Varroa Mite Life Cycle and Reproduction
Varroa reproduce in capped worker and drone brood cells. Mature female mites (called mother mites or foundresses) enter cells just prior to capping. The foundress starts feeding on the brood within six hours of the cell being sealed, and feeding occurs regularly thereafter. The site on the larvae where the foundress pierces the cuticle to feed becomes the feeding area for her offspring. The first egg laid by the foundress develops into a male. The second egg develops into a female mite that mates with the male. The foundress mite feeds on the developing larvae, and can transmit several different viruses in the process. In worker brood, foundress mites produce 1-2 mated daughter mites. In drone brood, which takes longer to mature, 2-3 mated daughters can be produced. When the bee is fully developed, and emerges from the capped cell, the foundress mite and her daughters emerge and attach to adult bees. Mites on adult bees are called ‘phoretic mites’. Most commonly, phoretic mites attach to young worker bees tending developing brood (i.e., nurse bees). Nurse bees are the target of phoretic mites because the bees remain in the brood area and can serve as a vehicle to transport mites to brood cells. Phoretic mites can feed on adult bees, but when a brood cell of suitable age is found, the mite will detach and enter the cell to reproduce. Mites will enter and reproduce in worker brood, but preferentially enter drone brood if it is available.
Adult female mite - Varroa destructor
Adult varroa on developing pupa. Photo credit: Dennis Anderson
Credit: Picture from Bayer @ researchbayer.com