RESUMO
Begomoviruses can be found in association with alphasatellites, which are capable of autonomous replication but are dependent on the helper begomovirus for systemic infection, encapsidation and vector transmission. Previous studies suggest that the presence of NW alphasatellites (genus Clecrusatellite) is associated with more severe symptoms. To better understand this interaction, we investigated the effects of two alphasatellites on infectivity, symptom development, viral DNA accumulation and vector transmission of three begomoviruses in three hosts. In tomato and Nicotiana benthamiana, all combinations were infectious. In Leonurus sibiricus, only the ToYSV/ToYSA combination was infectious. The presence of EuYMA increased symptom severity of EuYMV and ToYSV in N. benthamiana, and the presence of ToYSA was associated with more severe symptoms of ToYSV in N. benthamiana and L. sibiricus. EuYMA increased the accumulation of ToYSV in N. benthamiana but reduced the accumulation of EuYMV in tomato and of ToSRV in N. benthamiana. The presence of ToYSA decreased the accumulation of ToYSV in N. benthamiana and L. sibiricus. ToYSA negatively affected transmission of ToSRV by Bemisia tabaci MEAM1. Together, our results indicate that NW alphasatellites can interact with different begomoviruses, increasing symptom severity and interfering in the transmission of the helper begomovirus. Understanding this interaction is important as it may affect the emergence of diseases caused by begomovirus-alphasatellite complexes in the field.
RESUMO
O ciclo biológico do Amblyomma dubitatum, que se alimentava experimentalmente em coelhos domésticos, foi avaliado em condições laboratoriais e comparado com dados recentemente obtidos de infestações experimentais em capivaras (Hydrochaeris hydrochaeris), hospedeiros naturais para essa espécie. Os coelhos foram considerados hospedeiros experimentais adequados para larvas e ninfas porque quatro dos cinco parâmetros avaliados (número de carrapatos que ingurgitaram, período de alimentação, percentagem de carrapatos que realizaram muda e período de pré-muda) foram semelhantes aos resultados obtidos com capivaras. As percentagens diárias de desprendimento e de muda das larvas e ninfas confirmam os coelhos como hospedeiros experimentais adequados para esses estágios de A. dubitatum. Os resultados do experimento indicam que os coelhos são hospedeiros inadequados para os adultos.(AU)