7.2.3. Measuring carbohydrate consumption by caged adult workers in the laboratory

Consumption by caged workers can be measured by determining the change in weight or volume of carbohydrate over a given period of time, although most experiments measure the former (Barker and Lehner, 1974). Regardless of method used, consumption should be adjusted for length of feeding period and number of caged individuals to calculate food consumed per honey bee per 24 hours. An easy approach is to simply record consumption every 24 hours, but when this is not possible, recording within 36 hours will suffice, depending upon the size of the feeder and number of caged workers.

To measure average daily carbohydrate consumption per worker for each cage when feeders are not checked every 24 hours:

  1. Fill feeder with food.
  2. Record mass of food-filled feeder (MASSINITIAL).
  3. Provide feeder to caged workers; record date and time (hours and minutes) of insertion (TIMEINITIAL) and number of living caged workers (WORKERSINITIAL).
  4. Remove feeder after given interval (see section 7.2.4 for frequency of feeder replenishment).
  5. Record date and time of removal (TIMEFINAL), and number of living caged workers (WORKERSFINAL).
  6. Record mass of feeder (MASSFINAL)
  7. Determine mass of food consumed (CONSUMED) by subtracting MASSFINAL from MASSINITIAL
  8. Calculate number of hours (HOURS) the feeder was provided to caged workers using TIMEINITIAL and TIMEFINAL.
  9. Calculate hourly cage consumption (CONSUMEDHOURLYCAGE) by dividing CONSUMED by HOURS.
  10. Calculate hourly worker consumption (CONSUMEDHOURLYWORKER) by dividing CONSUMEDHOURLYCAGE by WORKERSFINAL; note that consumption is measured for the final living workers, rather than the initial number of living workers or an average of the number of initial and final living workers.
  11. Calculate daily worker consumption (CONSUMEDDAILYWORKER) by multiplying CONSUMEDHOURLYWORKER by 24.

        Consult section 7.7 to correct for mass of food stuff lost through evaporation.