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Advisor(s)
Abstract(s)
Nosema ceranae and Nosema apis are pathogens of honey bees that cause nosemosis, a disease implicated in colony losses worldwide. They are obligate intracellular pathogens infecting the midgut epithelial cells of
adult honey bees. Although N. ceranae was originally a pathogen specific of Apis cerana, currently, it is found
in Apis mellifera throughout most of the world. Due to their confined environments, which limited pathogen
transmission and dissemination, islands are unique places for epidemiological studies. There are only a few
Varroa destructor-free and possibly even fewer N. ceranae-free honey bee sanctuaries in the world, with the
Azores being one. Even though with the exception of Santa Maria and Flores, nosemosis has been present in
the Azores since 2008, the causal species has yet to be identified. Hence, this study aimed to determine the
prevalence and infection levels of Nosema spp. in the Azorean honey bees. In 2014/2015, 474 colonies were
sampled on Faial, Flores, Pico, Graciosa, São Jorge, São Miguel, Santa Maria, and Terceira. Additionally, São
Jorge, Santa Maria, Faial, and Terceira were re-sampled in 2020 with a total of 91 colonies. DNA was
extracted, and the diagnosis and Nosema spp. loads were obtained by multiplex PCR and RT-qPCR. The
findings indicate that N. ceranae appears to be the dominant species in the Azores. N. apis was only detected
in 2014/2015 with a very low prevalence (5.1%). N. ceranae prevalence varied between 2.7%, on São Jorge,
and 50.7%, on Pico. In 2020, N. ceranae positive colonies increased significantly on Terceira (57.1%) and
São Jorge (50.0%). N. ceranae was not detected on Santa Maria in both periods. Average infection levels in
positive N. ceranae colonies were usually medium to high (>10-7 ng/μl), with São Jorge colonies displaying
the greatest infection intensity (>10-5 ng/ μl). This study highlights the Azores archipelago as a unique place
for beekeeping, with islands free of N. ceranae and V. destructor, which are two important stressors that afflict
honey bees in the world.
Description
Keywords
Nosema apis Nosema ceranae Apis mellifera Real-time qPCR Prevalence Infection levels
Citation
Lopes, Ana Rita; Segura, Sara K.; Martín-Hernández, Raquel; Henriques, Dora; Pinto, M. Alice (2022). Colonization patterns of Nosema ceranae in the Azores archipelago. In ICBEES-International Congress on Bee Sciences. Online