Reproduction of Varroa jacobsoni in cells of Apis mellifera containing one or more mother mites and the distribution of these cells
S J Martin
This study was carried out in Devon, UK, using Apis mellifera colonies that were naturally infested with Varroa jacobsoni. Study frames with uniform areas of similarly aged sealed brood were used in order to reduce the possibility of fluctuations in infestation rate occurring. Cells were examined at regular intervals and their contents (mother mites and offspring at different stages of development, alive or dead) were determined. A total of 908 worker cells containing 1334 mother mites and 2671 drone cells containing 3455 mother cells were found in the 3228 worker cells and 16252 drone cells examined. The number of cells containing different numbers of mother mites did not differ significantly from a random (Poisson) distribution, irrespective of brood type (drone or worker), at any constant infestation level. The maximum number of viable adult offspring (male and female) observed in a single drone or worker cell was 16 and eight respectively. The mean number of eggs laid per mite in both drone and worker cells showed a small but steady decline as the number of mites per cell increased. Mortality of the offspring in drone cells containing up to four mother mites remained steady for the first three offspring then increased as the number of offspring in the cell increased. There was little difference in the number of viable female offspring produced in cells containing one or two mites. Competition or effects between the mother mites were less important than between their offspring and competition at the feeding site may be the major factor in offspring mortality.