7.3.5. Recommendations for providing proteins to caged adult workers in the laboratory
Under natural conditions, adult workers meet the majority of their protein needs by consuming bee bread within 10 days of emergence (Crailsheim et al., 1992). This protein is vital for proper gland and tissue development, such as the hypopharyngeal and wax glands, flight muscles, and fat bodies (Maurizio, 1959), and consuming it can extend worker longevity beyond that of individuals which only receive carbohydrates (Schmidt et al., 1987). Although caged workers can survive extended intervals on carbohydrates alone, providing proteins is recommended when newly emerged or intra-hive workers of an undefined age are caged (see sections 4.2 and 4.3.4 for instructions on how to collect newly emerged and intra-hive workers for laboratory experiments). Protein is not required when flying workers are collected and maintained in the laboratory because they are likely greater than 10 days old and have therefore met their protein consumption demands (Winston, 1987).
Currently we cannot recommend one specific source of protein to provide to caged workers due to lack of data. Multi-floral beebread and corbicular pollen as described previously (sections 18.104.22.168 and 22.214.171.124, respectively) is sufficient for providing proteins as long as it contains minimal pathogens or environmental contaminants. This can be accomplished by sterilising bee products (section 7.6) and collecting from multiple colonies located in non-intensive agricultural areas or from those certified as organic. These multiple colonies ensure that the same, florally diverse pollen is provided to all workers during an entire experiment. Section 4.1 discusses how to select appropriate colonies to collect workers from; similar insights can be used towards the collection of pollen. Alternatively, inexpensive and nutritious pollen substitutes (section 126.96.36.199) that are subject to rigid quality control are ubiquitously available, and may provide a more standardised, sterile protein source to caged workers. Future studies should explore their use, especially those that are fermented by micro-organisms like bee bread to aid their preservation (Ellis and Hayes, 2009).
When used, protein can be provided ad libitum using feeders as discussed previously (section 7.3.2), and replaced at least every three days (section 7.3.4). Quality of protein (e.g. nutrition, contamination) should always be considered (see section 7.6 for food sterilisation).