Science - November 4, 2016

Bees on the prowl for cannabis

Roelof Kleis

Bees can be trained to track down cannabis plantations. This was shown by an experiment carried out by Wageningen bee researchers for the Taskforce Brabant-Zeeland.

The idea comes from Wageningen students who, during the Academic Consultancy Training (ACT), were given the assignment to come up with innovative projects to put a stick in the wheel of cannabis cultivation by using Wageningen knowledge. The assignment came from the Taskforce Brabant-Zeeland, within which the police, judiciary and tax authorities collaborate to fight organised crime in both southern provinces.


The students came up with the idea to deploy bees as bio-informers. More specifically for this case: to use bees to track down cannabis plantations. Using honey bees as bio-informers is not a new concept. Wageningen researchers have previously used bees to chart pollution. However, that case was mostly about the passive collection of substances foreign to nature that would stick to bees while foraging.

This new project is all about active detection and bees trained to smell cannabis plants, explains researcher Coby van Dooremalen. According to her, bees are highly suitable for this job. They have an outstanding sense of smell and can be trained well. To achieve this, the researchers use classical conditioning. ‘We train the bees using sugar water. You start by getting them used to eating sugar water off a cotton bud. The next step is to pair that with the smell of cannabis, and eventually they also react to just the smell.’

You can teach bees many different things. I started with the smell of a cleaning agent
Coby van Dooremalen, researcher Bees@WUR

The bees react to the cannabis smell by showing what is called the proboscis extension reflex, which means that they extend their tongue. A sensor detects this. Van Dooremalen used the Vasor 136, a prototype that looks like a dust buster. The inner part of this instruments has room for 36 trained bees that, each in their own little harness, are waiting to smell.

Van Dooremalen says that training a bee generally only takes about an hour. ‘You can teach bees many different things. I started with the smell of a cleaning agent. That was successful. Later, I was given small cannabis plants to practise with.’ It has since become clear that this method works. Further research is necessary to learn more about the sensitivity of the method. Van Dooremalen and her tiny detectives were on television yesterday evening; they appeared in the Dutch programme RTL Boulevard.

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  • Alain Fiering

    Prachtig misschien ooit ook wel opsporen van kanker met bijenheel bijzonder bijen niet alleen voor het bestuiven mar ook vorm de bestrijding van wiet plantages