Varroa mites brood cell

Based on an article about Varroa mites by Tina Sebestyen, published in Bee Culture Magazine.

The varroa mites’ infiltration within the brood cells is systematic. These mites cunningly target the safety of the brood cells, exploiting it as a parasitic base. While the foundress mite draws vital nutrients, it’s also a vector, introducing viruses into the developing bees. This dual attack from a single entity within the protected confines of a brood cell is what makes the varroa mite such a formidable adversary. Understanding the varroa’s target, the bee’s fat body, will offer insight into the depth of this disruption.

The Bee’s Fat Body: More Than Just a Storage Unit

Indeed, a bee’s fat body is like the central command, orchestrating multiple essential roles:

  • Energy Reservoir: This isn’t just a battery pack; it fuels metabolism, regulates brood nest temperatures, and offers support during the bitter cold of winter.
  • Nutritional Storehouse: The fat body ensures larvae get vital nutrients, like the 24-methylene cholesterol. Without this nutritional pillar, larval development hits a roadblock.
  • Defensive Fortress: Bolstering immunity, the fat body is the bee’s internal shield against viruses and bacteria. And mites, our hidden foes, often bring these pathogens as uninvited guests.
  • Production Unit: Vital components like wax and oil, crucial for hive building and bee protection, originate here.

So, when varroa mites target this central command, they’re disrupting the very essence of bee functionality and colony health.

Integrated Pest Management Techniques: A Deeper Dive into Our Arsenal

Indeed, with the depth of the varroa challenge laid bare, it’s evident that countering them requires a strategic approach.

  1. Drone Brood Removal: Varroa mites have a strategic edge during spring, with a pronounced preference for drone brood due to the extended pupation time. This preference makes drone cells an attractive breeding ground. Our first line of defense? Removing the initial batch of drone brood in early spring. By doing so, a significant portion of the mite population is eradicated right at the start of their reproductive cycle.
  • Hive Placement for Climate Control: Location is everything. Positioning hives in full sunlight serves a dual purpose. The warmth not only hampers mite and small hive beetle reproduction, but it also forces our bees to work more rigorously to regulate internal temperatures. These temperature spikes, though well-tolerated by bees, can be detrimental to mites, reducing their reproductive success.
  • The Significance of Brood Breaks: Life outside brood cell cappings is perilous for varroa mites. Without the security of the capped cells, mites become vulnerable—more susceptible to damage, prone to falling off bees, and easy targets for us beekeepers. Implementing strategic brood breaks, where there’s no capped brood, disrupts their breeding cycle. Additionally, continuous brood cycles can tilt the reproductive balance in favor of the mites. Hence, timely brood breaks (for instance in summer) are crucial.
  • Harnessing Screened Bottom Boards: A little alteration can make a significant difference. While initially believed to reduce mite numbers due to the fall-off mechanism, it was discovered that removing the slider from a screened bottom board resulted in lower humidity within the hive. This environment, ironically, becomes conducive for mite reproduction. The optimal strategy? Employ a screened bottom with a greased slider. This ensures mites that fall cannot climb back while maintaining a humidity level unfavorable for mite breeding.
  • Revitalizing with Fresh Comb: Just as we humans thrive in a fresh environment, bees prefer newer combs. Interestingly, older brood combs are four times more susceptible to mite invasions. As these combs age, accumulated cocoons and feces reduce the distance from the cell rim to the comb surface. This alteration makes it easier for mites to detect larval bee pheromones signaling capping readiness. Additionally, a study has shown that pesticides accumulated in beeswax can transfer to larvae during the pupation phase, further endangering our bees and potentially leading to resistance developments to these molecules. Regular comb rotations not only keep this environment fresh and less inviting to mites but also help in minimizing the risks posed by accumulated toxins.

Incorporating these refined IPM techniques is only one facet of an effective strategy against varroa mites. It’s crucial to understand that these methods and varroa mite treatments are complementary. For a holistic, robust defense against these persistent pests, beekeepers need to wield both tools in tandem. Relying solely on one measure is akin to trying to build a hive with only half the necessary equipment. Our bees deserve a comprehensive strategy, and it’s up to us to ensure we’re equipped with a full toolbox to effectively target and manage the mite menace.