D3322: Early investigations into the comparative role of hydrogen peroxide in social bees and links to nutritional stress

Infectious disease is a challenge for eusocial insects who live in large social groups, resulting in a plethora of defensive mechanisms. One example is the production of hydrogen peroxide (H₂O₂) within honey stores. H₂O₂ is synthesized by glucose oxidase (GOX), an enzyme excreted by the hypopharyngeal gland, and maintained within honey stores at varying concentrations as a proactive defense against microbial growth. Developing larvae are also fed honey containing H₂O₂, to which they exhibit a high level of tolerance. The GOX required for the oxidation of H₂O₂ is costly to produce, and the oxidative stress caused by H₂O₂ consumption is costly to tolerate. Despite the high cost of H₂O₂ production and tolerance, it is a constitutive part of the honeybee social immunity response though it remains little investigated and the extent of its application, as well as the factors impacting production, are currently unclear.

This poster presents the preliminary results of a three-fold study: 1) investigating the link between nutrition and social immunity by comparing H₂O₂ production in honeybee and bumblebee colonies supplemented with different sugar feeds during periods of low nectar flow; 2) developing our understanding of H₂O₂ as a group-level immune investment by treating infected honeybee and bumblebee larvae with H₂O₂ spiked feed; and 3) the ability of bumblebee food stores and their associated H₂O₂ concentrations to protect against potential small hive beetle (Aethina tumida) spillover from honeybee hosts to bumblebees.