Manu E. Saunders

A global synthesis of the effects of diversified farming systems on arthropod diversity within fields and across agricultural landscapes

Agricultural intensification is a leading cause of global biodiversity loss, which can reduce the provisioning of ecosystem services in managed ecosystems. Organic farming and plant diversification are farm management schemes that may mitigate potential ecological harm by increasing species richness and boosting related ecosystem services to agroecosystems. What remains unclear is the extent to which farm management schemes affect biodiversity components other than species richness, and whether impacts differ across spatial scales and landscape contexts. Using a global metadataset, we quantified the effects of organic farming and plant diversification on abundance, local diversity (communities within fields), and regional diversity (communities across fields) of arthropod pollinators, predators, herbivores, and detritivores. Both organic farming and higher in-field plant diversity enhanced arthropod abundance, particularly for rare taxa. This resulted in increased richness but decreased evenness. While these responses were stronger at local relative to regional scales, richness and abundance increased at both scales, and richness on farms embedded in complex relative to simple landscapes. Overall, both organic farming and in-field plant diversification exerted the strongest effects on pollinators and predators, suggesting these management schemes can facilitate ecosystem service providers without augmenting herbivore (pest) populations. Our results suggest that organic farming and plant diversification promote diverse arthropod metacommunities that may provide temporal and spatial stability of ecosystem service provisioning. Conserving diverse plant and arthropod communities in farming systems therefore requires sustainable practices that operate both within fields and across landscapes.

Almond orchards with living ground cover host more wild insect pollinators

Wild pollinators are becoming more valuable to global agriculture as the commercial honeybee industry is increasingly affected by disease and other stressors. Perennial tree crops are particularly reliant on insect pollination, and are often pollen limited. Research on how different tree crop production systems influence the richness and abundance of wild pollinators is, however, limited. We investigated, for the first time, the richness and abundance of potential wild pollinators in commercial temperate almond orchards in Australia, and compared them to potential pollinator communities in proximate native vegetation. We quantified ground cover variables at each site and assessed the value of ground cover on the richness and abundance of potential wild pollinators in commercial almond systems focussing on three common taxa: bees, wasps and flies. More insects were caught in orchards with living ground cover than in native vegetation or orchards without ground cover, although overall species richness was highest in native vegetation. Percent ground cover was positively associated with wasp richness and abundance, and native bee richness, but flies showed no association with ground cover. The strongest positive relationship was between native bee abundance and the richness of ground cover plants. Our results suggest that maintaining living ground cover within commercial almond orchards could provide habitat and resources for potential wild pollinators, particularly native bees. These insects have the potential to provide a valuable ecosystem service to pollinator-dependent crops such as almond.

Pollinators, pests, and predators: Recognizing ecological trade-offs in agroecosystems

Ecological interactions between crops and wild animals frequently result in increases or declines in crop yield. Yet, positive and negative interactions have mostly been treated independently, owing partly to disciplinary silos in ecological and agricultural sciences. We advocate a new integrated research paradigm that explicitly recognizes cost-benefit trade-offs among animal activities and acknowledges that these activities occur within social-ecological contexts. Support for this paradigm is presented in an evidence-based conceptual model structured around five evidence statements highlighting emerging trends applicable to sustainable agriculture. The full range of benefits and costs associated with animal activities in agroecosystems cannot be quantified by focusing on single species groups, crops, or systems. Management of productive agroecosystems should sustain cycles of ecological interactions between crops and wild animals, not isolate these cycles from the system. Advancing this paradigm will therefore require integrated studies that determine net returns of animal activity in agroecosystems.

Spatial and temporal variation in pollinator community structure relative to a woodland–almond plantation edge

Agricultural landscape elements, such as field edges, are not always a barrier to insects but can influence their distribution and dispersal behaviour. The present study investigated spatial and temporal patterns in wild pollinator (fly, wasp and non‐Apis bee) distribution across an edge between natural mallee woodland and monoculture almond plantations in southern Australia, during the critical almond flowering period. This is the first study of variation in pollinator community distribution on both sides of an edge between natural vegetation and flowering tree crop plantations. Species richness, diversity and evenness (SHE) analysis was also used to identify changes in pollinator community structure relative to the edge. It is shown that the spatial distribution and structure of pollinator communities can vary across a habitat edge with an abrupt temporal changes in resources. Our results suggest that the plantation edge did not prevent wild pollinators spilling over from woodlands, although vegetation homogeneity and phenological changes in resources most likely influenced the dispersal of pollinators into plantation interiors. The findings of the present study contribute to our knowledge of edge responses by insects in managed landscapes and could motivate growers to adopt ecological management practices in commercial plantations. Future studies of insects near farmland edges should include samples on both sides of the edge and should also consider the landscape context.

Cost-benefit trade-offs of bird activity in apple orchards

Birds active in apple orchards in south–eastern Australia can contribute positively (e.g., control crop pests) or negatively (e.g., crop damage) to crop yields. Our study is the first to identify net outcomes of these activities, using six apple orchards, varying in management intensity, in south–eastern Australia as a study system. We also conducted a predation experiment using real and artificial codling moth (Cydia pomonella) larvae (a major pest in apple crops). We found that: (1) excluding birds from branches of apple trees resulted in an average of 12.8% more apples damaged by insects; (2) bird damage to apples was low (1.9% of apples); and (3) when trading off the potential benefits (biological control) with costs (bird damage to apples), birds provided an overall net benefit to orchard growers. We found that predation of real codling moth larvae was higher than for plasticine larvae, suggesting that plasticine prey models are not useful for inferring actual predation levels. Our study shows how complex ecological interactions between birds and invertebrates affect crop yield in apples, and provides practical strategies for improving the sustainability of orchard systems.

Honey bees: the queens of mass media, despite minority rule among insect pollinators

Pollination is a critical ecosystem function with high ecological and economic value. Conservation initiatives aimed at protecting diverse pollinator communities in natural and agricultural habitats are essential, but the implementation and success of such initiatives often depends on public support. Mass media play an important role in building public awareness around environmental issues, and biased coverage can have damaging effects. Here, we present the first analysis of how Australian mainstream media present the ‘pollinator’ paradigm. We gathered insect pollinator and pollination related articles from major Australian online newspapers published over a period of 9 years, and performed a qualitative content analysis using deductive coding to record information on the pollinator species or groups discussed in the story. We found 151 stories, and demonstrate that within these, there was a disproportionate focus on introduced European honey bees as the most important, or only, pollinator insect relevant to Australia. Only 15% of stories mentioned native bees as pollinators and 17% mentioned non‐bee pollinators. There is potential that the trend we report here for pollinators may be indicative of a larger overall simplification and neglect of biodiversity concepts in mainstream media, both in Australia and globally. As public awareness of science and environmental issues partly depend on disseminating accurate information beyond the scholar network, it is imperative that the broader effects of inaccurate science communication are fully understood.

Resource connectivity for beneficial insects in landscapes dominated by monoculture tree crop plantations

Homogenization of agricultural landscapes affects ecological processes and biodiversity and can affect the community composition of ecosystem service providers. These effects can have particular impact in landscapes dominated by monocultures of pollinator-dependent tree crop plantations, which create both spatial and temporal homogeneity at the landscape scale. I looked for associations between the proportion of nearby unmanaged vegetation and potential wild pollinator groups collected within flowering almond orchards in two types of landscape. In the Complex landscape, characterized by a heterogeneous mosaic of multiple crops, semi-natural grassland and natural woodland, insect pollinator groups were not associated with unmanaged vegetation. In the Simple landscape, dominated by monoculture almond plantations, most pollinator groups showed positive relationships with the two unmanaged vegetation types (grassland and woodland). In particular, all wild bee and all but one hoverfly individual were found in remnant native vegetation patches within almond plantations, rather than within rows of almond trees. More research is necessary to identify how structural differences created in monoculture landscapes, between crops and the native vegetation they encroach on, influence ecological communities and the provision of ecosystem services.

The role of avian scavengers in the breakdown of carcasses in pastoral landscapes

ABSTRACT Scavenging birds can provide ecosystem services to pastoralists by contributing to the breakdown of animal carcasses that can harbour and spread disease. However, these benefits have yet to be quantified in Australia. We monitored rabbit carcasses using motion-sensor cameras to identify beneficial avian scavengers across four landscape types (forest, riparian, fields with large isolated trees, and open fields) on a pastoral property in north-central Victoria. We quantified the ecosystem service of carcass breakdown by measuring the per cent weight loss of carcasses exposed to scavenging birds compared to carcasses excluded from birds. Seven of the twenty-four bird-accessible carcasses were attacked by raptors in 2014, and three in 2015. When a raptor attacked a carcass, there was a significantly higher median per cent weight loss of the carcass (16.67%, interquartile range (IQR) = 8.33–100.0) compared with sites where no bird attacks occurred (6.65%, IQR = 3.03–12.06). Our results indicate that raptors are major contributors to carcass breakdown in grazing landscapes and may potentially contribute to reducing the spread of diseases such as blowfly strike and leptospirosis. Maintaining key habitat features for these species (e.g. large isolated trees) is essential for raptor conservation and maximising the ecosystem services they provide.

Combining Costs and Benefits of Animal Activities to Assess Net Yield Outcomes in Apple Orchards

Diverse animal communities influence ecosystem function in agroecosystems through positive and negative plant-animal interactions. Yet, past research has largely failed to examine multiple interactions that can have opposing impacts on agricultural production in a given context. We collected data on arthropod communities and yield quality and quantity parameters (fruit set, yield loss and net outcomes) in three major apple-growing regions in south-eastern Australia. We quantified the net yield outcome (accounting for positive and negative interactions) of multiple animal activities (pollination, fruit damage, biological control) across the entire growing season on netted branches, which excluded vertebrate predators of arthropods, and open branches. Net outcome was calculated as the number of undamaged fruit at harvest as a proportion of the number of blossoms (i.e., potential fruit yield). Vertebrate exclusion resulted in lower levels of fruit set and higher levels of arthropod damage to apples, but did not affect net outcomes. Yield quality and quantity parameters (fruit set, yield loss, net outcomes) were not directly associated with arthropod functional groups. Model variance and significant differences between the ratio of pest to beneficial arthropods between regions indicated that complex relationships between environmental factors and multiple animal interactions have a combined effect on yield. Our results show that focusing on a single crop stage, species group or ecosystem function/service can overlook important complexity in ecological processes within the system. Accounting for this complexity and quantifying the net outcome of ecological interactions within the system, is more informative for research and management of biodiversity and ecosystem services in agricultural landscapes.

Bee conservation: Key role of managed bees

In their Perspective “Conserving honey bees does not help wildlife” (26 January, p. [392][1]), J. Geldmann and J. P. Gonzalez-Varo argue that because managed honey bees are an agricultural animal, their crop pollination does not fit the definition of an ecosystem service. This distinction, the