Stability of pollination services decreases with isolation from natural areas despite honey bee visits

Sustainable agricultural landscapes by definition provide high magnitude and stability of ecosystem services, biodiversity and crop productivity. However, few studies have considered landscape effects on the stability of ecosystem services. We tested whether isolation from florally diverse natural and semi-natural areas reduces the spatial and temporal stability of flower-visitor richness and pollination services in crop fields. We synthesised data from 29 studies with contrasting biomes, crop species and pollinator communities. Stability of flower-visitor richness, visitation rate (all insects except honey bees) and fruit set all decreased with distance from natural areas. At 1 km from adjacent natural areas, spatial stability decreased by 25, 16 and 9% for richness, visitation and fruit set, respectively, while temporal stability decreased by 39% for richness and 13% for visitation. Mean richness, visitation and fruit set also decreased with isolation, by 34, 27 and 16% at 1 km respectively. In contrast, honey bee visitation did not change with isolation and represented > 25% of crop visits in 21 studies. Therefore, wild pollinators are relevant for crop productivity and stability even when honey bees are abundant. Policies to preserve and restore natural areas in agricultural landscapes should enhance levels and reliability of pollination services.     

Fixed Dystonia in Complex Regional Pain Syndrome: a Descriptive and Computational Modeling Approach

Background  

Complex regional pain syndrome (CRPS) may occur after trauma, usually to one limb, and is characterized by pain and disturbed blood flow, temperature regulation and motor control. Approximately 25% of cases develop fixed dystonia. Involvement of dysfunctional GABAergic interneurons has been suggested, however the mechanisms that underpin fixed dystonia are still unknown. We hypothesized that dystonia could be the result of aberrant proprioceptive reflex strengths of position, velocity or force feedback.     

Natural Variants of Photosystem II Subunit D1 Tune Photochemical Fitness to Solar Intensity

Photosystem II (PSII) is composed of six core polypeptides that make up the minimal unit capable of performing the primary photochemistry of light-driven charge separation and water oxidation in all oxygenic phototrophs. The D1 subunit of this complex contains most of the ligating amino acid residues for the Mn₄CaO₅ core of the water-oxidizing complex (WOC). Most cyanobacteria have 3–5 copies of the psbA gene coding for at least two isoforms of D1, whereas algae and plants have only one isoform. Synechococcus elongatus PCC 7942 contains two D1 isoforms; D1:1 is expressed under low light conditions, and D1:2 is up-regulated in high light or stress conditions. Using a heterologous psbA expression system in the green alga Chlamydomonas reinhardtii, we have measured growth rate, WOC cycle efficiency, and O₂ yield as a function of D1:1, D1:2, or the native algal D1 isoform. D1:1-PSII cells outcompete D1:2-PSII cells and accumulate more biomass in light-limiting conditions. However, D1:2-PSII cells easily outcompete D1:1-PSII cells at high light intensities. The native C. reinhardtii-PSII WOC cycles less efficiently at all light intensities and produces less O₂ than either cyanobacterial D1 isoform. D1:2-PSII makes more O₂ per saturating flash than D1:1-PSII, but it exhibits lower WOC cycling efficiency at low light intensities due to a 40% faster charge recombination rate in the S₃ state. These functional advantages of D1:1-PSII and D1:2-PSII at low and high light regimes, respectively, can be explained by differences in predicted redox potentials of PSII electron acceptors that control kinetic performance.     

Comparing the recovery of richness,structure, and biomass in naturally regrowing and planted reforestation

The clearing of natural vegetation for agriculture has reduced the capacity of natural systems to provide ecosystem functions. Ecological restoration can restore desirable ecosystem functions, such as creating habitat for animal conservation and carbon sequestration as woody biomass. In order to maintain these beneficial ecosystem functions, restoration projects need to mature into self‐perpetuating communities. Here we compared the ecological attributes of two types of restoration, “active” tree plantings with “passive” natural forest regeneration (“natural regrowth”) to existing remnant vegetation in a cleared agricultural landscape. Specifically, we measured differences between forest categories in factors that may predict future restoration failure or ecosystem collapse: aboveground plant biomass and biomass accrual over time (for regrowing stands), plant density and size class distributions, and diversity of functional groups based on seed dispersal and growth strategy traits. We found that natural regrowth and planted forests were similar in many ecological characteristics, including biomass accrual. Despite this, planted stands contained fewer tree recruit and shrub individuals, which may be due to limited recruitment in plantings. If this continues, these forests may be at risk of collapsing into nonforest states after mature trees senesce. Lower shrub density and richness of mid‐story trees may lead to lower structural complexity in planting plots, and alongside lower richness of fleshy‐fruited plant species may reduce animal resources and animal use of the restored stand. In our study region, natural regrowth may result in restored woodland communities with greater conservation and carbon mitigation value.     

Lymphatic filariasis epidemiology in Samoa in 2018: Geographic clustering and higher antigen prevalence in older age groups

BackgroundSamoa conducted eight nationwide rounds of mass drug administration (MDA) for lymphatic filariasis (LF) between 1999 and 2011, and two targeted rounds in 2015 and 2017 in North West Upolu (NWU), one of three evaluation units (EUs). Transmission Assessment Surveys (TAS) were conducted in 2013 (failed in NWU) and 2017 (all three EUs failed). In 2018, Samoa was the first in the world to distribute nationwide triple-drug MDA using ivermectin, diethylcarbamazine, and albendazole. Surveillance and Monitoring to Eliminate LF and Scabies from Samoa (SaMELFS Samoa) is an operational research program designed to evaluate the effectiveness of triple-drug MDA on LF transmission and scabies prevalence in Samoa, and to compare the usefulness of different indicators of LF transmission. This paper reports results from the 2018 baseline survey and aims to i) investigate antigen (Ag) prevalence and spatial epidemiology, including geographic clustering; ii) compare Ag prevalence between two different age groups (5–9 years versus ≥10 years) as indicators of areas of ongoing transmission; and iii) assess the prevalence of limb lymphedema in those aged ≥15 years.MethodsA community-based cluster survey was conducted in 30 randomly selected and five purposively selected clusters (primary sampling units, PSUs), each comprising one or two villages. Participants were recruited through household surveys (age ≥5 years) and convenience surveys (age 5–9 years). Alere Filariasis Test Strips (FTS) were used to detect Ag, and prevalence was adjusted for survey design and standardized for age and gender. Adjusted Ag prevalence was estimated for each age group (5–9, ≥10, and all ages ≥5 years) for random and purposive PSUs, and by region. Intraclass correlation (ICC) was used to quantify clustering at regions, PSUs, and households.ResultsA total of 3940 persons were included (1942 children aged 5–9 years, 1998 persons aged ≥10 years). Adjusted Ag prevalence in all ages ≥5 years in randomly and purposively selected PSUs were 4.0% (95% CI 2.8–5.6%) and 10.0% (95% CI 7.4–13.4%), respectively. In random PSUs, Ag prevalence was lower in those aged 5–9 years (1.3%, 95% CI 0.8–2.1%) than ≥10 years (4.7%, 95% CI 3.1–7.0%), and poorly correlated at the PSU level (R-square = 0.1459). Adjusted Ag prevalence in PSUs ranged from 0% to 10.3% (95% CI 5.9–17.6%) in randomly selected and 3.8% (95% CI 1.3–10.8%) to 20.0% (95% CI 15.3–25.8%) in purposively selected PSUs. ICC for Ag-positive individuals was higher at households (0.46) compared to PSUs (0.18) and regions (0.01).ConclusionsOur study confirmed ongoing transmission of LF in Samoa, in accordance with the 2017 TAS results. Ag prevalence varied significantly between PSUs, and there was poor correlation between prevalence in 5–9 year-olds and older ages, who had threefold higher prevalence. Sampling older age groups would provide more accurate estimates of overall prevalence, and be more sensitive for identifying residual hotspots. Higher prevalence in purposively selected PSUs shows local knowledge can help identify at least some hotspots.     

Effects of exotic species on evolutionary diversification

Exotic species invasions create almost ideal conditions for promoting evolutionary diversification: establishment of allopatric populations in new environmental conditions; altered ecological opportunities for native species; and new opportunities for hybridization between previously allopatric taxa. Here, we review recent studies of the evolutionary consequences of species invasions, revealing abundant and widespread examples of exotic species promoting evolutionary diversification via increased genetic differentiation among populations of both exotic and native species and the creation of new hybrid lineages. Our review indicates that, although the well-documented reductions to biodiversity caused by exotic species might outweigh the increases resulting from diversification, a complete understanding of the net effects of exotic species on biodiversity in the long term will require consideration of both.     

Developing inexpensive malaria vaccines from plants and algae

Malaria is a parasitic, mosquito-borne, infectious disease that threatens nearly half of the global population. The last decade has seen a dramatic drop in the number of malaria-related deaths because of vector control methods and anti-malarial drugs. Unfortunately, this strategy is not sustainable because of the emergence of insecticide-resistant mosquitoes and drug-resistant Plasmodium parasites. Eradication of malaria will ultimately require low-cost easily administered vaccines that work in concert with current control methods. Low cost and ease of administration will be essential components of any vaccine, because malaria endemic regions are poor and often lack an adequate healthcare infrastructure. Recently, several groups have begun addressing these issues using inexpensive photosynthetic organisms for producing vaccine antigens and exploring oral delivery strategies. Immune responses from plant-based injectable malaria vaccines are promising, but attempts to adapt these for oral delivery suggest we are far from a feasible strategy. Here, we review examples of these technologies and discuss the progress and potential of this research, as well as the obstacles ahead.     

North American Lauraceae: Terpenoid Emissions,Relative Attraction and Boring Preferences of Redbay Ambrosia Beetle,Xyleborus glabratus (Coleoptera: Curculionidae: Scolytinae)

The invasive redbay ambrosia beetle, Xyleborus glabratus, is the primary vector of Raffaelea lauricola, a symbiotic fungus and the etiologic agent of laurel wilt. This lethal disease has caused severe mortality of redbay (Persea borbonia) and swampbay (P. palustris) trees in the southeastern USA, threatens avocado (P. americana) production in Florida, and has potential to impact additional New World species. To date, all North American hosts of X. glabratus and suscepts of laurel wilt are members of the family Lauraceae. This comparative study combined field tests and laboratory bioassays to evaluate attraction and boring preferences of female X. glabratus using freshly-cut bolts from nine species of Lauraceae: avocado (one cultivar of each botanical race), redbay, swampbay, silkbay (Persea humilis), California bay laurel (Umbellularia californica), sassafras (Sassafras albidum), northern spicebush (Lindera benzoin), camphor tree (Cinnamomum camphora), and lancewood (Nectandra coriacea). In addition, volatile collections and gas chromatography-mass spectroscopy (GC-MS) were conducted to quantify terpenoid emissions from test bolts, and electroantennography (EAG) was performed to measure olfactory responses of X. glabratus to terpenoids identified by GC-MS. Significant differences were observed among treatments in both field and laboratory tests. Silkbay and camphor tree attracted the highest numbers of the beetle in the field, and lancewood and spicebush the lowest, whereas boring activity was greatest on silkbay, bay laurel, swampbay, and redbay, and lowest on lancewood, spicebush, and camphor tree. The Guatemalan cultivar of avocado was more attractive than those of the other races, but boring response among the three was equivalent. The results suggest that camphor tree may contain a chemical deterrent to boring, and that different cues are associated with host location and host acceptance. Emissions of α-cubebene, α-copaene, α-humulene, and calamenene were positively correlated with attraction, and EAG analyses confirmed chemoreception of terpenoids by antennal receptors of X. glabratus.