## 3 Technological Advancements in Bee-Based Biosensors/Biomonitors
### Electronic Hives, Bee Counters, Chemical Monitoring at the Hive
Our counters have a self-diagnostic program that allows the user to check whether all of the emitters and detectors are working and that none of the passageways are blocked by debris or bees. We developed data summary applications for Windows computers in 1995, later adding touch-sensitive tablets and cell phones (Figure 7). We learned that users should be cautious about using counters with only a few portals. A properly designed bee counter must have many ingress/egress tunnels or else there will be congestion at the hive entrance, slowing down or blocking bees. In the worst case, this can lead to colony heat prostration. Finally, we learned that the daily return rate for healthy colonies tends to be in the mid- to high 90%. When exposed to an acutely toxic incident, that number can drop to the low 80s or lower. Chronic losses tended to be characterized by a decrease of one to a few percent fewer bees returning each day. We also found that the variability in flight activity from hive to hive at a given location tended to increase with exposure to toxins, as some colonies were affected more than others [48, 85]. Recent developments show progress towards accurate and more affordable bee activity counters. A capacitance-based counter (CBC) for bumble bees was described by [PERSON] _et al._, and a patent on their capacitance-based counter was obtained [85]. This team and others soon added image-based counting  
Figure 7: Screen captures of bee foraging data from bi-directional bee counters, 1995. The scrollable table and chart show a single colony’s daily forager activity (bee egress in red, bee ingress out blue) over 24 h. The data table can be accessed by tapping the activity plot at any point. A toggle brings up daily summaries for each colony by week. systems, as well as automated systems for monitoring locomotor activity [85, 86, 87, 88, 89]. Video activity monitoring is now offered commercially as an option for electronic hives fitted with scales by Arnia Remote Hive Monitoring in Europe and HiveMind in New Zealand. We also have experimented with a capacitance-based counter for our SmartHives(r). Our preliminary data indicates that queens, drones, and workers all produce a different change in counter capacitance. As such, a CBC should be capable of discriminating movements of drones (males), workers (female), and queens. [PERSON] _et al._[85] reported similar findings for their Bumble Bee counter. We are currently testing our next generation of SmartHives(r) in commercial beekeeping operations in the US. These electronic hive systems start with a scale integrated into a wooden or plastic pallet holding four or six colonies of bees. This palletized form factor is commonly used by large-scale, migratory beekeepers in the US. They load, ship, and unload palletized hives on trucks for transport from coast to coast. These customizable pallet-based systems have a programmable electronic processor, can be powered by alternating current (AC), battery, or a small solar panel, and have options to plug in a wide variety of low voltage analog and digital sensors. The sensor options include but are not limited to: scales, temperature probes, microphones, infrared sensors, relative humidity probes, moisture and fire detectors, movement detectors, counters, and weather stations. These SmartHive(r) pallets include on-board data storage. Data retrieval can be via USB port, Bluetooth(r), or other wireless communication in the bee-yard. Cellular or satellite communications are used for long-distance communications; they deliver alarms and data to a beekeeper's desktop computer or cell phone. Until very recently, limitations in terms of expense, power requirements, processing power, and durability of the necessary electronic components restricted the use of electronic bee and hive monitoring sensors to basic and applied research applications. However, advances within the past five years in essential enabling technologies, such as inexpensive, credit-card-sized computer processors with low power draw, eliminated many hardware limitations.