Within the framework of "Zukunft Biene" a "bee health and exposure monitoring in cases with suspicion of poisoning" was carried out in the years 2014-2016. The project module deals with acute cases of suspected bee poisoning, in which the causes of colony losses and bee damage are clarified by residue investigations. In contrast to the research projects MELISSA 2009-2011 and the bee exposure monitoring 2012 and 2013, the proven exposure of bees to the active substances clothianidin, imidacloprid and thiamethoxam has largely ceased, which can be attributed to the partial ban on certain neonicotinoids.
Honey bees can come into contact with various chemical substances inside and outside the hive. These compounds may originate from the application of veterinary drugs (e.g. Varroa control agents), plant protection products or biocides, but may also originate from formerly used and approved applications whose traces are still detectable in the environment. Here, all thesesubstances are collectively named pesticides. Bees are exposed to these compounds directly hrough flight and foraging activity or indirectly through contact with collected materials (nectar, honey dew, pollen, water).
The purpose of this module was to investigate reported cases of bee damage and colony losses with suspected bee poisoning. In cases of winter and late summer/fall losses and in cases of intentional poisoning, additional health checks (Varroa, Nosema and American foulbrood) were carried out at AGES (Department of apiculture and bee protection). Affected beekeepers were able to report such cases to the AGES and have their samples examined without cost. The residue analyses were carried out at PTRL Europe GmbH (Germany). Altogether a total of ca. 300 analytes were included in residue analyses, among which were also metabolites of insicticides.
Material for examination (bees, bee bread, pollen pellets, combs and wax foundations) were sampled by beekeepers and also by employees of the abovementioned department of the AGES during visits of apiaries.
In the project period 2014-2016, suspicion of poisoning was reported from 145 apiaries, 6 of which were suspected of intentional poisoning (malicious damage to property). A total of 194 samples from 122 stands (apiaries) were examined for residues. For 23 apiaries, this was not possible because either no sample material was available or varroosis or American foulbrood, respectively, were found to be the cause of colony losses.
The majority of reports of suspected poisonings came from Upper or Lower Austria, Styria, Burgenland and Carinthia. From Tyrol, Vorarlberg and Vienna only occasional reports were sent, no report came from Salzburg. Most of the reports were made during spring to summer (87 beekeeping operations) followed by the overwintering period (37 apiaries), the period of late-summer to fall (15 apiaries) and the cases of suspicion of intentional poisoning (6 beekeeping operations).
In the reported cases with suspicion of poisoning during spring and fall, the damage symptoms consisted mostly of bee losses, which were limited temporally and quantitatively and led more to a reduction in honey yield and problems with the production of young colonies rather than to colony losses. The bee-hazardous active ingredients clothianidin, imidacloprid and fipronil, which are covered by the EU partial ban in various crops, were detected in a small number of samples. In these cases, it is almost certain that there is a close connection between the bee damage which has occurred and the detected exposure. Thiamethoxam was not detectable in any sample. Thus, in a multiannual comparison, the proportion of exposed apiaries for these active substances covered by the EU partial ban has been significantly reduced from 93% in 2009 (results of the "MELISSA" project) to values between 16% and 19%, which were found in the course of the "Future Bee" project for the years 2014-2016.
In addition to the above-mentioned substances, a small number of samples contained several other insecticides (e. g. lambda-cyhalothrin, chlorpyrifos-ethyl, cypermethrin, etc.) as well as fungicides, herbicides, some metabolites and varroazides in varying frequencies and concentrations.
The most frequently detected substances in the 194 samples (single or pooled samples) examined were in descending order: Thiacloprid (42 ×), tau-fluvalinate (29 ×), piperonylbutoxide (25 ×), tebuconazole (22 ×), azoxystrobin (18 ×), biphenyl (16 ×), cyprodinil (14 ×), myclobutanil (11 ×) and spiroxamine (10 ×). All other substances were detected in less than 10 samples. The range of active substances detected is an indication that they originate from different sources of exposure (currently or in previous years used veterinary drugs, plant protection products, biocides, or ubiquitously present pollutants).
In cases of suspected intentional bee poisoning, partially severe total losses of bee colonies were observed, some of which could be confirmed by residue analysis. The bee-hazardous substances detected in such cases (e. g. lambda-cyhalothrin, dichlorvos, chlorpyrifos-ethyl, cypermethrin, cyfluthrin) and the synergist piperonylbutoxide, found in some cases in high concentration, are or were components of plant protection products and pesticides (biocides). It is not known how the bee colonies have come into contact with it, or how they have been brought into contact with it.
During the hibernation period, the reported cases with suspected poisoning were usually reported to have suffered high colony losses. In most cases, the residue tests were negative and active substances dangerous to bees could only be detected in individual cases. The health examinations often revealed varroosis – in a few cases also American foulbrood – as a very probable cause for the dying of the colonies.
Viewed as a whole, the results of this module of the project clearly show that colony losses and bee damage occur at different times and can have different causes. In order to achieve an improvement of the situation for bees in the future and a reduction of colony and bee losses, different approaches to the solution of occurring problems are also necessary, depending on the determined cause and its weighting.