The effects of artificial diets containing free amino acids versus intact proteins on biomarkers of nutrition and deformed wing virus levels in the honey bee

Authors: TAPIA, JOSE' CARLOS - University Of Guadalajara; TAPIA,, JOSÉ MARÍA - University Of Guadalajara; Alburaki, Mohamed; CHAN, PHILENE - US Department Of Agriculture (USDA); SANCHEZ, ROGELIO - University Of Guadalajara; MACÍAS-MACÍAS, OCTAVIO - University Of Guadalajara; Corona, Miguel

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/28/2025
Publication Date: 4/2/2025
Citation: Tapia, J., Tapia,, J., Alburaki, M., Chan, P., Sanchez, R., Macías-Macías, O., Corona, M.V. 2025. The effects of artificial diets containing free amino acids versus intact proteins on biomarkers of nutrition and deformed wing virus levels in the honey bee. Insects. 49. Article e0436. https://doi.org/10.3390/insects16040375.
DOI: https://doi.org/10.3390/insects16040375

Interpretive Summary: Nutritional stress, particularly the lack of pollen, is a significant factor contributing to honey bee colony losses. These losses can be traced back to insufficient pollen availability and the presence of viral diseases. Pollen substitutes, which are artificial diets, may help reduce colony losses, especially in areas with limited floral resources. These artificial diets typically contain amino acids in two forms: intact proteins, where amino acids are linked, and free amino acids, where the amino acids remain separate. This study compares the effects of pollen substitutes made with intact proteins to those made of free amino acids on the nutrition and health of caged bees. To evaluate the impact of these diets, we measured the levels of two nutritional markers and the load of one important honey bee virus—the deformed wing virus (DWV)—which affects honey bee health. Our findings indicate that while both types of pollen substitutes increase the levels of nutritional markers, they also elevate the levels of this virus. These results suggest that feeding certain pollen substitutes may not benefit bee colonies. This study could have implications for beekeeping operations that rely on pollen substitutes.

Technical Abstract: Pollen is bees' primary source of proteins. Using pollen substitutes could reduce colony losses in areas with limited floral resources. In this study, we compared the effects of pollen substitutes made from intact proteins versus free amino acids on bee survival, as well as the levels of vitello-genin (vg), major royal jelly protein 1 (mrjp1), and deformed wing virus (DWV). Our study re-vealed no significant differences in vg mRNA levels between bee-fed intact protein and free amino acid diets. However, mrjp1 mRNA levels were higher in bee-fed free amino acid diets, suggesting that the availability of amino acids affects the expression of this nutritionally regulated gene differently. Thus, the combined expression of vg and mrjp1 could be used to assess the nutritional value of different pollen substitutes. Our results also indicate that bee-fed diets rich in free amino acids exhibited high levels of DWV and increased mortality during the first week, even though they showed high expression of genes related to good nutrition. In contrast, bees fed an intact protein diet showed the lowest DWV levels during the first two weeks, although viral infection increased afterward. These results suggest that ingested free amino acids are quickly absorbed in the intestine, transported in the hemolymph, and taken up by cells, where they can facilitate viral replication. On the other hand, ingested intact proteins may undergo slower digestion and gradual release of amino acids in the hemolymph, which may not trigger an overt DWV infection. Possible interactions among Varroa mites, DWV infection, and nutrition are also discussed.