboscis extension response (P.E.R.). Results of the survival experiment indicate that N. ceranae alone is more virulent than L. passim alone or in combination.  Honey bees inoculated with N. ceranae only reached <50% survival 8 days earlier than those inoculated with L. passim alone, and 4 days earlier than those inoculated with both parasites.  Results of the P.E.R. experiment suggest that infection does affect honey bee responsiveness to sucrose, but responsiveness does not vary with infection type, which will be further discussed.