The relationship between agricultural intensification and biological control: experimental tests across Europe

Agricultural intensification can affect biodiversity and related ecosystem services such as biological control, but large-scale experimental evidence is missing. We examined aphid pest populations in cereal fields under experimentally reduced densities of (1) ground-dwelling predators (-G), (2) vegetation-dwelling predators and parasitoids (-V), (3) a combination of (1) and (2) (-G-V),compared with open-fields (control), in contrasting landscapes with low vs. high levels of agricultural intensification (AI), and in five European regions. Aphid populations were 28%, 97%, and 199% higher in -G, -V, and -G -V treatments, respectively, compared to the open fields, indicating synergistic effects of both natural-enemy groups. Enhanced parasitoid : host and predator : prey ratios were related to reduced aphid population density and population growth. The relative importance of parasitoids and vegetation-dwelling predators greatly differed among European regions, and agricultural intensification affected biological control and aphid density only in some regions. This shows a changing role of species group identity in diverse enemy communities and a need to consider region-specific landscape management.

Persistent negative effects of pesticides on biodiversity and biological control potential on European farmland

During the last 50 years, agricultural intensification has caused many wild plant and animal species to go extinct regionally or nationally and has profoundly changed the functioning of agro-ecosystems. Agricultural intensification has many components, such as loss of landscape elements, enlarged farm and field sizes and larger inputs of fertilizer and pesticides. However, very little is known about the relative contribution of these variables to the large-scale negative effects on biodiversity. In this study, we disentangled the impacts of various components of agricultural intensification on species diversity of wild plants, carabids and ground-nesting farmland birds and on the biological control of aphids.

Mapping biological to clinical phenotypes during the development (21 days) and resolution (21 days) of experimental gingivitis

Aim: To characterize and map temporal changes in the biological and clinical phenotype during a 21-day experimental gingivitis study. Materials and Methods: Experimental gingivitis was induced over 21 days in healthy human volunteers (n = 56), after which normal brushing was resumed (resolution phase). Gingival and plaque indices were assessed. Gingival crevicular fluid was collected from four paired test and contra-lateral control sites in each volunteer during induction (Days 0, 7, 14 and 21) and resolution (Days 28 and 42) of experimental gingivitis. Fluid volumes were measured and a single analyte was quantified from each site-specific, 30s sample. Data were evaluated by analysis of repeated measurements and paired sample tests. Results: Clinical indices and gingival crevicular fluid volumes at test sites increased from Day 0, peaking at Day 21 (test/control differences all p

A Robust Co-Localisation Measurement Utilising Z-Stack Image Intensity Similarities for Biological Studies

Background: Co-localisation is a widely used measurement in immunohistochemical analysis to determine if fluorescently labelled biological entities, such as cells, proteins or molecules share a same location. However the measurement of co-localisation is challenging due to the complex nature of such fluorescent images, especially when multiple focal planes are captured. The current state-of-art co-localisation measurements of 3-dimensional (3D) image stacks are biased by noise and cross-overs from non-consecutive planes.

Method: In this study, we have developed Co-localisation Intensity Coefficients (CICs) and Co-localisation Binary Coefficients (CBCs), which uses rich z-stack data from neighbouring focal planes to identify similarities between image intensities of two and potentially more fluorescently-labelled biological entities. This was developed using z-stack images from murine organotypic slice cultures from central nervous system tissue, and two sets of pseudo-data. A large amount of non-specific cross-over situations are excluded using this method. This proposed method is also proven to be robust in recognising co-localisations even when images are polluted with a range of noises.

Results: The proposed CBCs and CICs produce robust co-localisation measurements which are easy to interpret, resilient to noise and capable of removing a large amount of false positivity, such as non-specific cross-overs. Performance of this method of measurement is significantly more accurate than existing measurements, as determined statistically using pseudo datasets of known values. This method provides an important and reliable tool for fluorescent 3D neurobiological studies, and will benefit other biological studies which measure fluorescence co-localisation in 3D.

ISOLATION AND PRELIMINARY BIOLOGICAL CHARACTERIZATION OF KPNFIRFAMIDE, A NOVEL FMRFAMIDE-RELATED PEPTIDE FROM THE FREE-LIVING NEMATODE, PANAGRELLUS-REDIVIVUS

A novel FMRFamide-related heptapeptide, Lys-Pro-Asn-Phe-Ile-Arg-Phe-NH2 (KPNFIRFamide), was isolated and characterized from acid ethanol extracts of the free-living nematode, Panagrellus redivivus. Whole-worm extracts contained greater than or equal to 9 pmol KPNFIRFamide/g wet weight. A synthetic replicate of this peptide induced a rapid relaxation of tone and inhibited spontaneous contractility in isolated innervated and denervated body-wall muscle strips of the parasitic nematode, Ascaris suum. KPNFIRFamide (0.1 nM) induced measurable relaxations in 50% of the muscle preparations examined. Concentrations greater than or equal to 0.3 nM induced relaxation in 100% of muscle preparations examined. The relaxation was short-lived at concentrations of peptide greater than or equal to 1 mu M and displayed a profile typical of receptor desensitization. These data suggest the occurrence of a closely related peptide in A. suum and add further evidence to the concept of primary structural conservation of FaRPs within the nematodes.

Biological effectiveness on live cells of laser driven protons at dose rates exceeding 109 Gy/s

The ultrashort duration of laser-driven multi-MeV ion bursts offers the possibility of radiobiological studies at extremely high dose rates. Employing the TARANIS Terawatt laser at Queen's University, the effect of proton irradiation at MeV-range energies on live cells has been investigated at dose rates exceeding 109 Gy/s as a single exposure. A clonogenic assay showed consistent lethal effects on V-79 live cells, which, even at these dose rates, appear to be in line with previously published results employing conventional sources. A Relative Biological Effectiveness (RBE) of 1.4±0.2 at 10% survival is estimated from a comparison with a 225 kVp X-ray source.