Black queen cell virus and Nosema ceranae coinfection in Africanized honey bees from southern Brazil

Abstract

Bees are fundamental in several aspects, especially in relation to plant biodiversity and pollination. Recently, immense losses are being faced in the number of Brazilian colonies, mainly in southern states of the country, which has a strong beekeeping activity. There are indications that, among the reasons for the losses, pathogens that affect the health of bees may be involved. Among them, the microsporidium Nosema and the black queen cell virus (BQCV) stand out for their prevalence. In this study, 92 colonies of 17 apiaries from southern Brazil were evaluated for infection by Nosema ceranae, Nosema apis and BQCV. Nucleic acid extractions and cDNA synthesis were performed from adult bee samples, followed by Reverse Transcription Polymerase Chain Reaction (RT-PCR) and multiplex PCR. Eight BQCV positive samples were subjected to sequencing. The results showed that N. ceranae and BQCV are circulating in the Southern region of the country, which may be the reason for the loss of colonies. N. apis was not found. N. ceranae was found in 57.6% (53/92) of the colonies and BQCV in 32.6% (30/92). Co-infection was found in 25% (23/92) of the colonies studied, a factor that is suggested to be reducing the hosts’ longevity due to the synergistic action of the pathogens. The samples submitted to sequencing indicated similarity of 96.8 to 100% between them, in addition to strong similarity with sequences from Asia, United States, Germany and Peru. This study reports the circulation of N. ceranae and BQCV in apiaries in southern Brazil, in addition to being the first phylogenetic analysis of the Brazilian BQCV sequence.

The Fungus Nosema ceranae and a Sublethal Dose of the Neonicotinoid Insecticide Thiamethoxam Differentially Affected the Health and Immunity of Africanized Honey Bees

“…In both groups, the percentage of infected bees was below 50%. A similar percentage of infected bees (<60%) was also reported in workers of AHB colonies from Brazil [72]. However, other studies have reported infectivity rates of 100% in EHBs inoculated with similar or lower concentration of Nosema spores than the one used in this study [49,73].…”

Presence of Known and Emerging Honey Bee Pathogens in Apiaries of Veneto Region (Northeast of Italy) during Spring 2020 and 2021

“…The BQCV infection mainly affects queen larvae and pupae instead and has the highest incidence in spring and early summer; BQCV infected adult bees normally do not exhibit outward disease symptoms [78]. Moreover, several previous reports linked BQCV disease outbreaks with infection of N. apis [74,78,81] and N. ceranae [25,[82][83][84][85], suggesting that these pathogens can act synergistically. Even if many apiaries analysed in this study showed co-infections of BQCV with N. ceranae, no statistically significant association was found, since BQCV infection was always present in almost all the hives.…”