Brian Fleischmann
Introduction
Swarm traps (bait hives) are a simple tool used to capture honey bee swarms. Swarming is a natural process that occurs when a colony of bees splits its population and leaves the colony in search of a new home. Swarm traps are useful for both recapturing swarms from the beekeeper’s apiary or collecting feral (wild) bees. Swarms typically occur from successfully overwintered colonies and are therefore desirable for beekeepers to collect. Traps are typically baited with a solution to mimic the Nasonov pheromone, or other scents to help attract scout bees [2]. In this study, I examine if color can also be an important attractant for swarm traps. Studies [3-8] have shown that honey bees show a strong attraction to ultraviolet blue. Honey bees have trichromatic vision with ultraviolet, blue, and green photoreceptors in their compound eyes. Here I examine the effectiveness of using swarm traps with UV-induced blue fluorescence entrances. To do this, I collected comparative data on both the number of bees visiting/scouting the swarm trap, and the success rates on capturing swarms for the test (UV-blue) and control (white) entrances.
Table 1. Types of data logged at each location over the two-year period. | |||||
---|---|---|---|---|---|
Scout Bee Activity Logged | Swarm Captures Logged | ||||
Year 1 – 2020 | |||||
Location 1 | X | X | |||
Location 2 | X | ||||
Location 3 | X | ||||
Year 2 – 2021 (traps swapped) | |||||
Location 1 | X | X | |||
Location 2 | X | ||||
Location 3 | X |
Methods and Materials
The study was conducted from May-August in 2020 and 2021 during typical swarming season in Western New York. The swarm traps were designed using data from research done by Tom Seeley [1]. Swarm traps measured 17” tall, 8.5” wide and 19” deep to give a cavity volume of 1.59 cubic ft.
The entrance hole was 1.25” (3.2 cm). The traps contained five plastic frames: four undrawn, and one partially drawn with comb. The traps were painted brown to mimic tree bark color. Traps were baited weekly with a commercial swarm lure attractant spray. The trap entrances were 3D printed in a UV-reactive blue (test) filament, and a standard (non-UV) white filament (control). The UV-reactive blue filament glows bright blue under UV-light. Swarm traps were hung eight to 10 feet high in a tree bordering a honey bee forage location such as an open field.
In year one (Table 1), three geographically distant locations were chosen for data collection. All locations were setup with two traps, one test and one control, approximately 200 feet apart. At location one, scout bee interest at each trap was logged by counting the number of bees active around the trap for a duration of one minute. This count was done almost daily, or as weather permitted. Time of recording was between 11:30am-4:00pm. Traps were also monitored for successful swarm capture. Locations two and three were only monitored weekly for swarm capture success.
In year two (Table 1), the same three locations were chosen for data collection. Locations were in an identical setup to year one; however, swarm trap entrances were swapped from their year one tree location. Traps were swapped in order to determine if tree location preference could be a determining factor in swarm interest/trap selection. Location one scout bee interest was again logged by counting the number of bees active around the traps for a one-minute duration and monitored for swarm capture success. Locations two and three were only monitored weekly for swarm capture success.
Table 2. Swarm activity at each location and swarm trap selected. | |||||
---|---|---|---|---|---|
Swarm Captured | Trap Selected | ||||
Year 1 – 2020 | |||||
Location 1 | Yes | Blue | |||
Location 2 | Yes | Blue | |||
Location 3 | Yes | Blue | |||
Year 2 – 2021 (traps swapped) | |||||
Location 1 | Yes | Blue | |||
Location 2 | No | – | |||
Location 3 | Yes | Blue |
Results
Over the course of the study, a total of 90 days of scout bee activity data were logged (Figure 2). In the event that a swarm was confirmed as captured, scout activity data was logged but not included in the calculation of the average number of scout bee activity, as activity was monitored at over 20 bees per minute. Out of the 90 days of logged activity, the blue entrance had more scout bees 55 times, or 61.1% (Figure 3). The white entrance had a higher number of bees 21 times, or 23.3% (Figure 3). In total, blue had the same or a higher number of scout bees 76.67% of the time data was logged (Figure 3). In year one the blue entrance averaged four scout bees per minute, while white averaged 0.96 bees (Figure 4). In year two the blue entrance averaged 3.94 bees per minute, while white averaged 2.6 (Figure 4). The two-year combined average was 3.97 bees for blue, and 2.11 for white (Figure 4). The blue entrance showed an 88.2% increase in overall average scout bee activity over the white control entrance.
Over the two-year period of the study, a total of five swarms were captured (Table 2). In year one, each of the three locations had a successful swarm capture (Table 2). Each of the three swarms were captured in the blue entrance, for a 100% blue success rate (Table 2). In year two, two of the three locations were successful in capturing swarms (Table 2). Each of the two swarms were also captured in the blue entrance, for a 100% blue success rate (Table 2). Overall, blue was the selected swarm trap five out of five (100%) times.
Discussion
Results from this study suggest that honey bees show an increased attraction to the UV-reactive blue entrance. This increased attraction was most predominately shown in the increased average number of bees observed, as well as the frequency in which more bees were observed at the blue entrance comparatively to the white control entrance. This reaction was not entirely surprising due to previous research showing honey bees preference for UV-blue color [3-8]. It is also interesting that this preference was learned to be innate, and not learned from any previous foraging experience [8]. This color preference was found to be true even when bees were taught to expect a low reward as compared to other colors with a high reward [8]. It is hypothesized that this color preference is somehow encoded into the brain of the honey bee [8]. This study suggests that this color preference is evident even in scouting behavior, when no immediate rewards are expected. As most research regarding honey bee’s preference for UV-blue is found in foraging selection, this preference for swarm scout bees is somewhat of a revelation.
Finally, it remains to be asked how this color preference results in increased swarm capture success. This study revealed that when swarms were captured, they chose the blue entrance 100% of the time. This preference persisted even in year two when blue and white swarm traps were swapped to determine potential location bias. Once the swarm trap was discovered by a scout bee, it is possible that the location was able to be more easily discovered by additional scout bees due to the fluorescent nature of the entrance. Given that both the blue (test) and control (white) traps were identical in all other features, this seems to be the best explanation for the increase in scout activity and swarm selection rate. Swarm decision-making is known to be a democratic process [9], so the increased number of scout bees able to quickly find and relay the message to the swarm about the potential site should increase the odds of the swarm selecting that site.
Conclusion
This study revealed that UV-reactive blue swarm trap entrances nearly doubled the number of scout bees observed over the control. In addition, swarms chose the UV-blue entrance traps over the control white trap 100% of the time. This study demonstrates that visual stimuli are an important consideration in swarm trap attraction and selection.
References
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