Years ago, I did some research into varroa mites for the Wannabees which is a group for young beekeepers in the Back Yard Beekeeper’s Association. In doing so I came across a statistic that mites can multiply 12 times in twelve weeks. So, if you start with 12 mites you would end up with 144 mites in twelve weeks, and that would be “gross”!
While at the University of Nebraska-Lincoln, Judy Wu-Smart published a paper on the Sublethal Effects of Pesticide Residues in Brood Comb on Worker Bees. The two points that caught my eye involved the combined effect of chemicals on the length of time on brood. One is where the egg take’s 4 days instead of 3 to become larva, which the bees seem to remove at about day 8. Thus, creating a spotty brood pattern. The other point involves the possibility of increasing the time of the capped pupa.
Varroa mites already have one reproductive daughter in worker brood, and rarely 2. Anything that adds time to the capped portion of the bee’s brood cycle will increase the chance of a second reproductive mite. I found this interesting and decided to try and figure out where this 12 times factor comes from.
Once I had a method, I could change the percentages to see what could happen. In the following tables I make some assumptions, so it reflects only the reproduction of the mites.
- Overwintered mites die after producing 100 viable young mites.
- Varroa mites that hatch are baby mites, (B) which move to the next reproductive phase and become young mites(Y) and lay eggs. They leave a cell and move to the next cell and become mom mites(M) And lay another round of eggs. Then the mom mites die after the second reproductive cycle and are removed from the equation.
- Mite rearing starts February 1stwith 100 fertile mites.
- Bees have no resistance to mites, nor any attempt to reduce mite load by bees or beekeeper are taken.
- Drone brood is not counted.
Table One shows simple 1 to1 reproduction. Mite goes into a cell lays eggs, and because of the length of the bee’s development time only one new reproductive mite is produced. In three months, starting February 1st and ending at May 1st the math shows an increase of 13 times. I used 100% as opposed to 90 something % which skewed the numbers high, but I believe the math is correct. For the beekeeper, the numbers show how fast the mite population can grow and get out of hand.
Table Two represents the possibility of 2 reproductive mites as offspring in one bee brood cycle, due to an increase of the capped segment of the bee brood cycle. I stopped the math on June first when numbers spiked to over 200,000 mites.
Table Three is mites reproducing at a rate of 120%, I added 20% for drone brood and the occasional times when mites do have two reproductive offspring mites in worker brood. I stopped the math September first when mite counts would jump to over 400,000.
Thoughts to Ponder
Can chemicals in the comb increase the length of time of the capped phase of the bee’s brood cycle, thus increasing the rate of mite reproduction?
Can chilling the brood by the use of a screen bottom board also increase the time of capped bee brood cycle?
Are bees kept in large hives and encouraged to raise massive colonies, a breading playground for mites? Brood equals mites!
Are beekeepers sabotaging their own and other beekeepers with modern beekeeping practices ?????
Mites table 1
February 1 February 15 March 1 March 15 April 1
Over wintered 100y 100y 200y 300y
Mites Die 0 100m 100m 200m
100b 100b 200b 300b 500b
April 15 May 1 May 15 June 1 June 15
500y 800y 1300y 2100y 3400y
300m 500m 800m 1300m 2100m
800b 1300b 2100b 3400b 5500b
July 1 July 15 August 1 August 15
5500y 8900y 14400y 23300y
3400m 5500m 8900m 14400m
8900b 14400b 23300b 37700b
September 1 September 15 October 1 October 15
37700y 61000y 98700y 159700y
23300m 37700m 61000m 98700m
61000b 98700b 159700b 258400b
KEY:
Baby Mites (b) Become Young Mites (y) Become Mom Mites (m)
These are the viable These are mites These are the
New mites that mated that go into a cell mites that laid eggs already
and emerge from cells to start reproducing and moved to a second cell
for another round of egg laying
Mites table 2
February 1 February 15 March 1 March 15 April 1
Over wintered 100y 200y 600y 1600y
Mites Die 0 100m 200m 600m
100b 200b 600b 1600b 4400b
April 15 May 1 May 15 June 1
4400y 12000y 32800y 89600y
1600m 4400m 12000m 32800m
12000b 32800b 89600b 244800b
Mites table 3
February 1 February 15 March 1 March 15 April 1
Over wintered 100y 120y 264y 460y
Mites Die 0 100m 120m 264m
100b 120b 264b 460b 879b
April 15 May 1 May 15 June 1 June 15
879y 1595y 2958y 5464y 10107y
460m 879m 1595m 2598m 5464m
1595b 2958b 5464b 10107b 18685b
July 1 July 15 August 1 August 15 September 1
18685y 34550y 63883y 118119y 218403y
10107m 18685m 34550m 63883m 118119m
34550b 63883b 118119b 218403b 403826b