Valstybinių Miškų Urėdija

In 2020, ASF occurred in wild boars throughout Latvia and Lithuania, and more than 21,500 animals were hunted and tested for the presence of the virus genome and antibodies in the framework of routine disease surveillance. The aim of our study was to re-examine hunted wild boars that tested positive for the antibodies and negative for the virus genome in the blood (n = 244) and to see if the virus genome can still be found in the bone marrow, as an indicator of virus persistence in the animal. Via this approach, we intended to answer the question of whether seropositive animals play a role in the spread of the disease. In total, 2 seropositive animals out of 244 were found to be positive for the ASF virus genome in the bone marrow. The results indicate that seropositive animals, which theoretically could also be virus shedders, can hardly be found in the field and thus do not play an epidemiological role regarding virus perpetuation, at least not in the wild boar populations we studied.

Key messageVolume predictions of sample trees are basic inputs for essential National Forest Inventory (NFI) estimates. The predicted volumes are rarely comparable among European NFIs because of country-specific dbh-thresholds and differences regarding the inclusion of the tree parts stump, stem top, and branches. Twenty-one European NFIs implemented harmonisation measures to provide consistent stem volume predictions for comparable forest resource estimates.ContextThe harmonisation of forest information has become increasingly important. International programs and interest groups from the wood industry, energy, and environmental sectors require comparable information. European NFIs as primary source of forest information are well-placed to support policies and decision-making processes with harmonised estimates.AimsThe main objectives were to present the implementation of stem volume harmonisation by European NFIs, to obtain comparable growing stocks according to five reference definitions, and to compare the different results.MethodsThe applied harmonisation approach identifies the deviations between country-level and common reference definitions. The deviations are minimised through country-specific bridging functions. Growing stocks were calculated from the un-harmonised, and harmonised stem volume estimates and comparisons were made.ResultsThe country-level growing stock results differ from the Cost Action E43 reference definition between − 8 and + 32%. Stumps and stem tops together account for 4 to 13% of stem volume, and large branches constitute 3 to 21% of broadleaved growing stock. Up to 6% of stem volume is allocated below the dbh-threshold.ConclusionComparable volume figures are available for the first time on a large-scale in Europe. The results indicate the importance of harmonisation for international forest statistics. The presented work contributes to the NFI harmonisation process in Europe in several ways regarding comparable NFI reporting and scenario modelling.

SummaryTwo studies were undertaken in a young New Zealand Pinus radiata stand to find a biological control agent for armillaria root disease caused by Armillaria novae‐zelandiae. Fresh thinning stumps were inoculated with saprophytic basidiomycete species as wooden dowel cultures or as homogenized aqueous mycelial suspensions, while all stumps were also inoculated with dowel cultures of A. novae‐zelandiae. After a period of between one and two years, no differences were found among test fungi in the percentage of Armillaria species isolated from stumps. However, inoculation of Stereum sanguinolentum as homogenate, and of Phlebiopsis gigantea, Sistotrema brinkmannii, Hypholoma acutum and Rigidoporus concrescens as dowel cultures, significantly increased their isolation incidence in comparison with stumps not treated by these species. Phlebiopsis gigantea, Resinicium bicolor and R. concrescens were also isolated with greater frequency nearer to their dowel inoculation points. Results suggest that P. gigantea and S. sanguinolentum should be included in further testing. However, a future trial is likely to be more effective if evaluation is directed towards the portion of the stump below the soil surface, particularly the root system.

Potato mop‐top virus (PMTV; genus Pomovirus; family Virgaviridae) is transmitted by the soil‐borne Spongospora subterranea f.sp. subterranea, a protoctist that causes powdery scab on potato. PMTV is distributed widely in the potato growing areas in South and North America, Japan and northwestern Europe. This article reviews the current knowledge on detection, distribution and control of PMTV with focus on the Baltic Sea region. Since the 1980s, PMTV has caused great economic losses to potato production in the Nordic countries (Norway, Sweden, Denmark and Finland), but its occurrence in other countries of the Baltic Sea region remained unknown. To fill this knowledge gap, harmonised sampling and virus detection procedures including bioassays and serological and molecular methods were employed by 21 research institutions to detect PMTV in potato tubers and soil samples in 2005–2008. Potato growing areas were widely contaminated with PMTV in the Nordic countries. Only the main seed potato production area in northern Sweden and the High Grade seed potato production zone in Finland were negative for PMTV. Intensive and systematic surveys in Poland in 2004–2008 found no evidence of PMTV, except a single PMTV‐infected tuber detected in 2008. Surveys in the Baltic countries (Lithuania, Latvia and Estonia) and northwestern Russia (Leningrad province) were negative for PMTV, except infection of minitubers in a screenhouse in Latvia in 2005. Varying percentages of tubers expressing spraing symptoms in Sweden, Norway, Denmark and Poland were infected with Tobacco rattle virus, and bioassays indicated similar results for Russia. Incidence of symptomless infections with PMTV was high in tubers of many potato cultivars. Here, we discuss the contrasting patterns of distribution of PMTV in the Baltic Sea region, factors playing a role in dispersal and establishment of PMTV in new fields and means for controlling PMTV and its spread to new areas. We emphasise the use of the current virus‐specific methods for the detection of PMTV in symptomless potato tubers and the high risks of disseminating PMTV to new fields and areas in viruliferous resting spores of S. subterranea in the soil adhering to seed tubers. PMTV‐resistant potato cultivars will provide the only sustainable means for preventing yield losses in the infested fields and the prospects of resistance breeding are summarised.

Diet composition and food niches of two common and widespread in Lithuania owl species, Tawny Owl (Strix aluco) and Long-eared Owl (Asio otus), were analysed from irregularly collected pellets. S. aluco was characterised by a more diverse diet and a wider food niche: 14 small mammal (93.1% of the recovered items) and two amphibian (5.2%) species, a few passerine birds (1.1%) and representatives of three Coleoptera groups (0.6%) were recovered, whereas for A. otus – nine small mammal and two Carabidea species. By numbers, primary food resources of S. aluco were C. glareolus (31.4%), M. arvalis (27.9%) and A. flavicollis (14.3%), whereas of A. otus - M. arvalis (70.8%), all Microtus voles constituting 95.2%. Diet diversity of S. aluco was more than twofold higher (Shannon's H = 2.62 vs. 1.16). According to biomass, main foods consumed by S. aluco were C. glareolus, M. arvalis and A. flavicollis (27.6, 25.0 and 22.4%, respectively). For A. otus, Microtus voles represented 95.8% of biomass consumed (M. arvalis – 64.3%). Levins' measure of food niche breadth for S. aluco was B = 5.51 and for A. otus – B = 2.22. The average number of prey items per pellet was 2.84 ± 0.11 (max. 10) for S. aluco and 1.75 ± 0.03 (max. 7) for A. otus.

Heterodera betae Wouts et al. was detected in Marijampolė and Panevėžys districts. A total of 18,121 sample was collected from 183,893 ha during a country-wide investigation carried out in 2000–2001. In 100 cm3; of soil, 800–900 larvae and eggs were found. Such a quantity is small and can not cause any serious economical damage for agricultural plants.

The number of parasites in a host population is often dispersed unequally so that a few hosts harbor most of the parasites. Social factors may be involved. In this pilot study, droppings of 12 stags of a “white” red deer (Cervus elaphus) bachelor group with known social hierarchy were collected. The samples were investigated for the presence of the first stage larvae of Elaphos-trongylus cervi, Varestrongylus sagittatus, and Dictyocaulus viviparus. Only larvae of Elaphos-trongylus cervi were detected in significant numbers. No signs of Varestrongylus sagittatus infection were found. A low density of Dictyocaulus viviparus was found in only 5 samples of the 12; hence, this parasite was omitted from further analysis. The deer were divided into two groups according to rank position of a stag: “high ranking” (the first to the sixth position within the hierarchy) and “low ranking” (all others). High-ranking stags had lower mean densities of the Elaphostrongylus cervi larvae per sample than the low-ranking stags (the first quartile, median, the third quartile: high-ranking 0.00,0.50,23.00; low- ranking 14.00, 32.50, 54.00; U-test, U= 6.50, P = 0.03). The results suggest that a relationship between social status of a stag and infection with some parasites may exist. Whether it is the parasite that influences the rank position of a stag or vice versa remains to be answered.

Abstract Previous studies on a "white" red deer herd at Zehušice, Czechoslovakia showed that a stag's antler casting and cleaning dates were related to his rank in the dominance hierarchy. The relationship was less apparent with antler cleaning than with casting. It was suggested that this is a consequence of disintegration of the bachelor group during the period of antler growth. A group of 14 individually recognised stags in a 1.26 km2 enclosure were observed 77 times between March 15th and August 22nd 1983. The number of stag groups, the distribution of stags into groups and the number of solitary stags was recorded on each occasion. For each observation the "relative dominance index" (RDI, rank position within a group divided by the number of stags in the group) was calculated for each individual. Correlation coefficients between antler cleaning dates and summed RDI values were calculated. As in previous seasons, and in contrast to the period preceding antler casting, the bachelor group disintegrated during the velvet period. As antler cleaning approached the stags tended to disperse into more groups and separate from other deer. The stags associated with others of similar rank and age. There was a close association between summed RDI values for individual stags for the last two weeks of the velvet period and dates of antler cleaning. Among pairs of stags which were closest associates during this period, the higher ranking stag always cleaned earlier. It is concluded that the disintegration of the bachelor group in the period before antler cleaning may be the major factor which causes a less apparent relationship between rank and the date of antler cleaning than between rank and date of antler casting. It is suggested that these two points in the antler cycle are regulated by hormones modulated by agonistic behaviour related to rank.