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Sentinel plants, plants in exporting countries that are inspected at regular intervals for signs and symptoms of invertebrate pests and microbial pathogens, are a promising tool for detecting and identifying harmful organisms of woody plants prior to their introduction into importing countries. Monitoring of sentinel plants reveals crucial information for pest risk analyses and the development of mitigation measures. The establishment of sentinel plants requires the import and plantation of non-native plants, which may be affected by the laws, regulations and administrative procedures in the individual countries. To evaluate the feasibility of sentinel plants as a global approach, this study aimed to summarise regulations and administrative procedures that affect the establishment of sentinel plants using non-native plants in countries worldwide. Information about national regulations of import and planting of non-native plant species was collected through a questionnaire survey, conducted among national representatives to the International Plant Protection Convention. Over 40 countries responded. The results show that legislations and regulations should not be major obstacles for a global use of the sentinel plants approach. However, the few existing experiences show that it can be complicated in practice. Here we describe the current state of art of the procedures that should be adopted to establish sentinel plants and we propose a strategy to circumvent the shortcomings resulting from the lack of a specific regulation.

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Lupinus nootkatensis is an exotic plant species that has been used for large‐scale sowing all around Iceland for land reclamation of eroded surfaces protected from livestock grazing. Until the early 1990s, L. nootkatensis was free from any significant arthropod herbivory in Iceland, whereas, after 1991, many outbreaks of native insect species, primarily Ceramica pisi and Eupithecia satyrata, have been recorded. These outbreaks have caused repeated total defoliation of extensive areas of L. nootkatensis, although the effects on its development are mostly unknown. We studied the effect of: (i) reduced herbivory; (ii) increased herbivory; and (iii) simulated increased herbivory, compared with (iv) unmanipulated herbivory, on defoliation and seed production of L. nootkatensis in a 3‐year field study within two sites at contrasting ages and successional stages. The results obtained showed that: (i) seed production across all treatments was negatively related to defoliation; (ii) reduced herbivory had a positive effect on the number of flowering stems and seed yield; and (iii) these effects depended on age and/or the successional stage because they were only significant in the older L. nootkatensis site. These findings indicate that arthropod herbivory may affect the invasiveness of L. nootkatensis in Iceland by reducing the seed production and the spatial distribution rate of late successional lupin communities.

A survey was made of the occurrence of Frankia, infective on Alnus, in some 40 soils from the whole circumpolar area. Some of these soils were also tested for the occurrence of Rhizobium infective on Trifolium pratense. Infectivity tests were performed by growing test seedlings in soil or soil suspensions. Frankia was detected only in very few soils, in spite of extended experimental periods. When nodulation took place, nodulation was observed in few test plants. Several of nodulated test seedlings never turned green, suggesting that Frankia was ineffective in N 2 fixation. An exception was soil from a site in the Faeroe Islands where nodulated Alnus had been introduced. This soil showed high nodulation ability and N 2 fixation was likely. It is suggested that lack of infective Frankia in the circumpolar soils studied may be because Frankia had not been spread to these sites, but does not necessarily mean that soil conditions are negative for Frankia. Infective Rhizobium was rare in the soils studied. Lack of infective root nodule bacteria in potential sites for soil reclamation calls for the need to inoculate the plants and also provides the opportunity for introduction of selected bacterial strains without competition from an endogeneous soil microflora.