Prospective large-scale field study generates predictive model identifying major contributors to colony losses

Area of Science:

• Apiculture
• Entomology
• Veterinary Entomology

Background:

• Honey bee colonies in the USA have experienced high losses over the past decade.
• Numerous factors, including parasites, pathogens, environmental conditions, and management practices, contribute to these losses.

Purpose of the Study:

• To investigate the impact of bee pathogens, population dynamics, and overwintering conditions on colony losses.
• To develop a predictive model for colony losses by analyzing the interplay of various stressors.

Main Methods:

• A large-scale, controlled trial was conducted across three US locations.
• Hives were untreated with antibiotics or miticides and remained stationary to isolate variables.
• Data on bee pathogens (e.g., DWV, IAPV), Varroa destructor infestation levels, and environmental conditions were collected.

Main Results:

• A linear association was observed between virus load (DWV, IAPV) in Varroa mites and bees at high infestation levels (>3 mites per 100 bees).
• The study's predictive model indicated that Varroa destructor and bee viruses, primarily DWV, account for approximately 70% of colony losses.
• Colony loss appears to be triggered by a combination of stressors rather than a single factor.

Conclusions:

• Insufficient control of Varroa destructor, a vector for bee viruses, significantly increases the risk of colony loss.
• Integrated pest management strategies focusing on Varroa mite control are essential for honey bee health.
• The synergistic effect of multiple stressors highlights the complexity of honey bee colony decline.