Detection of Honeybee Viruses in Vespa orientalis

Abstract

The Oriental hornet (Vespa orientalis) is spreading across the Italian territory threatening the health and wellbeing of honeybees by feeding on adult individuals and larvae and by plundering hive resources. Considering the capacity of other hornets in harboring honeybee viruses, the aim of this study was to identify the possible role of the Oriental hornet as a vector for honeybee viruses. Adult hornets were subjected to macroscopical examination to identify the presence of lesions, and to biomolecular investigation to detect the presence of six honeybee viruses: Acute Bee Paralysis Virus (ABPV), Black Queen Cell Virus (BQCV), Chronic Bee Paralysis Virus (CBPV), Deformed Wing Virus (DWV), Kashmir Bee Virus (KBV), Sac Brood Virus (SBV). No macroscopical alterations were found while biomolecular results showed that DWV was the most detected virus (25/30), followed by ABPV (19/30), BQCV (13/30), KBV (1/30) and SBV (1/30). No sample was found positive for CBPV. In 20/30 samples several co-infections were identified. The most frequent (17/30) was the association between DWV and ABPV, often associated to BQCV (9/17). One sample (1/30) showed the presence of four different viruses namely DWV, ABPV, BQCV and KBV. The detected viruses are the most widespread in apiaries across the Italian territory suggesting the possible passage from honeybees to V. orientalis, by predation of infected adult honeybees and larvae, and cannibalization of their carcasses. However, to date, it is still not clear if these viruses are replicative but we can suggest a role as mechanical vector of V. orientalis in spreading these viruses.

Detection of honey bee viruses in larvae of Vespa orientalis

“…Previous studies have already detected the presence of various honey bee pathogens in the three species of Vespa spp. (Nowar, 2016;Forzan et al, 2017;Mazzei et al, 2018;Mazzei et al, 2019;Highfield et al, 2020;Gabııń-Garcııá et al, 2021), and we have recently shown that adult individuals of V. orientalis can harbor five of the most prevalent honey bee viruses (Power et al, 2022). The prevalence of viruses in V.orientalis detected in our previous study reflected the epidemiological status of honey bee viral infection in apiaries across the Italian territory (Porrini et al, 2016;Bellucci et al, 2019;Bordin et al, 2022;Cilia et al, 2022), therefore, we have hypothesized that viruses could have been acquired through ingestion of infected honey bees.…”

“…Homogenization was then performed with the mechanical homogenizer TissueLyser (Qiagen, Hilden, Germany). For both types of samples RNA was extracted and purified from genomic DNA using the RNeasy Plus Mini Kit (Qiagen, Hilden, Germany) and subjected to reverse transcription (RT) PCR as reported elsewhere (Power et al, 2022). A multiplex PCR thermal protocol was executed to screen for the presence of six relevant honeybee viruses (ABPV, BQCV, CBPV, DWV, KBV and SBV) according to the procedure validated by Cagirgan and Yazici (2020) and successfully employed for V. orientalis in our previous study (Power et al, 2022).…”

“…For both types of samples RNA was extracted and purified from genomic DNA using the RNeasy Plus Mini Kit (Qiagen, Hilden, Germany) and subjected to reverse transcription (RT) PCR as reported elsewhere (Power et al, 2022). A multiplex PCR thermal protocol was executed to screen for the presence of six relevant honeybee viruses (ABPV, BQCV, CBPV, DWV, KBV and SBV) according to the procedure validated by Cagirgan and Yazici (2020) and successfully employed for V. orientalis in our previous study (Power et al, 2022). Moreover, in each PCR reaction, one no template control (NTC) was included as negative control, while gBlocks Gene Fragments (Integrated DNA Technologies, Coralville, IA, USA) mimicking ABPV, BQCV, CBPV, DWV, KBV and SBV intended amplicons were employed as positive controls.…”

Emerging Risk of Cross-Species Transmission of Honey Bee Viruses in the Presence of Invasive Vespid Species

“…[ 60 ]. Power et al [ 63 ] have identified this virus in the recently introduced V. orientalis in Italy. The DWV has been demonstrated to be present in more than 64 species of insects, including all the species of the genera Vespula and Polistes (with the exception of P. humilis and P. rothneyi ) treated in this document [ 65 , 66 , 69 , 71 ].…”

“…Another virus that has been extensively and frequently studied in Vespids due to its high incidence in honey bees is the BQCV [ 19 , 45 , 60 , 63 , 64 , 65 , 71 ]. This virus was also found in all the genera ( Table 1 and Table 2 ).…”