Aphids are phloem-feeding insects that, like other plant parasites, deliver effectors inside their host to manipulate host responses. The Myzus persicae (green peach aphid) candidate effectors Mp10 and Mp42 were previously found to reduce aphid fecundity upon intracellular transient overexpression in Nicotiana benthamiana. We performed functional analyses of these proteins to investigate whether they activate defenses through similar activities. We employed a range of functional characterization experiments based on intracellular transient overexpression in N. benthamiana to determine the subcellular localization of Mp10 and Mp42 and investigate their role in activating plant defense signaling. Mp10 and Mp42 showed distinct subcellular localization in planta, suggesting that they target different host compartments. Also, Mp10 reduced the levels of Agrobacterium-mediated overexpression of proteins. This reduction was not due to an effect on Agrobacterium viability. Transient overexpression of Mp10 but not Mp42 activated jasmonic acid and salicylic acid signaling pathways and decreased susceptibility to the hemibiotrophic plant pathogen Phytophthora capsici. We found that two candidate effectors from the broad-host-range aphid M. persicae can trigger aphid defenses through different mechanisms. Importantly, we found that some (candidate) effectors such as Mp10 interfere with Agrobacterium-based overexpression assays, an important tool to study effector activity and function.

The pepper weevil, Anthonomus eugenii , is a major pest on Capsicum species. Apart from natural spread, there is a risk of spread via international pepper trade. In the Netherlands, a pepper weevil outbreak occurred in 2012 and affected six greenhouses producing different sweet pepper varieties. The following year, a pepper weevil outbreak occurred in Italy. To trace the origin of the Dutch outbreak and to establish if the Dutch and Italian outbreaks were linked, we determined the mitogenomes of A . eugenii specimens collected at outbreak locations, and compared these with specimens from the native area, and other areas where the pest was introduced either by natural dispersal or via trade. The circular 17,257 bp A . eugenii mitogenome comprises thirteen mitochondrial genes typically found in insect species. Intra-species variation of these mitochondrial genes revealed four main mitochondrial lineages encompassing 41 haplotypes. The highest diversity was observed for specimens from its presumed native area (i.e. Mexico). The Dutch outbreak specimens represented three highly similar haplotypes, suggesting a single introduction of the pest. The major Dutch haplotype was also found in two specimens from New Jersey. As the Netherlands does not have pepper trade with New Jersey, it is likely that the specimens sampled in New Jersey and those sampled in the Netherlands originate from a shared source that was not included in this study. In addition, our analysis shows that the Italian and Dutch outbreaks were not linked. The mitochondrial genome is a useful tool to trace outbreak populations and the methodology presented in this paper could prove valuable for other invasive pest species, such as the African fruit moth Thaumatotibia leucotreta and emerald ash borer Agrilus planipennis .

Plots infested with Synchytrium endobioticum, the causal agent of potato wart disease, are scheduled, resulting in prohibition of potato cultivation of and cultivation of plants for planting. On account of robust resting spores that are present in infested soils, plots remain scheduled for 20 years. After this period, plots are intensively sampled and the presence of resting spores in soil is determined by direct examination. However, this method is very time-consuming and labour-intensive.In this paper, validation data for the molecular detection of resting spores in soil and its use to screen soils before direct examination are reported. In addition to the samples in the validation study, over 670 routine diagnostic samples were analysed by direct examination and molecular tests in parallel. Using an improved methodology, increased sensitivity was obtained relative to results reported from an interlaboratory comparison study in 2018, namely 7 spores per sample instead of 500 spores per sample. Molecular screening of the soil samples and direct examination of those samples testing positive was estimated to reduce the total hands-on time by half when compared to direct examination of all samples. We recommend inclusion of molecular detection in the update of EPPO PM 3/59 (3) and PM 7/28(2), and suggest that when all subsamples of a plot are negative, no additional direct examination or bio-assays are needed for descheduling (i.e. for releasing previously infested plots from official control). Comparaison de tests PCR en temps réel pour la détection de spores dormantes de Synchytrium endobioticum dans le sol et leur application potentielle pour la déréglementation des parcelles précédemment infestésLes parcelles infestés par Synchytrium endobioticum, l'agent causal de la galle

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The Asian tiger mosquito Aedes albopictus is an undesirable invasive mosquito species that causes considerable nuisance through its biting behaviour, and has been proven to transmit more than 22 different viruses under laboratory conditions. Human-aided transportation, the capacity of winter diapause, and possibly global warming have contributed to the global invasion of Ae. albopictus. The species was found for the first time in the Netherlands in 2005, and since 2010 has been found introduced at many locations throughout the country. Elucidating the origin of these introduced mosquitoes could help the authorities on the planning and evaluation of the risk-based surveillance of Aedes invasive mosquitoes. This study aims to determine the genomic diversity of Ae. albopictus that is represented within and between collection sites with a database consisting of Ae. albopictus specimens from past introductions in the Netherlands, specimens from populations from other regions in the world, and data from specimens present in databases. In this study, complete mitochondrial genomes were sequenced, a recommended marker for phylogeography analysis of Ae. albopictus. Metadata is presented in a Nextstrain build containing 254 Ae. albopictus genomes up to October 2020. Overall, the phylogeny results of the Nextstrain build reveals a low mitogenomic diversity within Ae. albopictus. Genomic diversity of Ae. albopictus specimens found in the Netherlands fall within one main cluster which is hypothesised to represent the globally invasive strain of the species. Other organisations are stimulated to share data or materials for inclusion and improvement of the Nextstrain build, which can be accessed at https://nextstrain.nrcnvwa.nl/Aedes/20210728 .