Pollinator activity and flowering in agricultural weeds in Sweden.

The extent to which weeds in arable land are useful to pollinators depends in part on the temporal pattern of flowering and insect flight activity. We compiled citizen science data on 54 bees and hoverflies typical of agricultural areas in southern Sweden, as well as 24 flowering weed species classified as pollinator-friendly in the sense that they provide nectar and/or pollen to pollinators. The flight periods of the bees and hoverflies varied greatly, but there were also some consistent differences between the four groups studied. The first group to fly were the early flying solitary bees (7 species), followed by the social bees (18 species). In contrast, other solitary bees (11 species) and hoverflies (22 species) flew later in the summer. Solitary bees had the shortest flight periods, while social bees and hoverflies had longer flight periods. Flowering of weed species also varied greatly between species, with weeds classified as winter annuals (e.g., germinating in autumn) starting early together with germination generalists (species that can germinate in both autumn and spring). Summer annuals (spring germinators) and perennials started flowering about a month later. Germination generalists had a much longer flowering period than the others. Weekly pollinator records were in most cases significantly explained by weed records. Apart from early flying solitary bees, all models showed strong positive relationships. The overall best explanatory variable was the total number of weeds, with a weight assigned to each species based on its potential as a nectar/pollen source. This suggests that agricultural weeds in Sweden provide a continuous potential supply of nectar and pollen throughout the flight season of most pollinators.

Impact of Laparoscopic Gastrectomy on the Completion Rate of the Perioperative Chemotherapy Regimen in Gastric Cancer: A Swedish Nationwide Study.

BACKGROUND: Omission of prescheduled chemotherapy following surgery for gastric cancer is a frequent clinical problem. This study examined whether laparoscopic gastrectomy (LG) had a positive impact on compliance with adjuvant chemotherapy compared with open (OG). METHODS: Patients with cT2-4aN0-3M0 adenocarcinoma treated with gastrectomy and perioperative chemotherapy between 2015 and 2020 were identified in the Swedish national register. Additional information regarding chemotherapy was retrieved from medical records. Regression models were used to investigate the association between surgical approach and the following outcomes: initiation of adjuvant chemotherapy, modification, and time interval from surgery to start of treatment. RESULTS: A total of 247 patients were included (121 OG and 126 LG, conversion rate 11%), of which 71.3% had performance status ECOG 0 and 77.7% clinical stage II/III. In total, 86.2% of patients started adjuvant chemotherapy, with no significant difference between the groups (LG 88.1% vs OG 84.3%, p = 0.5). Reduction of chemotherapy occurred in 37.4% of patients and was similar between groups (LG 39.4% vs OG 35.1%, p = 0.6), as was the time interval from surgery. In multivariable analysis, LG was not associated with the probability of starting adjuvant chemotherapy (OR 1.36, p = 0.4) or the need for reduction (OR 1.29, p = 0.4). Conversely, major complications had a significant, negative impact on both outcomes. CONCLUSIONS: This nationwide study demonstrated a high rate of adjuvant chemotherapy initiation after curative intended surgery for gastric cancer. A beneficial effect of LG compared with OG on the completion rate was not evident.

Differences in phenology, daily timing of activity, and associations of temperature utilization with survival in three threatened butterflies.

We used observational data collected during a mark-recapture study that generated a total of 7503 captures of 6108 unique individuals representing three endangered butterfly species to quantify inter-and intraindividual variation in temperature utilization and examine how activity patterns vary according to season, time of day, and ambient temperature. The Marsh Fritillary, the Apollo, and the Large Blue differed in utilized temperatures and phenology. Their daily activity patterns responded differently to temperature, in part depending on whether they were active in the beginning, middle or end of the season, in part reflecting interindividual variation and intraindividual flexibility, and in part owing to differences in ecology, morphology, and colouration. Activity temperatures varied over the season, and the Apollo and the Large Blue were primarily active at the highest available ambient temperatures (on the warmest days and during the warmest part of the day). The Marsh Fritillary was active early in the season and decreased activity during the highest temperatures. The relationship between individual lifespan and the average temperature was qualitatively different in the three species pointing to species-specific selection. Lifespan increased with an increasing range of utilized temperatures in all species, possibly reflecting that intra-individual flexibility comes with a general survival benefit.

A hexasaccharide from capsular polysaccharide of carbapenem-resistant Klebsiella pneumoniae KN2 is a ligand of Toll-like receptor 4.

Klebsiella pneumoniae serotype KN2 is a carbapenem-resistant strain and leads to the health care-associated infections, such as bloodstream infections. Its capsular polysaccharide (CPS) was isolated and cleaved by a specific enzyme from a bacteriophage into a hexasaccharide-repeating unit. With GC-MS, NMR, and Mass analyses, the structure of KN2 CPS was determined to be {→3)-ß-D-Glcp-(1→3)-[α-D-GlcpA-(1→4)-ß-D-Glcp-(1→6)]-α-D-Galp-(1→6)-ß-D-Galp-(1→3)-ß-D-Galp-(1→}n. We demonstrated that 1 µg/mL CPS could stimulate J774A.1 murine macrophages to release tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in vitro. Also, we proved that KN2 CPS induced the immune response through Toll-like receptor 4 (TLR4) in the human embryonic kidney (HEK)-293 cells. Strikingly, the hexasaccharide alone shows the same immune response as the CPS, suggesting that the hexasaccharide can shape the adaptive immunity to be a potential vaccine adjuvant. The glucuronic acid (GlcA) on other polysaccharides can affect the immune response, but the GlcA-reduced KN2 CPS and hexasaccharide still maintain their immunomodulatory activities.

Disturbance interval modulates the starting point for vegetation succession.

Increased frequency and new types of disturbances caused by global change calls for deepened insights into possible alterations of successional pathways. Despite current interest in disturbance interactions there is a striking lack of studies focusing on the implication of decreasing times between disturbances. We surveyed forest-floor vegetation (vascular plants and bryophytes) in a Pinus sylvestris-dominated, even-aged production forest landscape, unique because of the presence of stands under a precisely dated disturbance interval gradient, ranging from 0 to 123 yr between clearcutting and a subsequent megafire. Despite a dominance of early-successional species in all burned stands 5 yr after fire, progression of succession was linked to time since the preceding clearcutting disturbance. This was most clearly seen in increased frequency with time since clearcutting of the dominant, late-successional dwarf shrub Vaccinium myrtillus, with surviving rhizomes as an important mechanism for postfire recovery. Our results demonstrate the role of legacy species as significant drivers of succession. We conclude that the starting point for succession is modulated by disturbance interval, so that shortened intervals risk reducing development towards late-successional stages. We suggest that a decrease in long successional sequences caused by more frequent disturbances may represent a general pattern, relevant also for other forest types and ecosystems.

Under which humidity conditions are moss spores released? A comparison between species with perfect and specialized peristomes.

Dispersal is a fundamental biological process that can be divided into three phases: release, transportation, and deposition. Determining the mechanisms of diaspore release is of prime importance to understand under which climatic conditions and at which frequency diaspores are released and transported. In mosses, wherein spore dispersal takes place through the hygroscopic movements of the peristome, the factors enhancing spore release has received little attention. Here, we determine the levels of relative humidity (RH) at which peristome movements are induced, contrasting the response of species with perfect (fully developed) and specialized (reduced) peristomes. All nine investigated species with perfect peristomes displayed a xerochastic behavior, initiating a closing movement from around 50%-65% RH upon increasing humidity and an opening movement from around 90% RH upon drying. Five of the seven species with specialized peristomes exhibited a hygrochastic behavior, initiating an opening movement under increasing RH (from about 80%) and a closing movement upon drying (from about 90%). These differences between species with hygrochastic and xerochastic peristomes suggest that spore dispersal does not randomly occur regardless of the prevailing climate conditions, which can impact their dispersal distances. In species with xerochastic peristomes, the release of spores under decreasing RH can be interpreted as an adaptive mechanism to disperse spores under optimal conditions for long-distance wind dispersal. In species with hygrochastic peristomes, conversely, the release of spores under wet conditions, which decreases their wind long-distance dispersal capacities, might be seen as a safe-site strategy, forcing spores to land in appropriate (micro-) habitats where their survival is favored. Significant variations were observed in the RH thresholds triggering peristome movements among species, especially in those with hygrochastic peristomes, raising the question of what mechanisms are responsible for such differences.

Consequences of bioenergy wood extraction for landscape-level availability of habitat for dead wood-dependent organisms.

Stumps and slash resulting from forest clearcutting is used as a source of low-net-carbon energy, but there are concerns about the consequences of biofuel extraction on biodiversity. Logging residues constitute potentially important habitats, since a large part of forest biodiversity is dependent on dead wood. Here we used snapshot field data from a managed forest landscape (25 000 ha) to predict landscape scale population changes of dead wood dependent organisms after extraction of stumps and slash after clearcutting. We did this by estimating habitat availability for all observed dead wood-dependent beetles, macrofungi, and lichens (380 species) in the whole landscape. We found that 53% of species occurred in slash or stumps. For most species, population declines after moderate extraction (≤30%) were small (<10% decline) because they mainly occur on other dead wood types. However, some species were only recorded in slash and stumps. Red listed species were affected by slash and stump extraction (12 species), but less often than other species. Beetles and fungi were more affected by stump extraction, while lichens were more affected by slash extraction. For beetles and lichens, extraction of a combination of spruce, pine and birch resulted in larger negative effects than if only extracting spruce, while for fungi tree species had little effect. We conclude that extensive extraction decreases the amount of habitat to such extent that it may have negative consequences on species persistence at the landscape level. The negative consequences can be limited by extracting only slash, or only logging residues from spruce stands.

Population fluctuations and synchrony of grassland butterflies in relation to species traits.

Population fluctuations and synchrony influence population persistence; species with larger fluctuations and more synchronised population fluctuations face higher extinction risks. Here, we analyse the effect of diet specialisation, mobility, length of the flight period, and distance to the northern edge of the species' distribution in relation to between-year population fluctuations and synchrony of butterfly species. All butterfly species associated with grasslands were surveyed over five successive years at 19 grassland sites in a forest-dominated landscape (50 km(2)) in southern Sweden. At both the local and regional level, we found larger population fluctuations in species with longer flight periods. Population fluctuations were more synchronous among localities in diet specialists. Species with a long flight period might move more to track nectar resources compared to species with shorter flight period, and if nectar sources vary widely between years and localities it may explain that population fluctuations increase with increasing flight length. Diet generalists can use different resources (in this case host plants) at different localities and this can explain the lower synchrony in population fluctuations among generalist species. Higher degree of synchrony is one possible explanation for the higher extinction risks that have been observed for more specialised species. Therefore, diet specialists are more often threatened and require more conservation efforts than generalists.

Estimates of connectivity reveal non-equilibrium epiphyte occurrence patterns almost 180 years after habitat decline.

Habitat loss is a major cause of species decline and extinction. Immediately after habitat loss, species occurrences are not in equilibrium with the new landscape and more closely reflect the previous landscape structure. Species with slow colonisation-extinction dynamics may display long time-lags before reaching a new equilibrium. We investigated the importance of connectivity to current and historical dispersal sources with the aim of explaining the occurrence pattern of epiphytic lichens with different traits among 104 old oaks. We used oak survey data collected from 1830 and 2009 for a Swedish landscape where oak densities declined drastically shortly after 1830. We fitted a commonly used connectivity measure and estimated the confidence interval for the spatial scale parameter. Small differences in the spatial scale parameter resulted in large differences in model fit. Connectivity to trees in 1830 better explained the occurrence of three of the four species compared to the connectivity in 2009. The explanatory power of the historical landscape structure was highest for the species with traits that may result in a low colonisation rate--both a narrow niche (here few suitable trees) and large dispersal propagules. The results suggest that oak-dependent epiphytic lichens have not reached equilibrium with the spatial landscape structure 180 years after the drastic decline in habitat. For the long-term persistence of epiphytes associated with old trees, conservation efforts should focus on (1) protecting and restoring stands where specialised species with large dispersal propagules (i.e. with low colonisation rates) occur today and (2) promoting tree regeneration in their near vicinity.

Epiphyte metapopulation dynamics are explained by species traits, connectivity, and patch dynamics.

The colonization-extinction dynamics of many species are affected by the dynamics of their patches. For increasing our understanding of the metapopulation dynamics of sessile species confined to dynamic patches, we fitted a Bayesian incidence function model extended for dynamic landscapes to snapshot data on five epiphytic lichens among 2083 mapped oaks (dynamic patches). We estimate the age at which trees become suitable patches for different species, which defines their niche breadth (number of suitable trees). We show that the colonization rates were generally low, but increased with increasing connectivity in accordance with metapopulation theory. The rates were related to species traits, and we show, for the first time, that they are higher for species with wide niches and small dispersal propagules than for species with narrow niches or large propagules. We also show frequent long-distance dispersal in epiphytes by quantifying the relative importance of local dispersal and background deposition of dispersal propagules. Local stochastic extinctions from intact trees were negligible in all study species, and thus, the extinction rate is set by the rate of patch destruction (tree fall). These findings mean that epiphyte metapopulations may have slow colonization-extinction dynamics that are explained by connectivity, species traits, and patch dynamics.