Now showing 1 - 9 of 9
  • Publication
    A Systematic Review of the Benefits and Costs of Bird and Insect Activity in Agroecosystems
    (Springer Netherlands, 2015)
    Peisley, Rebecca K
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    Luck, Gary W
    Wild fauna occur in every agroecosystem and their interactions with crops can influence yields positively or negatively. Research on the impact of fauna activity on agricultural production focuses mostly on either the costs (e.g. crop damage) or benefits (e.g. pollination) of this activity, with few studies addressing cost-benefit trade-offs in the same context. This has resulted in an incomplete understanding of the implications of fauna activity in agroecosystems. Through a systematic review of the literature, we connect disparate studies to promote a more holistic approach to research on wild fauna in agriculture. We identified 281 studies that quantified a cost and/or benefit of fauna activity in crop systems. Overall, 53.0 % of studies examined the costs of insect and/or bird activity, 37.7 % of studies examined benefits and just 9.3 % of studies covered both costs and benefits of insect and/or bird activity simultaneously. Most birds studied were omnivorous (44.8 %), granivorous (29.0 %) or insectivorous (16.6 %), while insect studies focused on pollinators (42.2 %) or borers (17.5 %). There were clear geographic patterns for studies, with a bias towards studies of the costs of bird activity in North America and studies of benefits in Central America/Caribbean. Most studies on benefits occurred in perennial crops and most cost studies in annual crops. Our results highlight the disjointed nature of research into the cost–benefit trade-offs of fauna activity, and it is essential that future studies examine these trade-offs in order to develop sustainable agricultural strategies that limit production losses while maximising the delivery of ecosystem services from fauna.
  • Publication
    Pollinators, pests, and predators: Recognizing ecological trade-offs in agroecosystems
    (Springer Netherlands, 2016) ;
    Peisley, Rebecca K
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    Luck, Gary W
    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.
  • Publication
    The role of avian scavengers in the breakdown of carcasses in pastoral landscapes
    (Taylor & Francis Australasia, 2017)
    Peisley, Rebecca K
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    Robinson, Wayne A
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    Luck, Gary W
    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.
  • Publication
    Almond orchards with living ground cover host more wild insect pollinators
    (Springer Netherlands, 2013) ;
    Luck, Gary W
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    Mayfield, Margaret M
    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.
  • Publication
    Spatial and temporal variation in pollinator community structure relative to a woodland-almond plantation edge
    (Wiley-Blackwell Publishing Ltd, 2014) ;
    Luck, Gary W
    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.
  • Publication
    Combining Costs and Benefits of Animal Activities to Assess Net Yield Outcomes in Apple Orchards
    (Public Library of Science, 2016) ;
    Luck, Gary W
    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.
  • Publication
    Providing perches for predatory and aggressive birds appears to reduce the negative impact of frugivorous birds in vineyards
    (CSIRO Publishing, 2017)
    Peisley, Rebecca K
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    Luck, Gary W
    Context: Birds active in vineyards in south-eastern Australia can reduce or enhance crop yields via their foraging activities (e.g. by consuming grapes or by preying on grape-eating species). Aims: We examined the effectiveness of artificial perches in encouraging predatory birds into vineyards to scare frugivorous birds and consequently reduce the damage they cause to grapes. Methods: We monitored 12 artificial perches for 4 months during the growing season, spread over six vineyards in north-eastern Victoria, and compared bird damage to grapes at these sites with control sites without perches. Key results: We found that raptors did not use the artificial perches. However, the large and aggressive Australian magpie (Cracticus tibicen) commonly used perches and we recorded 38 513 perch visits by this species. Grapevines around perch sites suffered >50% less grape damage (4.13% damage per bunch) than control sites (8.57% damage per bunch). Conclusions: Our results suggest that providing artificial perches in vineyards can play a role in reducing frugivore damage to grapes. However, the effectiveness of perches can vary under different environmental conditions and certain perch types are not suitable for all predatory or aggressive birds. Implications: Future research should focus on the potential role of large-bodied and competitively aggressive species such as the Australian magpie in altering the activity of smaller frugivorous birds in vineyards, and also on the optimum height and location of artificial perches within vineyards to increase visitation by other predatory or aggressive bird species.
  • Publication
    Pan trap catches of pollinator insects vary with habitat
    (John Wiley & Sons, Inc, 2012) ;
    Luck, Gary W
    Coloured pan trapping is a simple and efficient method for collecting flying insects, yet there is still discussion over the most effective bowl colour to use for particular target groups (e.g. pollinator insects). The success of particular colours can vary across bioregions and habitats. Most published pan trap studies have been conducted in the northern hemisphere, and very few investigated the effects of habitat on pan trap catches. Our study is one of the first to (1) sample for potential pollinators in Australian mallee vegetation and almond orchards and (2) investigate whether habitat interacts with trap colour to influence pan trap catches. We sampled Hymenoptera and Diptera using yellow, white and blue pan traps in native mallee vegetation and two types of managed almond orchards (monoculture and plant-diverse) in the Murray Mallee bioregion of north-western Victoria, Australia. Yellow traps caught the most insects across all habitats, although catches in each colour trap varied with habitat. For all insect groups combined, blue traps caught more individuals in mallee habitats than in almond orchards. For native hymenopterans, yellow traps caught more individuals in plant-diverse orchards than in native sites, while blue traps caught more individuals in native sites. Our results highlight the importance of considering the habitat of individual pan trapping surveys, as no one trap colour is likely to be suitable for trapping target insects across all habitats.
  • Publication
    Cost-benefit trade-offs of bird activity in apple orchards
    (PeerJ, Ltd, 2016)
    Peisley, Rebecca K
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    Luck, Gary W
    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.