Interactions between prevalent pathogens of honeybees (Apis mellifera)

The aim of the BEEHEAL project was to determine the phenology and interactions of the microsporidia Nosema ceranae and 5 highly prevalent and pathogenic honeybee viruses (DWV, BQCV, ABPV, IAPV and CBPV) in four Mediterranean countries: France, Israel, Portugal and Spain. The prevalence and phenology of these pathogens was monitored in four continental apiaries (one in each country) and three insular apiaries located on Ouessant Island (France) and on São Miguel and Santa Maria Islands (Portugal). Colonies were sampled during a 2-year study period, and honeybees were collected and analysed once every two months. Microsporidia detection was performed by conventional triplexPCR whereas viral loads were determined by RT-qPCR of the positive samples. Israel had the highest percentage of honeybees infected by Ǥ ” , followed by Spain, continental Portugal, and Ouessant, whereas the levels were the lowest in France mainland and it was not detected on the Portuguese Islands. The countries with the higher prevalence of viruses were France and Israel whereas the apiaries in Portugal and Spain had a lower percentage of colonies and individual honeybees infected by viruses. Moreover, CBPV was not detected in the latter countries. The viral load of colonies and honeybees coinfected with twoor more viruseswas positively correlated. Data analysedfrom all apiariestogether showed a negative correlation between the percentage of infected N. ceranae honeybees and the viral load. However, there was no correlation at the apiary level between N. ceranae and the viral load when analysed separately. Cross-tabulations showed a correlation in coinfection between N. ceranae with any of the three viruses: BQCV, IAPV and CBPV. In fact, honeybees coinfected by the microsporidia and one of these viruses had a higher viral load than honeybees infected only with the virus. This study showed that pathogen interactions differs greatly among countries and serves as a starting point for the development of epidemiological studies to unravel pathogen coinfections.

Keywords

Viral load Microsporidia Coinfection

URI

http://hdl.handle.net/10198/34656

Citation

Jabal-Uriel, Clara; Bonjour-Dalmon, Anne; Chejanovsky, Nor; Higes, Mariano; Le Conte, Yves; Lopes, Ana; Pinto, Maria Alice; Reyes-Carreño, Maritza; Soroker, Victoria; Martín-Hernández, Raquel (2022). Interactions between prevalent pathogens of honeybees (Apis mellifera). In EURBEE 2022: 9th European Conference of Apidology. Belgrado