An automated system for tracking and identifying individual nectar foragers at multiple feeders

Abstract

Nectar-feeding animals have served as the subjects of many experimental studies and theoretical models of foraging. Their willingness to visit artificial feeders renders many species amenable to controlled experiments using mechanical "flowers" that replenish nectar automatically. However, the structural complexity of such feeders and the lack of a device for tracking the movements of multiple individuals have limited our ability to ask some specific questions related to natural foraging contexts, especially in competitive situations. To overcome such difficulties, we developed an experimental system for producing computer records of multiple foragers harvesting from simple artificial flowers with known rates of nectar secretion, using radio-frequency identification (RFID) tags to identify individual animals. By using infrared detectors (LEDs and phototransistors) to activate the RFID readers momentarily when needed, our system prevents the RFID chips from heating up and disturbing the foraging behavior of focal animals. To demonstrate these advantages, we performed a preliminary experiment with a captive colony of bumble bees, Bombus impatiens. In the experiment, two bees were tagged with RFID chips (2.5 x 2.5 mm, manufactured by Hitachi-Maxell, Ltd., Tokyo, Japan) and allowed to forage on 16 artificial flowers arranged in a big flight cage. Using the resulting data set, we present details of how the bees increased their travel speed between flowers, while decreasing the average nectar crop per flower, as they gained experience. Our system provides a powerful tool to track the movement patterns, reward history, and long-term foraging performance of individual foragers at large spatial scales.

The psychophysics of sugar concentration discrimination and contrast evaluation in bumblebees

“…Nectar rewards were delivered to a nectar bucket inside the feeder platform, a vertical hole with 5 mm diameter and 7 mm depth. The design of the nectar bucket was made after Ohashi et al (2010) and included a plastic baffle to prevent bumblebees from getting nectar directly from the incoming tube (Fig. 1a).…”

“…The bucket is filled through a horizontal hole connected via a thread-to-barb connector ( 3 ) to a nectar tube ( 4 ). Direct access to the nectar in the horizontal hole is prevented by a plastic baffle (not shown here, see Ohashi et al 2010 for details). The tube receives nectar from either one of the two pumping systems, the tubes of which merge with ( 4 ).…”

Electronic identification technology for agriculture, plant, and food. A review

“…RFID technology is increasingly being used to study the behavior of insects (Robinson et al 2009) and allows an accurate and automated way of monitoring their activity (Ohashi et al 2010). An interesting approach is the use of RFID-tagged insects to monitor the impact of agrochemicals (Porrini et al 2014;Feltham et al 2014).…”

Getting to the start line: how bumblebees and honeybees are visually guided towards their first floral contact

“…A metallic identification tag is glued to the thorax (see Fig. 2) and detected by a reader placed at strategic locations (Streit et al, 2003;Sumner et al, 2007;Ohashi et al, 2010;Stelzer and Chittka, 2010;Decourtye et al, 2011;Silcox et al, 2011;Nachev et al, 2012;Katzenberger et al, 2013). We have recently adapted the technology to detect flower-naïve bumblebees exploring unrewarding flowers (Orbán and Plowright, 2013).…”