What can result from a Varroa mite infestation?

A Varroa mite infestation can lead to the presence of viruses in the colony, primarily because the mites are known vectors for several bee viruses. When Varroa mites feed on honey bees, they weaken the bees and introduce harmful viruses into the bee population, such as Deformed Wing Virus (DWV) and Acute Bee Paralysis Virus (ABPV). These viruses can cause significant harm to individual bees and the overall health of the colony, leading to increased mortality rates and decreased productivity.

The other options do not accurately represent the effects of a Varroa mite infestation. Strong brood development is generally hindered due to the stress and disease pressure caused by the mites. Similarly, an increase in worker bee size is not a likely outcome; in fact, the overall health and size of the workers may decline as the colony suffers from virus infections and weakened immune responses. Finally, higher tolerance to viruses is not a result of Varroa infestations; rather, infestations typically reduce a colony's ability to cope with viral threats.