What characteristic of Varroa mites makes them a significant threat to honey bee colonies?

Varroa mites pose a significant threat to honey bee colonies primarily due to their ability to feed on the fat bodies of bees. This feeding behavior is detrimental because the fat bodies are crucial for maintaining energy reserves in bees. When Varroa mites attach to a bee, they not only consume the bee’s bodily fluids but also weaken the host, impairing its overall health. This can lead to a decline in the bee's ability to perform essential roles within the colony, such as foraging, nursing, and hive maintenance.

Although the rapid reproduction of Varroa mites contributes to their spread within a colony, it is the feeding on the fat bodies that directly impacts bee health and colony viability. Attacking primarily the queen is not accurate, as Varroa mites affect worker bees and brood more commonly. Lastly, while Varroa mites can be seen with the naked eye, their visibility does not contribute to their threat level; it is their biological interaction with the bees that is most harmful. Understanding this characteristic helps beekeepers implement effective management practices to protect their hives from these pests.