Seasonal variations of viral load in Piedmontese apiaries managed with brood removal or chemical varroa control
| Autor: | Molinatto G., Canuto F., Bassi E., Tagliabue M., Kretzschmar A., Bosco D., Marzachì C., Porporato M., Manino A. |
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| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: | |
| Zdroj: | XXVI ITALIAN NATIONAL CONGRESS OF ENTOMOLOGY, Torino, 7-11/06/2021 info:cnr-pdr/source/autori:Molinatto G., Canuto F., Bassi E., Tagliabue M., Kretzschmar A., Bosco D., Marzachì C., Porporato M., Manino A./congresso_nome:XXVI ITALIAN NATIONAL CONGRESS OF ENTOMOLOGY/congresso_luogo:Torino/congresso_data:7-11%2F06%2F2021/anno:2021/pagina_da:/pagina_a:/intervallo_pagine |
| Popis: | Varroa destructor mite is regarded as a major parasite of Apis mellifera, as it is responsible for many colony losses both directly and indirectly, by virus transmission. The current control strategies are based on the use of synthetic acaricides, which can compromise the quality of the hive products due to the presence of chemical residues, and whose activity is limited by the selection of resistant strains over time. Through a collaboration with the INRAE-PACA researchers from Avignon and with the Italian and French national associations of beekeepers UNAAPI and ADA France (Interreg-Alcotra project "Innov'api"), we tested a sustainable control technique against varroa. To this aim the innovative technique of brood removal combined with oxalic acid treatment was compared to conventional control with a synthetic acaricide (amitraz). In Piedmont, more than 200 colonies from both migratory and stationary apiaries managed by local beekeepers were monitored: the project took into account several parameters, such as population of adult workers and brood amount, productivity and health status of the hives. The latter was described by the assessment of varroa infestation levels (obtained by counting the phoretic mites) and infection levels of five viruses (deformed wing virus, DWV; acute and chronic bee paralysis virus, ABPV and CBPV; black queen cell virus, BQCV; sacbrood virus, SBV). Quantification of the viral loads was carried out through Real-time qPCR analyses, after reverse transcription of the RNA extracted from two pools of 40 nurse bees per colony. The "Innov'api" experimental design, by including at least six sampling dates per year and having covered three beekeeping seasons (2017-2020), has allowed us to describe the seasonal trends of the main honey bee viruses in relation to the population dynamics of the parasitic mite and host colonies. In Piedmont, a high prevalence of DWV, BQCV and SBV was found, with virus-specific fluctuations, whereas ABPV and CBPV were detected sporadically. However, considering the viral loads of the infected samples, we highlighted positive correlations between ABPV and DWV, as well as between BQCV and SBV. Showing higher levels in spring and summer, BQCV and SBV shared similar dynamics to those of the hives and positively correlated with the number of adult bees and brood. By reaching maximum peaks in autumn, DWV followed the trend of varroa population. Moreover, DWV load was positively correlated with the infestation levels of the hives. The overall results show that the brood removal technique is as effective, and sometimes quicker, in lowering the varroa population, as well as the associated viral load, as the conventional technique. |
| Databáze: | OpenAIRE |
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