Biological control of leatherjackets using insect pathogens OF0116T

Leatherjackets (Tipula spp.; larvae of crane flies) are significant pests affecting the organic farming sector. Effective non-chemical methods of protecting organic crops from leatherjackets have not yet been developed, although insect pathogens are a promising method for biological control of these pests. This study will aim to identify and evaluate fungi, nematodes and the bacterium Bacillus thuringiensis for their effectiveness as control agents. The pathogens will be sourced from the HRI resource collection. Selected isolates of pathogens with known activity to dipteran pests will be screened in bioassays against laboratory-reared leatherjackets. Virulent isolates will be examined in detail both in laboratory experiments and glasshouse trials on a cereal and a field vegetable. Feeding behaviour of the pests will be studied in order to develop a rational strategy for application of the microbial control agents, and the effect of temperature on the virulence of control microbes (including cold-tolerant nematodes) will be examined. The incidence of insect pathogenic nematodes and fungi in a population of leatherjackets from an organic farm will be recorded. Replicated field experiments with microbial control agents will be conducted at HDRA under appropriate organic crop production systems using relevant methods developed in other, related MAFF-funded projects. Findings of the study will be published in refereed journals and grower-related information made available at HRI and HDRA and open days, and through the trade press

Theory of amorphous ices

We derive a phase diagram for amorphous solids and liquid supercooled water and explain why the amorphous solids of water exist in several different forms. Application of large-deviation theory allows us to prepare such phases in computer simulations. Along with nonequilibrium transitions between the ergodic liquid and two distinct amorphous solids, we establish coexistence between these two amorphous solids. The phase diagram we predict includes a nonequilibrium triple point where two amorphous phases and the liquid coexist. While the amorphous solids are long-lived and slowly-aging glasses, their melting can lead quickly to the formation of crystalline ice. Further, melting of the higher density amorphous solid at low pressures takes place in steps, transitioning to the lower density glass before accessing a nonequilibrium liquid from which ice coarsens.Comment: revision following review comment

Constrained dynamics of localized excitations causes a non-equilibrium phase transition in an atomistic model of glass formers

Dynamic facilitation theory assumes short-ranged dynamic constraints to be the essential feature of supercooled liquids and draws much of its conclusions from the study of kinetically constrained models. While deceptively simple, these models predict the existence of trajectories that maintain a high overlap with their initial state over many structural relaxation times. We use molecular dynamics simulations combined with importance sampling in trajectory space to test this prediction through counting long-lived particle displacements. For observation times longer than the structural relaxation time exponential tails emerge in the probability distribution of this number. Reweighting trajectories towards low mobility corresponds to a phase transition into an inactive phase. While dynamics in these two phases is drastically different structural measures show only slight differences. We discuss the choice of dynamic order parameter and give a possible explanation for the microscopic origin of the effective dynamic constraints.Comment: revised versio