According to the publication ‘Diet effects on honeybee Immunocompetence’ by Alaux et al. (see http://126.96.36.199/content/6/4/562.full) polyfloral pollen results in improved immunity in bees. This is established through increased glucose oxidase activity and the increased level of hemocytes. Scientists seek the cause of increased immunity in bees and not in the microorganisms that are present in the bees. The assumption is that glucose oxidase is produced by bees. This is incorrect. Glucose-oxidase (an iron-containing enzyme) is generally created by fungi and bacteria.
Hemocytes (blood cells) can also play a role in immunity. These are found in the hemolymph. They produce antimicrobial proteins. They could therefore play a role in inhibiting the microorganisms that the Varroa mite carries. It is possible that these microbial proteins are broken down by the metalloproteases created by the bacteria carried by the mite. This establishes a causal relationship between certain minerals and the loss of immunocompetence.
Even though much is known about immunity and immune responses, the statement made by Alaux et al. does not provide substantiation. Immunocompetence (= resistance to disease) is a collective term covering all sorts of reactions that organisms have to keep pathogens out and combat infection. By considering immunocompetence as a single factor, the approach put forward by Alaux et al. remains rather superficial. By using polyfloral pollen it is not possible to ascertain which exactly which factor is responsible for the effects observed.
Incidentally, in the publication by Alaux et al. immunocompetence was not attributed to the proteins in the pollen. This could mean that extra protein nutrition does not have a role to play in keeping bees healthy. That is remarkable, because in almost all publications on bee nutrition scientists assume that it is the proteins themselves (present in pollen) which are the deciding favorable factor for the bees.
From large-scale studies conducted in the USA it transpires that feeding bees with soy proteins does not reduce bee decline and winter mortality. From the large quantities that are fed to bee colonies (approximately 500 gram per week per colony) we can deduce that in fact, this kind of product contains too much ballast, that is of no benefit to the bees at all. Incidentally, these protein cakes are mostly used to allow a bee colony to regain strength quickly. They are not specially developed or intended to improve the health of the bees.
Alaux et al. did not include the minerals in the analysis. Regarding the diet of the bees, Brodschneider also places the emphasis on the proteins (see http://www.apidologie.org/index.php?option=com_article&access=standard&Itemid=129&url=/articles/apido/full_html/2010/03/m09120/m09120.html). No consideration is given to the fact that minerals are bound to proteins, for example to the proteins in the fat body. These minerals become available when the fat body reserves are tapped. If a protein-rich feed is given, this implicitly includes minerals.