The influence of cell size in Varroa reproduction

A study made by Mia Davidsson in 1992 at the Swedish University of Agricultural Sciences as an examination paper.

Comb foundation

When the mite can only reproduce in sealed brood cells, there is a hyphotesis that we can reduce the number of mites with a shorter capping stage. When smaller bees, (Apis cerana and Apis mellifera capensis), are more resistant to the mite, this research aim to find out if it is possible to get shorter capping stage with smaller cells in European bee colonies.

Three different foundations were used, 640, 770, and 900 cells/ The foundations were introduced in three different colonies at the University, and the postcapping stage and the weight of the bees were compared.

At Gotland, the place in Sweden with most infested colonies, the foundations were introduced into five colonies using the trapping comb method. Then cells were opened and inspected for Varroa mites in each comb. The offspring of the mother mites were divided in different groups and compared between the different cell sizes.

Diagram The distribution between reproducing and non reproducing female Varroa mites in the different types of wax.

The distribution of different types of offspring.

Distrubution of offspring 640 cells/ 770 cells/ 900 cells/ Total
Both female and male 73 89 85 247
Only female 27 11 32 70
Only male 10 17 17 44
Only protonymph 22 23 8 53
No offspring 18 10 8 36
Total 150 150 150 450

No difference could be found in postcapping stages between the cell sizes. There was a tendency to smaller bees in smaller cells. Comparision of the reproduction of the mites in different cell sizes showed no significant differences if the material was divided into two groups, fertile and non fertile mother mites. There were significant diffrerences between cell sizes in offspring composition but the result do not indicate that the reproduction of mites was substantially influenced by cell size on worker bee brood.