Parasitic mite syndrome

What is parasitic mite syndrome?

When varroa reaches high population levels in a colony the brood starts to show a range of disease symptoms known as parasitic mite syndrome (PMS). When the colony is near death most of the brood will exhibit these symptoms.

Where to look for symptoms

Symptoms are found in cells both before and after capping. The cell cappings can appear sunken, dark and perforated identical to prepupae with AFB. However, unlike AFB, only larvae and prepupae are affected. Prepupae are usually stretched out along the bottom wall of the cell (Fig. 52). Affected larvae and prepupae vary in colour between white and yellow.

52_Fig_PMS_affected_honeybee_prepua — Figure 52: PMS affected prepupa stretched out along the lower cell wall

53_Fig_A_PMS_larva_spiralling_up_the_wall_of_a_cell — Figure 53: A PMS larva spiralling up the wall of a cell

Larvae may spiral up the walls of the cell (Fig. 53) like larvae with European foulbrood or half-moon syndrome.

The larvae may also curl around the entrance of the cell (Fig. 54) and at time,s form a dry scale around the entrance of the cell (Fig. 55).

54_Fig_A_PMS_larva_curled_around_opening — Figure 54: A PMS larva curled around the opening of a cell

55_Dried_honeybee_larval_remains — Figure 55: Dried larval remains curling around the top of the cell

Unlike AFB, PMS larval remains can be completely removed with a match stick (Fig. 56) and will not rope out. When PMS symptoms appear the colony is close to death. However, if a varroa treatment is administered, the colony may survive and the PMS symptoms will disappear.