Aerial dispersal using silk ('ballooning') has evolved in spiders (Araneae), spider mites (Acari) and in the larvae of moths (Lepidoptera). Since the 17th century, over 500 observations of ballooning behaviours have been published, yet there is an absence of any evolutionary synthesis of these data. In this paper the literature is reviewed, extensively documenting the known world fauna that balloon and the principal behaviours involved. This knowledge is then incorporated into the current evolutionary phylogenies to examine how ballooning might have arisen. Whilst it is possible that ballooning co-evolved with silk and emerged as early as the Devonian (410-355 mya), it is arguably more likely that ballooning evolved in parallel with deciduous trees, herbaceous annuals and grasses in the Cretaceous (135-65 mya). During this period, temporal (e.g. bud burst, chlorophyll thresholds) and spatial (e.g. herbivory, trampling) heterogeneities in habitat structuring predominated and intensified into the Cenozoic (65 mya to the present). It is hypothesized that from the ancestral launch mechanism known as 'suspended ballooning', widely used by individuals in plant canopies, 'tip-toe' and 'rearing' take-off behaviours were strongly selected for as habitats changed. It is contended that ballooning behaviour in all three orders can be described as a mixed Evolutionary Stable Strategy. This comprises individual bet-hedging due to habitat unpredictability, giving an underlying randomness to individual ballooning, with adjustments to the individual ballooning probability being conferred by more predictable habitat changes or colonization strategies. Finally, current methods used to study ballooning, including modelling and genetic research, are illustrated and an indication of future prospects given.

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Summary 1.Several genetically modified herbicide-tolerant (GMHT) crops have cleared most of the regulatory hurdles required for commercial growing in the United Kingdom. However, concerns have been expressed that their management will have negative impacts on farmland biodiversity as a result of improved control given by the new herbicide regimes of the arable plants that support farmland birds and other species of conservation value. 2. The Farm-Scale Evaluations (FSE) project is testing the null hypothesis that there is no difference between the management of GMHT varieties of beet, oilseed rape and maize and that of comparable conventional varieties in their effect on the abundance and diversity of arable plants and invertebrates. The FSE also aims to estimate the magnitude and consider the implications of any differences that are found. 3. The experimental design of the FSE is a randomized block, with two treatments allocated at random to half-fields. The target sample is around 60-75 fields for each crop, selected to represent variation of geography and intensity of management across Britain. The experimental crops are managed by commercial farmers as if under commercial conditions. 4. Biodiversity indicators have been selected from plants and terrestrial invertebrates to identify differences between crop management regimes that may result in important ecological changes over larger scales of space and time. Field sampling is at fixed points, mainly along transects from the field boundary, starting before the crop is sown and continuing into following crops. 5. Synthesis and applications. The FSE is best considered as an investigation into the effects of contrasting crop management regimes on farmland biodiversity, rather than a study of the effects of genetic modification. It could become a model for future studies of ecological effects of the way we use and manage agricultural land.

Summary1. An explicitly spatial sampling approach was employed to test the null hypothesis that the predation on slugs by the carabid beetle Pterostichus melanarius (Illiger) was opportunistic. 2. The beetles and slugs were sampled across a nested series of grids of sampling points, in a ®eld of winter wheat during June and July 1997. 3. The spatial distribution of all slugs in June was found to change with the scale of the sampling grid, from random on the 0.25 m scale, through aggregation at 1 m, to random at 4 m. At the highest scale of 16 m, the slugs were signi®cantly spatially aggregated. 4. The distribution of beetles in June was also spatially dynamic, with randomness observed at the 4 m and 8 m scales. At 16 m, signi®cant aggregation was observed. 5. The dynamic distributions of slugs and beetles, at 16 m, were found not to be associated with, and thus were not determined by, soil or crop factors. 6. Comparison of slug and beetle populations showed, however, that the distributions at 16 m were dynamically associated with each other. In June where there were many slugs there were also many carabids, whilst in July where there were many carabids there were few slugs. 7. Approximately 11% of the beetles sampled across the 16 m grid in June and July were found to have ingested slug protein, following intensive enzyme-linked immunosorbent assay (ELISA) testing. 8. The spatial distribution of these slug-positive beetles was signi®cantly associated with the distribution of the larger slug classes, over 25 mg. Where there were many large slugs in June there were many slug-positive beetles. Conversely, in July few large slugs were found where there were many slug-positive beetles. 9. Parametric analysis revealed that these changes in the large slug class, at each sampling point between June and July (growth), were negatively related to the local numbers of slug-positive beetles, and that growth declined as the local numbers of beetles increased. 10. These ®ndings suggest that predation was not opportunistic, but direct and dynamic, falsifying the null hypothesis. Moreover, this predation elicited signi®cant changes in the spatial distribution and local density of the slugs, in a manner that may be termed spatially density dependent.

We foresee a new global-scale, ecological approach to biomonitoring emerging within the next decade that can detect ecosystem change accurately, cheaply, and generically. Next-generation sequencing of DNA sampled from the Earth's environments would provide data for the relative abundance of operational taxonomic units or ecological functions. Machine-learning methods would then be used to reconstruct the ecological networks of interactions implicit in the raw NGS data. Ultimately, we envision the development of autonomous samplers that would sample nucleic acids and upload NGS sequence data to the cloud for network reconstruction. Large numbers of these samplers, in a global array, would allow sensitive automated biomonitoring of the Earth's major ecosystems at high spatial and temporal resolution, revolutionising our understanding of ecosystem change.

We evaluated the effects of the herbicide management associated with genetically modified herbicide-tolerant (GMHT) winter oilseed rape (WOSR) on weed and invertebrate abundance and diversity by testing the null hypotheses that there is no difference between the effects of herbicide management of GMHT WOSR and that of comparable conventional varieties. For total weeds, there were few treatment differences between GMHT and conventional cropping, but large and opposite treatment effects were observed for dicots and monocots. In the GMHT treatment, there were fewer dicots and monocots than in conventional crops. At harvest, dicot biomass and seed rain in the GMHT treatment were one-third of that in the conventional, while monocot biomass was threefold greater and monocot seed rain almost fivefold greater in the GMHT treatment than in the conventional. These differential effects persisted into the following two years of the rotation. Bees and Butterflies that forage and select for dicot weeds were less abundant in GMHT WORS management in July. Year totals for Collembola were greater under GMHT management. There were few other treatment effects on invertebrates, despite the marked effects of herbicide management on the weeds.

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Summary1. Assuring future food productivity and security will require that better use is made of pest regulation provided by naturally occurring ecological services. However, empirical evidence of large-scale regulatory effects that might be employed in agriculture is still relatively scarce. 2. Using data from 257 conventionally managed arable fields at the UK national scale, we examine whether changes in the long-term store of weed seed in the seedbank are consistent with regulation by seed predatory carabid beetles. 3. We test three expectations of a simple conceptual model for carabid seed predation. The relationships we estimate are consistent with the model and suggest that carabid predation of weed seeds shed onto the soil surface changes the amount of seed returned to the seedbank bringing about seedbank change and regulation. 4. Granivorous and omnivorous carabids regulated seedbank abundance, with effects being observed on monocotyledon seedbank abundance, in all crops, and on total seedbank abundance, in spring maize and winter oilseed rape; effects that were robust across fields with differing pesticide management and between regions of the UK. 5. We found evidence of density dependence, with increasing amounts of seed rain leading to stronger regulation of the seedbank. 6. Our results also suggest that correlations between seed predators and seed rain abundance, which might be used to infer important effects of seed predators, do not provide sufficient evidence to indicate regulation of the weed seedbank. 7. Synthesis and applications. A major challenge for the future is to manage ecological, pest control services in place of current pesticides with little or no additional risk to productivity and food security. Our work shows that carabid seed predators have regulatory effects on the seedbank that appear general and robust across a range of current cropping and farm management situations at the national scale. Environmental Stewardship methods already exist across Europe to enhance carabid numbers in farmland. This means that carabid seed predators fit within a working framework that could be used to promote integrated pest management alongside or even in place of herbicides.