Deformed wing virus (DWV), a ssRNA(+) virus belonging to the Picornaviridae family within Iflavirus genus is a honeybee’s pathogen distributed worldwide and it is transmitted mainly by the bite of the ectoparasitic mite Varroa destructor which is its main biological vector (1,2). Within a bee family/beehive, horizontal transmission between infected and non-infected bees could also occur. Recent studies have proven the presence of DWV on flower pollen, pollen load and in other bee products supporting additional horizontal transmission routes (3). The possibility of other transmission routes due to honeybee predatory insects such as those belonging to the Vespa genus should be considered. Among those, Vespa crabro (European hornet) which is widely distributed in Italy and in particular the alien Vespa velutina (Asian hornet), which has been introduced only recently (2014) can cause intense honeybees loss and concern among beekeepers. The aim of our investigation was to evaluate the presence of DWV in V. crabro and in V. velutina specimens collected in Italy during 2016 and 2017, to reveal a possible virus spill over from A. mellifera to the predatory hornets. Total RNA was extracted from specimens and the presence of DWV genome evaluated and quantified by real time RT-PCR. In addition, a strand specific RT-PCR was used to confirm the presence of replicative form of the genome. Sequence analysis performed on positive samples confirmed the RT-PCR results and indicated that the virus belongs to the worldwide diffused and less virulent genetic variant DWV type A. As V. crabro and V. velutina are neither pollinators nor susceptible to Varroa destructor we can exclude transmission by exposition to flower pollen and parasite bite. By finding the replicative form of DWV genome in newly emerged V. velutina samples we can assume that wasps could have been exposed to the virus by eating DWV infected honeybees during their imago larval state. These results indicate the establishment of a possible new ecological equilibrium between honeybee prey and alien V. velutina predator.

First detection of replicative DWV genome in V. crabro and V. velutina specimens

Mario Forzan
;
Maurizio Mazzei;Simona Sagona;Giovanni Cilia;Patrizia Bandecchi;Antonio Felicioli
Ultimo
2018

Abstract

Deformed wing virus (DWV), a ssRNA(+) virus belonging to the Picornaviridae family within Iflavirus genus is a honeybee’s pathogen distributed worldwide and it is transmitted mainly by the bite of the ectoparasitic mite Varroa destructor which is its main biological vector (1,2). Within a bee family/beehive, horizontal transmission between infected and non-infected bees could also occur. Recent studies have proven the presence of DWV on flower pollen, pollen load and in other bee products supporting additional horizontal transmission routes (3). The possibility of other transmission routes due to honeybee predatory insects such as those belonging to the Vespa genus should be considered. Among those, Vespa crabro (European hornet) which is widely distributed in Italy and in particular the alien Vespa velutina (Asian hornet), which has been introduced only recently (2014) can cause intense honeybees loss and concern among beekeepers. The aim of our investigation was to evaluate the presence of DWV in V. crabro and in V. velutina specimens collected in Italy during 2016 and 2017, to reveal a possible virus spill over from A. mellifera to the predatory hornets. Total RNA was extracted from specimens and the presence of DWV genome evaluated and quantified by real time RT-PCR. In addition, a strand specific RT-PCR was used to confirm the presence of replicative form of the genome. Sequence analysis performed on positive samples confirmed the RT-PCR results and indicated that the virus belongs to the worldwide diffused and less virulent genetic variant DWV type A. As V. crabro and V. velutina are neither pollinators nor susceptible to Varroa destructor we can exclude transmission by exposition to flower pollen and parasite bite. By finding the replicative form of DWV genome in newly emerged V. velutina samples we can assume that wasps could have been exposed to the virus by eating DWV infected honeybees during their imago larval state. These results indicate the establishment of a possible new ecological equilibrium between honeybee prey and alien V. velutina predator.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11568/932690
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