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Honey bee diseases and colony losses in Portugal. Results from the last nationwide survey


In many countries, beekeepers are reporting abnormally high honey bee colony mortalities. Portugal is no exception in this matter. Despite the fact that beekeepers' reports on colony losses have recurrently been made, it seems that colony losses are occurring more frequently and to a larger extent nowadays.

Portugal has approximatelly 15.000 registered beekepers that keep ± 550.000 colonies in circa 33.000 apiaries.

The last nationwide survey on honey bee diseases was carried out in 2006, focusing on 359 apiaries owned by different beekeepers spread throughout the country. Capped worker brood and adult honey bee samples were collected. Beekeepers were also asked to fill in a questionaire covering a number of honey bee colony sanitary issues. All the samples were analysed by the Portuguese Laboratory for Veterinary Research (national reference lab for bee diseases), leading to the following results.

Varroa destructor was found in samples representing 27.0% of the studied apiaries; Senotaina tricuspis larvae were identified in 19.8% of the adult bee samples; Nosema apis was present in 18.8% of the adult bees samples; Ascosphaera apis infested mummies were found in 3.7% of the brood samples; Malpigamoeba mellificae was recognized in 2.3% of the adult bee samples and Paenibacillus larvae was detected in 2.3% of the brood samples. Acarapis woody was only observed in 0.3% of the adult bee samples. Honey bee viruses, malnutrition or poisoning, as well as management suitability in a context of climatic changes, were not assessed.

Concerning the magnitude of annual colony mortality, an average value of 30.3% was reported. When asked about the reasons for such colony losses, 78.0% of the enquired beekeepers were unable to associate it with any specific cause, 15.0% blamed it on Varroa and 4% on American fool brood. Regarding seasonal episodes of colony mortality, winter was clearly the most critical season (53.5% of the enquired beekeepers reported colony losses overwinter), followed by autumn (17.3%), summer (10.9%) and spring (7.9%).

Despite the fact that Varroa seems to keep playing a key role in colony mortality in Portugal, it does not appear to fully explain contemporary losses, therefore creating a need to better ascertain honey bee colony death origins in Portugal. It is anticipated that COLOSS will be instrumental in this respect, as well as in moving closer to a set of reliable mitigating measures to counteract this alarming situation.


Honey bees; Diseases; Colony collapse disorder; Portugal

Tipo de Apresentação
Comunicação oral
Tipo de Revisão
Âmbito Geográfico
Área de Trabalho

Murilhas, A (2009). Honey bee diseases and colony losses in Portugal. Results from the last nationwide survey. IV Prevention of Honey Bee Colony Losses Conference. Faculty of Agriculture University of Zagreb. COST Action FA0803. Zagreb (Croácia): 28-28