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These are the materials of the workshop “Determining design prevalences” organised in the project “Assessing the confidence in pest freedom gained in the past pine wood nematode surveys”. The aim of the workshop was to prepare the team members for eliciting design prevalences from risk managers, so that after the workshop, the team members could meet the risk managers of their country, and guide them to decide the design prevalences to be used in the project. The aim of the project is to build capacity for assessing the probability of pest freedom gained in past pine wood nematode (Bursaphelenchus xylophilus) surveys. The project is a co-operation between the Finnish Food Authority, the Estonian Agriculture and Food Board, the Lithuanian State Plant Service under the Ministry of Agriculture, the Norwegian Scientific Committee for Food and Environment and the Swedish University of Agricultural Sciences. The project is co-funded by the European Food Safety Authority (EFSA) (GP/EFSA/ENCO/2020/03 - Partnering grants), but EFSA is not responsible for any use of the project outputs., FI; en; PDF; PPTX; salla.hannunen@foodauthority.fi

The Warren root collar weevil, Hylobius warreni Wood (Coleoptera: Curculionidae), is an endemic pest species of conifers, particularly lodgepole pine (Pinus contorta var. latifolia) (Pinaceae), in British Columbia. Larvae feed on the roots and root collars of young trees, resulting in girdling damage and mortality or growth reductions. Population sizes of adult H. warreni have historically been difficult to assess due to a lack of operational sampling methods or chemical attractants for the species. Therefore, most previous population estimates have relied on indirect or incomplete measures of damage by immature individuals. In this study, we tested the Björklund funnel trap to assess its efficacy as a method to estimate H. warreni populations. Funnel traps were placed on all 182 trees in half of a small (~1 ha) lodgepole pine stand over four days and remained in place for 13 days after the last traps were installed. Adult weevils were captured, marked, and released on the bole of the tree on which they had been caught. It is likely that most of the adult weevils in the plot, which was isolated from any nearby lodgepole pine stands, were caught at least once and many were caught multiple times. Population sizes were estimated using both the Schnabel method and the Schumacher and Eschmeyer method, resulting in population estimates of 1.83-2.19 weevils/tree and 731-875 weevils/ha. These measures are within the range of population sizes estimated by previous studies. The results suggest the Björklund funnel trap may be an effective operational tool for population monitoring for this species and may also be an effective tactic in population reduction strategies.

Hylobius warreni Wood (Coleoptera: Curculionidae) is a pest of conifers, especially lodgepole pine (Pinus contorta var. latifolia Douglas ex Loudon) (Pinales: Pinaceae) in the Interior of British Columbia. The larvae feed on the roots and root collars and cause girdling damage, resulting in mortality or growth reductions. Previous research has suggested the adult weevils locate potential host trees by using random movements and vision, but likely not chemosensory cues. The purpose of this study is to determine if adult H. warreni respond to particular tree characteristics versus encounter potential hosts at random. Study A was a capture–mark–recapture experiment where weevils were captured on mature pine trees, while Study B was a tracking experiment within a young pine plantation. Weevils showed a preference for larger trees, and for trees that were closer to the weevil’s last known location. In Study A, weevils also avoided climbing trees in poor health, while in Study B, the weevils’ preference for taller trees increased as their distance from the weevil increased, as well as when taller trees were closer to other trees. Movement rates were similar to those observed in previous studies, were positively correlated with the average spacing of trees, and declined with time after release. This confirms previous findings that H. warreni may locate host trees by both vision and random movements, and that their movements are determined primarily by the size and distribution of potential host trees within their habitat.

Summary This survey quantifies the amounts of different plants and plant products traded into Sweden which may serve as pathways of entry for potential plant pests. Furthermore, data on the economic value of plants and plant products are reported, both in terms of production values as well as the value of trade from Sweden. In total, the volume of traded plants and plant material into Sweden was on average slightly more than 12 million tons per year. Of this, by far the largest part was different types of wood products, 10 million tons, followed by fruit and other types of plant based food, 1.5 million tons. Propagation material for different production systems was in terms of weight a small proportion of the total volume of traded plant goods into Sweden, reaching only about 52 000 tons, it is however a rather large source of living plant material traded. For example, an annual average of 39 million seedlings of forest trees were traded to Sweden each year. The amount of plants and plant material traded from Sweden totaled more than 9 million tons, with an annual yearly value of approximately 30 billion SEK. Hence, the trade from the country was less than into the country. The trade, both into and from Sweden was dominated by wood products, with a yearly average of 10 and 7.5 million tons respectively. The total annual economic value of plants and plant products produced in Sweden was more than 50 billion SEK, which was 1.6 times the value of the trade of plants and plant products from Sweden. A great majority of the production value is associated with forest trees, 27 billion SEK, and arable plants, 20 billion SEK. The economic value of vegetables and ornamentals and other plants produced in horticulture was approximately 2 billion SEK each. The estimated annual value of park- and street trees in Swedish cities, based on the cost of replacing them after 80 years, was 1.3 billion SEK. Fruits and berries constitute a minor part of plants and plant products produced, 777 million SEK. In conclusion the amounts of trade as wells as the economic value of plants and plant products quantified in this survey provides valuable information for determining pest specific risks for introduction as well as the potential impact if a species becomes established. The compilation of data also provides support for identifying potential pathways for plant pests.