Black queen cell virus (BQCV) is a disease of the queen bee pupae which is caused by a cripavirus. BQCV causes mortality in queen bee pupae. Infected larvae die after the queen cell has been capped; after which they turn pale yellow, then brown-black. The walls of the queen bee cell also darken into a brown-black color. The larvae are surrounded by a tough saclike skin, resembling sacbrood infection. BQCV most frequently occurs in the spring and early summer.
TransmissionIt is suspected that BQCV is transmitted by nurse worker bees when they feed the larvae infected brood food. Infection of the colony with Nosema apis is thought to be another cause of BQCV.