Varroa jacobsoni Oudemans tolerance in selected stocks of Apis mellifera L

The relative tolerance of four honey bee stocks to Varroa jacobsoni Oudemans was investigated in field conditions. Apis mellifera carnica from Yugoslavia (ARS-Y-C-1), A m carnica from Canada (Hastings), F-1 hybrids from ARS-Y-C-1 and Hastings crosses, and a commercial Louisiana stock of yellow honey bees were studied. All three Carniolan stocks exhibited greater tolerance to V jacobsoni than the Louisiana stock. The Carniolan stocks survived longer with higher levels of Varroa infestation on both worker pupae and adult honey bees. Louisiana stock was more susceptible to Varroa infestation. Colonies died earlier. But, unlike other stocks, the Louisiana stock had lower levels of infestation at death. Regardless of the stock, Varroa had similar reproductive success based on the number of mites per infested pupa (1-10 mites), the number of foundress Varroa per infested pupa (1-3 females), the number of progeny per female (0-5 progeny), the number of progeny per infested pupa (0-7 progeny), and the proportion of infested pupae containing infertile foundresses (0-47%).