Most insects carry specialised bacteria that dwell permanently inside them. These bacteria are known as symbionts and may be beneficial or costly to their insect host. In this project, we will investigate a bacterial symbiont, Spiroplasma, that is able to manipulate host insect reproduction to its own advantage. Like many insect symbionts, Spiroplasma is predominantly transmitted from female insects to their offspring. Because males cannot transmit the bacteria, they are essentially an evolutionary 'dead end' from the perspective of the symbiont. Symbionts are therefore under selection to increase the proportion of female offspring, and the result is a diversity of symbiont-induced reproductive manipulation strategies. Spiroplasma employs one of the most straightforward: male offspring carrying the symbiont die before adulthood (usually in the egg stage). This is assumed to benefit the surviving sisters, although the advantages are not always clear. In addition to maternal transmission, symbionts can occasionally be transmitted between unrelated individuals, either within or between species. This 'horizontal' transmission is evolutionarily important because it is a route for heritable characteristics to be passed across species boundaries in animals. However, since such transfers are rare in nature, we know little about the process. In this project, we will study two closely-related groups of Spiroplasma, infecting ladybirds and aphids respectively, in order to ask what happens when symbionts move between distantly-related insects. First, we will sequence the genomes of 13 strains of Spiroplasma bacteria: three from different species of ladybirds, and 10 from the pea aphid. The pea aphid strains will include bacteria causing complete, partial and no death of male offspring. We will use the genomes to look for similarities and differences among the Spiroplasma strains in the putative genetic mechanism for male-killing. We also aim to identify the genetic variation that drives the phenotypic differences in male-killing seen among the aphid Spiroplasma. In the second part of the project, we will recreate a likely route of symbiont transmission. Ladybirds are well-known as predators of aphids, and it is highly plausible that this predator-prey relationship allowed transmission of Spiroplasma between the two groups in their evolutionary past. We will carry out microinjection of body fluid containing male-killing Spiroplasma from aphids to ladybirds, and vice versa. We will test whether a new heritable infection is established and if the new infections cause male-killing. Our study combines an ambitious plan to recreate cross-species symbiont transmission with a detailed understanding of mechanism through symbiont genome sequencing. Ladybirds and aphids present a great opportunity to understand horizontal acquisition of traits via horizontal transmission of symbionts, and also to investigate the barriers that may stand in the way of that transfer. By gaining a full picture of symbiont function and transmission in the context of one specific predator-prey interaction, we will open the way to answer further questions surrounding the acquisition of novel symbionts, and the evolution of symbiont-mediated effects. Insects are an extraordinary evolutionary success story. Hidden inside insects, bacterial symbionts play important roles in nutrition, defence and reproduction. Explaining how and why new symbiotic associations arise is therefore a vital element for understanding insect evolution, and is the overarching aim of the project we propose.

To design the molecular architecture of polymer chains for desired processing performance, a highly interdisciplinary effort will be required which incorporates experts in experimental and theoretical rheology, polymer processing, polymerization kinetics and catalysts, and polymer synthesis and characterization (this expertise cannot be found in any one location). Scientists from four U.S. universities (with expertise in non-linear rheology, flow birefringence, polymer processing and molecular rheology) will join forces with scientists from seven English universites and one from Holland to attack this problem. The research effort will capitalize on the Leeds-based Microscale Polymer Processing (MuPP) consortium with main contributions from Leeds (molecular rheology, reaction kinetics), Durham (anionic chemistry). The group at Imperial College, London is joining this co-operative programme with expertise in polymerization catalyst development for tailored molecular structure. The approach is to use model systems to establish a rheological standard by which to identify the structures present in commercially produced PE's and then develop correlations between polymerization kinetics, molecular architecture and processing performance.

Plastics are moving into the 21st century! A new generation of materials will be designed, not only in the shape and form of their components, but right down at the level of the molecules themselves. UK groups in chemistry, physics, maths and engineering have been working to find out the best way to join up the long string-like molecules of plastics like polyethylene (PE) to help smooth the path of their processing. In the hot melted state their flow is not only liquid but also elastic. This feature needs to be carefully controlled by molecular design. Several US groups have been working with PE made by new catalysts that may be able to deliver the ideal molecular structures. This proposal is to join up these two leading collaborations to fast-track the new materials.

To design the molecular architecture of polymer chains for desired processing performance, a highly interdisciplinary effort will be required which incorporates experts in experimental and theoretical rheology, polymer processing, polymerization kinetics and catalysts, and polymer synthesis and characterization (this expertise cannot be found in any one location). Scientists from two U.S. universities (with expertise in non-linear rheology, polymer processing and anionic synthesis) will join forces with scientists from seven English universites and one from Holland to attack this problem. The research effort will capitalize on the Leeds-based Microscale Polymer Processing (MuPP) consortium with main contributions from Leeds (molecular rheology, reaction kinetics), Durham (anionic chemistry). The group at Imperial College, London is joining this co-operative programme with expertise in polymerization catalyst development for tailored molecular structure. The approach is to use model systems to establish a rheological standard by which to identify the structures present in commercially produced PE's and then develop correlations between polymerization kinetics, molecular architecture and processing performance.

Communities of plants, insect herbivores, and their insect parasitoid enemies provide most of the known species on Earth. These communities include interactions that lead to economic damage, such as pests of crops, and others that benefit human societies, such as biocontrol agents. Despite their importance, we still know little about what determines which species eat, or are eaten by, other species. We know most about links between plants and herbivores, less about herbivores and parasitoids, and less again about patterns over all three levels combined. A key question is the extent to which such three level (tritrophic) species associations are structured from the 'bottom-up' by plant traits, from the 'top-down' by parasitoids, or some combination of these. The 'bottom-up' view regards herbivore-parasitoid interactions as structured by processes happening a trophic level lower, via the effects of plants on herbivores. In contrast, the 'top-down' view sees parasitoid-herbivore interactions as driving the evolution of herbivore defences, and these traits as more important for structuring parasitoid communities than the host plants on which they are found. This project assesses the evidence for these alternative models, and their combinations, using state of the art statistical methods that require three types of data: (i) an interaction matrix, summarising links between species in one trophic level and those in another; (ii) herbivore defence trait data and (iii) complete species-level phylogenies for plants, herbivores and their parasitoids. Finding that plant phylogeny is a strong predictor of both plant-herbivore and herbivore-parasitoid interactions would support the bottom-up view. In contrast, finding that herbivore-parasitoid interactions are strongly predicted by herbivore defensive traits would support a top-down view. First, we will estimate the effects of species identity and traits on plant-herbivore and herbivore-parasitoid interactions, providing the first test of the relative importance of bottom-up versus top-down processes. We will use over 50,000 records of specific plant-herbivore-parasitoid interactions for natural communities comprising trees, gallwasp herbivores, and chalcid parasitoids, sampled from three regional datasets that span the Northern Hemisphere. These communities have evolved independently for long enough to provide largely independent tests of our hypotheses. Second, we ask whether herbivores in our three regional communities have independently evolved similar sets of defences. If top-down effects are strong, and herbivore defences target fundamental aspects of parasitoid attack behaviour, then selection should favour the repeated evolution of similar sets of defensive traits. Gallwasp herbivores live inside galls, complex novel plant tissues whose development the larval wasps induce. Parasitoids all attack gallwasps by drilling through gall tissues, and previous work suggests that some gall traits (such as coatings of spines or sticky resins) have evolved to make this more difficult. Our hypothesis is that such gall traits will both structure parasitoid communities and have evolved repeatedly. Finally, we will assess how well our statistical models predict which parasitoids attack a novel or unsampled gallwasp herbivore when all we know about it are which plant it is on, which gall traits it has, and how it is related to other gallwasps. Our approach involves making model-based predictions for gallwasp-parasitoid interactions for which we have real data, so that via cross-validation we can assess the accuracy (i.e. whether predictions are unbiased) and precision (i.e. whether predictions are made with high confidence) of our model. This approach could be of particular value in predicting the natural enemies of emerging pests and the non-target victims of natural enemies, and we will apply it to predicting the enemies attacking oriental chestnut gallwasp, a global pest species.