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Practical beekeeping – bee poisoning

Wolfgang Ritter, OIE Reference Laboratory at CVUA Freiburg, Am Moosweiher 2, D79108 Freiburg, Germany

What to do?

When crawling or dead bees are suddenly found at the apiary or when there are changes in the brood, poisoning may be the reason. Good Beekeeping Practice requires immediate action to preserve the evidence. Immediate action is the only chance to identify the reason and to reduce the damage. Possible reasons for intoxication could be:

• the application of pesticides in agriculture, horticulture and forestry

• the malicious, criminal poisoning of bees

• nectar absorption from certain forage plants.

Evaluation of indicators

There are various indicators of intoxication:

• increased numbers of dead bees

• disturbance and biting attacks at the hive entrance

• strong and sudden decrease of flight activity

• changes, damage or gaps in the brood pattern

• slow development of the colonies (this is mainly in cases of chronic intoxication).

The symptoms of poisoning cannot always be readily distinguished from symptoms of disease. Sometimes they are caused by the natural death of old bees. Moreover, symptoms of less common diseases can be confused with intoxication. Misinterpretation can happen when neighbouring apiaries have been poisoned and your own colonies consequently appear the same.

First legal opinion

In many states of Germany the veterinary authorities, represented by the official bee expert, are required to give the first legal opinion. In all cases it is necessary to call an independent witness, for example a member of your beekeeping association, but never a relative. If no independent person can be reached, the police should be involved. As soon as the suspicion of poisoning is confirmed, or intoxication cannot be excluded, the authority for plant protection or any other competent institution should be involved. Often their representatives are authorised to enter agricultural ground to take plant samples. These officials know the plant protection measures recommended by the district agricultural office.

The grass at the entrances of hives should be kept short, to make it easy to recognise serious death of bees

Beekeepers registered with the authorities are warned to protect their colonies before pesticide applications take place

Preserving evidence

In cases of poisoning relevant samples often have to be rejected by the institutions charged with the examination, either because of insufficient quantity of material, because the material has decayed already, or because animal and plant material were not separated properly – prohibiting the collection of evidence that is adequate to show to an insurance company or to be presented in court.

How to take samples and how to forward them correctly is described under How to do (overleaf). In Germany it is obligatory to observe these recommendations.

Action before the official result

You should decide whether to stay at the location with the remaining colonies, or to move them to another place, at least for some time. As soon as the means of evidence are preserved and the scope of damage is defined, you can start cleaning. It is preferable to burn dead bees and combs. But be careful with the remaining material: it may be used again only after poisoning has been definitely excluded. Until then, the best way is to decide – with the opinion of an expert – what might be contaminated.

Action after the official result

As soon as poisoning is officially confirmed, the contaminated material has to be destroyed. The hives may be concerned as well. Wood should be burnt. Other materials, for example plastic hives, have to be disposed of as hazardous waste without further risk for bees. If the responsible party is identified, you can take legal steps according to civil law and claim compensation. If you are insured against such damage, contact the insurance company which will eventually recover from the person(s) responsible.

If the bees in front of the hive are soaked by rain or dew or already decayed, it is recommended to take samples from the bottom of the hive

Avoiding intoxication

In some cases, you can protect bees against poisoning by avoiding particular crops. Registered beekeepers or those who inform the official bee expert about the actual location of their hives can be warned before a pesticide application takes place. It is also advantageous to contact the farmers directly. If at a certain place poisoning occurs repeatedly, and if the reason cannot be found, it is better not to use it anymore. Other beekeepers should be informed, to protect them from similar negative experiences.

How to do

Registration of damage

The bee expert in charge states the damage:

• Number of affected colonies.

• Estimated number of dead bees.

• Scope of damage to the individual colonies (remaining strength, overwintering capacity, foraging ability).

• Photographs of damage (very important!).

• Gathering information from neighbouring apiaries.

• Completed papers provided by the competent authority.

Taking samples

• At least 1,000 bees, that is 100 g (about 0.5 litre) are necessary for chemical analysis.

• If possible, only bees that have just died or starving bees should be gathered.

• Bees with pollen loads should be stored separately, because they can eventually give a hint of the crop they had visited.

• The plant protection official gathers plant material of at least 100 g from the area under suspicion.

• If several areas are concerned, plant samples have to be separated.

• Bee and plant samples must be always stored and packed separately, because only then can clear evidence be preserved.

• Always put on an unused pair of single-wear gloves when a new sample is taken, or thoroughly clean hands with soap to avoid the spread of substances from one sample to another.

A sample of bees boxed and ready for dispatch for analysis

Storage and packing

Many substances decompose quickly and therefore cannot be identified during examination:

• Samples should be taken immediately after the damage has occurred.

• Decayed material is mostly useless for testing.

• In case of delayed forwarding (non-work days) the samples must be stored in a fridge.

• If the samples will reach their destination within one day, plastic bags can be used.

• In case of longer transport time, the samples have to be packed in airtight packing material of paper or cardboard first and then in plastic bags.

• To maintain the cold temperature as long as possible, two thermal packs per package should be used.

Checklist for Good Beekeeping Practice 

Only fresh sample material is taken and as quickly as possible Yes/No

Samples are always kept cool Yes/No

Bee and plant samples are always stored and packed separately Yes/No

Dead bees and combs of dead colonies are always burnt Yes/No

In case of poisoning, contaminated materials are decontaminated or destroyed Yes/No

Critical plant crops are avoided, if possible Yes/No

The location of hives are known to the official bee expert and/or the authorities Yes/No

BfD acknowledges www.diebiene.de as the original source of this article.