Phenology of the Microsporidia Nosema ceranae in four mediterranean countries

The presence and prevalence of the Microsporidia Nosema ceranae was assessed as part of the BEEHEAL project during a 2-year study period (2018-2019). Monitoring took place in six apiaries located in four Mediterranean continental apiaries: France, Israel, Portugal and Spain, and two insular apiaries located on Ouessant (France) and on São Miguel (Azores archipelago, Portugal). Besides honeybee sample collection every two months, parameters on colony strength, honey production, beekeeping management and climate were recorded. The pathogen was not detected on São Miguel Island during the study. Infection at the apiary level showed that most of the colonies were positive to N. ceranae except in mainland France, where the percentage of infected colonies was the lowest and it fluctuated, with an increase in August in both years. The percentage of infected honeybees per colony varied among apiaries, with Israel having the highest mean levels (32.39%). Colonies in Spain and Portugal showed a similar pattern with the highest levels of infection in April 2018. Ouessant Island had a high percentage of infected honeybees in 2018 and it decreased on 2019. Temperature was not correlated with N. ceranae infection, although high temperatures combined with high relative humidity were associated to high infection levels in Israel. Intra-colony percentage of infection was positively correlated with honeybee population when all apiaries were analysed together. Honey production was not related with N. ceranae infection. Regarding queen replacement, infection levels in spring 2019 in mainland Portugal and Spain decreased in those colonies that had replaced the queen the previous summer (August 2018). Colony mortality varied amo ng apiaries, with mainland France and Spain showing the highest colony losses (47.6% and 39.1%, respectively). However, this parameter was not correlated with the levels of infection. These results allowed to compare the N. ceranae phenology among different countries showing that the infection is dependent on many factors. This information could assist in the development of beekeeping management strategies.

Keywords

Intra-colony prevalence Climate and beekeeping management effect

URI

http://hdl.handle.net/10198/34665

Citation

Jabal-Uriel, Clara; Bonjour-Dalmon, Anne; Chejanovsky, Nor; Le Conte, Yves; Lopes, Ana; Pinto, Maria Alice; Reyes-Carreño, Maritza; Soroker, Victoria; Martín-Hernández, Raquel (2022). Phenology of the Microsporidia Nosema ceranae in four mediterranean countries. In EURBEE 2022: 9th European Conference of Apidology. Belgrado