So Ian is showing the work in progress hive model on Youtube now.
Find it here:- Hive model
We have seen in numerous presentations the population dynamics chart originally produced by Randy Oliver with respect to bee population growth and dynamics in a healthy bee colony. It was a bit inspiring, but, we wanted something that would allow us to modify the start conditions and see how different start conditions would change the dynamics.
Honeybee duties are based on the age of the bee, there is a pretty good description found on Wikipedia.
The way the calculations work is strait forward. The starting population is distributed by age based on the start condition. A package is an even spread of bees of all ages. A wintered unit starts out with all winter bees, and a nuc starts with a population of all house bees, along with the number of brood frames selected, with the brood spread evenly over all ages.
When the simulation runs, the date is advanced one day at a time, and all the bees / brood are aged by a day, then tally up how many in each age group to plot population of that group. During the process realistic restrictions are incorporated, ie the queen doesn’t lay more eggs than the current population can support for feeding and incubating brood.
Some assumptions are made during the simulation. It is assumed the bees will have all the necessary protein and carbohydrates available for feeding the brood, if not available naturally then they should be beekeeper provided. It is also assumed there is always enough comb available for eggs to be laid at the best rate the queen is capable of. During the buildup, it’s also assumed that a queen doesn’t go from 0 to thousands of eggs overnight, it takes time for the rate of eggs laid to ramp up. An arbitrary number was chosen, on any given day queen will be capable of at least a couple hundred eggs, and the rate of eggs being laid can increase by 25% day over day, so when the simulation first starts, there is a ramp on the rate of eggs going into cells.
Winter bees are a special case, and there is really no good numbers available in literature for modelling the winter honeybees. But we can make some intelligent guesses. Looking at the division of labour by age, bees are nursing brood from ages 3 thru 11 days for a total of 8 days. Larvae is open from day 3 thru 8 for a total of 6 days, so the ratio of nurse bees to open larvae is 4/3 in a hive with a steady state population at maximum potential. During the fall slowdown there is a period where the ratio of nurses to open larvae gets much larger, so we have a surplus of nurse bees that have the body fats of the freshly emerged bees, but are not expending them nursing new larvae. These are the bees we allocate to the ‘winter bees’ population. Conversly in the spring, when winter bees are pressed into nursing duty, that starts the aging clock for them to age out on the normal bee age cycle. During spring buildup, the way this is modelled, when there is a shortage of nurse bees for the open larvae, bees are taken from the winter bees category and placed into the nurse bee role at age of 4 day, and then allowed to age out in the normal progression.
Ofc, we all know, there is bee die-off thru the winter, not all of the winter bees survive thru till the spring. Again, to simulate this I have found no strong references in the literature for death rates, so we go back to our own experience and look at what we’ve seen in colonies in our back lot. My best guesstimate for that is, winter bees die off at approximately 10% per month.
On the ‘To-Do’ list. The next addition will be modelling growth of the drone population along with the worker bees. When that’s done, plan is to home in on the biology of varroa mites, and introduce a varroa mite population that runs in conjunction with the bee population model.