Bees Can Swim: How Honeybees Escape Water & Impact of Insecticides

When a bee finds itself unexpectedly in water, its chances of survival may be higher than previously thought. Novel research from Michigan State University confirms that honeybees aren’t simply at the mercy of the currents; they can actively swim to safety, and importantly, they demonstrate a clear preference for darker areas – likely representing the shoreline or vegetation – as they navigate their way out of trouble. This surprising ability, recently detailed in Communications Biology, challenges the conventional understanding of bees as creatures solely adapted for flight.

The study, led by associate professor Zachary Huang in the MSU Department of Entomology, reveals that bees propel themselves across the water’s surface using a fascinating hydrofoil effect. As their wings become saturated, they lose lift, but the continued firing of flight muscles generates waves that push them forward. MSU Today reports that this isn’t random flailing; bees actively orient themselves toward darker visual cues, a behavior known as skototaxis.

How Bees Navigate a Watery Escape

Researchers tested this directional preference by placing individual bees in shallow bowls of water with a dark section along the edge. The results were striking: most bees consistently swam toward the darker area, demonstrating a clear and purposeful response. This suggests that the ability to locate and move toward potential escape routes is an innate behavior, increasing their chances of reaching safety and drying their wings for flight. “We found that bees don’t just move randomly when they’re on water,” Huang explained in the MSU news release. “They actually orient toward darker areas, which probably represent land, vegetation or the edge of a pool.”

Interestingly, the research extended beyond honeybees to include mason bees, a solitary species. Both male and female mason bees exhibited an even stronger attraction to darker areas than their honeybee counterparts, with female mason bees demonstrating a particularly efficient escape strategy, reaching the edge faster and covering shorter distances. This finding suggests that the ability to navigate water surfaces and orient toward escape routes may have evolved before the development of complex social structures in bees.

Insecticides and Impaired Navigation

The study also investigated the impact of thiamethoxam, a commonly used insecticide, on bees’ aquatic navigation skills. The results raise concerns about the potential disruption of this crucial survival behavior. Bees exposed to thiamethoxam lost their preference for dark areas, instead moving randomly across the water’s surface and taking longer, less direct routes to the edge. Further analysis revealed that insecticide exposure led to increased turning and reduced motor control, suggesting that the insecticide interferes with the neurological processes necessary for coordinated swimming.

“These bees eventually reached the edge, but not toward the dark section and their movement was much less efficient,” Huang noted. “The results suggest insecticides may interfere with the motor coordination needed for this behavior.” This finding underscores the importance of considering the broader ecological impacts of pesticide use, extending beyond foraging and learning to include less-studied behaviors like aquatic escape.

Why This Matters: Encounters with Water are Common

While it might seem like an unusual scenario, bees encounter water more frequently than many realize. Some bees actively collect water to regulate hive temperature, while others may inadvertently land on water surfaces while foraging near lakes, ponds, or irrigation systems. The ability to effectively navigate and escape from water could therefore be a significant factor in their overall survival.

“Even though only a slight fraction of workers collect water, the ability to escape when they fall in could still benefit the colony,” Huang explained. This highlights the potential for even seemingly minor behavioral disruptions to have cascading effects on colony health and resilience.

Beyond the Surface: Implications for Bee Research

This research also points to a broader need to expand the scope of bee behavior studies. Traditionally, research has focused heavily on foraging and learning, but bees engage in a wide range of activities that are often overlooked. The ability to swim and navigate water is a prime example of a behavior that could be crucial for survival but has received limited attention until now.

“Most pesticide research focuses on foraging or learning,” Huang said. “But bees perform many behaviors in the real world that we don’t often measure. This study shows that even something unusual like swimming can be disrupted.”

Understanding the Hydrofoil Effect

The mechanism behind the bees’ aquatic propulsion is particularly intriguing. As noted in a related study highlighted by Caltech Magazine, the saturated wings create a hydrofoil effect, generating waves that propel the bee forward. What we have is similar to how a boat moves through water, but on a much smaller scale. Researchers at Caltech observed that the bees generate strong waves with a distinct interference pattern, further contributing to their forward motion.

What Comes Next: Expanding the Scope of Pesticide Impact Assessments

The findings from this study have important implications for how we assess the impact of pesticides on bee populations. Current risk assessments often focus on direct effects on foraging and learning, but this research demonstrates that pesticides can also disrupt less-obvious behaviors that are critical for survival. Future research should aim to incorporate a wider range of behavioral endpoints into pesticide risk assessments, including aquatic escape abilities and other potentially vulnerable behaviors. Further investigation into the specific neurological mechanisms affected by thiamethoxam and other insecticides is also warranted.