With illegal drug use and possession steadily on the rise, law enforcement officials are looking for more efficient and accurate ways of detecting the presence of narcotics. While sniffer dogs are indeed quite valuable as sensitive biological detectors, ever-changing drug laws have made the so-called drug “alert” less reliable. Furthermore, retraining these dogs to identify a different set of controlled substances is not only time-consuming and difficult, but is also believed to a costly affair. In a study, recently published in the journal PLoS ONE, scientists, from the Germany-based University of Giessen, have successfully managed to use insects for the purpose of drug sniffing.

Illicit drug use is a real, undeniable problem in most countries across the world. According to the paper, up to 5-percent of the adult population (approx. 230 million people) used some kind of controlled substances at least once in the year 2010. Of this, around 0.6-percent (as many as 27 million individuals) are considered to exhibit substance addiction. Today, drugs, such as heroin, cocaine and others, are believed to cause nearly 0.2 million deaths, every year. Additionally, drug abuse is one of the chief culprits behind mental health problems and various kinds of violent crimes. Although authorities have become much more stringent in curtailing drug trafficking, constantly-changing drug laws and regulations have managed to confuse even the most well-trained sniffer dogs. For instance, marijuana use has been recently legalized in a number of U.S. states, including Colorado, Washington and Alaska.

While detection dogs are extremely efficient biosensors, retraining them is time-consuming and expensive. Moreover, dogs often develop close social bonds with human; something that might just bias their reactions in response to certain positive or negative stimuli. Using insects as drug sniffers actually does away with most of these problems. Insects possess incredibly efficient biosensors; their antennae being the most sensitive nature organs ever used for the purpose of drug detection. They can be bred and reared at very low costs, and can also be conditioned swiftly to react to certain types of volatiles. The antennae contain a set of specialized sensory organs, called sensilla, which are in turn capable of recognizing particular odor molecules. The odor is then converted into an electrical signal that is later recorded and measured by means of electroantennography (EAG). The paper states:

The antennal response in the presence of diluted samples can be used to establish a dose—response relationship, which confirms that genuine reception events have occurred in the antenna. Once it is confirmed that an insect species is physiologically able to sense an odor, conditioning studies can be used to determine whether the species can link the novel odor with a reliable and machine-readable behavioral reaction.

For the research, conducted at the Police Laboratory of Criminal Technology in Germany, the scientists studied the drug-sniffing abilities of three different insect species, namely the European grapevine moth, the western honeybee and the Madagascar hissing cockroach. Of them, the honeybee was the most impressive. This is because the honeybee is capable of accurately discerning volatiles related to heroin and cocaine samples. With the help of a specially-designed electroantennographic device, the researchers were able to establish a positive correlation between the antennal reactions of honeybees and the concentration of drugs in the given samples. Furthermore, the bees can be trained to identify the presence of even highly-diluted forms of pure heroin. The scientists note:

Trained honeybees could therefore be used to complement or replace the role of sniffer dogs as part of an automated drug detection system. Insects are highly sensitive to volatile compounds and provide an untapped resource for the development of biosensors. Automated conditioning as presented in this study could be developed as a platform for the practical detection of illicit drugs using insect-based sensors.

The bees can be trained, to avoid certain types of odor stimuli, by the application of mild electric shocks to the insects when exposed to the specific scents. According to the scientists, real drug-detecting situations would involve the use of a specialized chamber, containing 40 conditioned honeybees. A sensor could then be used to record and measure the reactions of the insects in response to the ambient scents. The researchers said:

For example, a multi-chamber device containing honeybees and cockroaches could be used in airports to screen luggage for heroin, cocaine and amphetamines… Such a device could be used to support the activities of sniffer dogs by providing a more specific readout for particular classes of drugs.

Despite the study’s apparent breakthrough, one is indeed left to ponder the effects of such technology on the already-dwindling populations of bees.

Source: PLoS ONE