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Tropical soils are prone to rapid degradation if not managed well, and agroforestry systems have the potential to restore degraded soils and support agricultural production together with other ecosystem services. In Brazil, an increasing number of pioneering farmers are establishing agroforestry systems on previously cleared farmland. However, while there are a wide range of agroforestry systems, this diversity has hardly been quantified, and it is not clear how these systems differ in their capacity for nutrient cycling to reverse soil degradation. The objectives of the study were to assess innovative agroforestry systems in terms of taxonomic and functional diversity, spatial structure and management, and to assess how these systems differ in terms of structural complexity and their potential for nutrient cycling. We assessed a LiDAR-derived stand structural complexity index (SSCI), interrow spacing, stem density, tree species richness and diversity, community weighted means (CWM) of foliar nitrogen and wood density, livestock density, pruning and mowing regimes in 30 agroforestry systems in the state of São Paulo, Brazil. We used N, P, K, Ca and Mg stocks in litter as a proxy for nutrient cycling. The agroforestry systems could be broadly categorized into silvopastures, multistrata and successional agroforestry systems. These types spanned a gradient of structural complexity, and this complexity was positively associated with tree species richness and planting density. Litter nutrient stocks were positively associated with pruning and mulching, and negatively associated with CWM of wood density, indicating the importance of pioneer trees. Overall, our results suggest that densely planted, pruned agroforestry systems that contain high species richness, including pioneer trees, contain relatively high amounts of N, P, K, Ca and Mg in their litter. These findings provide insight in the key characteristics of agroforestry systems to support nutrient cycling, and can

Intensive agriculture for food and feed production is a key driver of global biodiversity loss. It is generally assumed that more extensive practices are needed to reconcile food production with biodiversity conservation. In a literature review across biomes and for seven taxa, we retrieved 35 alternative practices (e.g. no-tillage, cover crops, organic fertilizer) from 331 studies. We found that no single practice enhanced all taxonomic groups, but that overall less intensive agricultural practices are beneficial to biodiversity. Nevertheless, often practices had no effects observed and very rarely contrasting impacts on aboveground versus belowground taxa. Species responses to practices were mostly consistent across biomes, except for fertilization. We conclude that alternative practices generally enhance biodiversity, but there is also variation in impacts depending on taxonomic group or type of practice. This suggests that a careful selection of practices is needed to secure biodiversity across taxa in future food systems worldwide.

Korla fragrant pear (Pyrus sinkiangensis Yü) depends on cross-pollination by honeybees (Apis mellifera) but may suffer from low honeybee visitation. We assessed whether honeybee abundance and visitation frequency are enhanced by using synthetic Nasonov gland pheromone (NGP), which is naturally produced by worker bees to stimulate the aggregation of bees to food resources or nesting sites. The response of honeybees to synthetic NGP was firstly assessed using Y-tube olfactometer tests in the laboratory, and subsequently in the field, by placing NGP lures on Korla fragrant pear trees in orchards with and without beehives. Honeybee abundance was assessed using coloured pan traps while honeybee visits were assessed by visual observations on pear flowers. Y-tube olfactometer tests showed a significant preference of honeybees for NGP. In pear orchards with beehives, honeybee abundance was 2.5-fold higher on trees with NGP lures than on trees without NGP, and 2.2-fold higher in orchards in which all trees contained NGP lures than in orchards without NGP lures. Such positive effects were not observed in orchards without beehives. Flower visitation by honeybees was significantly higher in trees with NGP lures than without NGP lures, irrespective of the presence (5.7-fold higher) or absence of beehives (27.6-fold higher). In mixed pear-apricot orchards, honeybee abundance was higher in pear trees with NGP lures than without lures. Our results show that NGP lures attract honeybees to flowering pear trees in monoculture pear and mixed pear-apricot orchards, and that this effect is greatest in orchards with beehives.

Loss of arthropod biodiversity can impair the provision of ecosystem services in agricultural landscapes. Crop diversification strategies offer the possibility to support arthropod communities without putting aside agricultural land as conservation areas. Within-field crop diversification measures, such as strip cropping and crop mixtures, may provide arthropods with continuity and diversity in food, shelter and habitat at fine spatial and temporal resolutions. However, it is unclear how strip cropping and plant species diversity within strips influences aerial arthropod and weed communities in commercially sized arable fields. In this 2-year study we tested the effects of crop heterogeneity on aerial arthropod and plant communities in organically managed strip fields. We tested effects of configurational crop heterogeneity by comparing sole cropping (MONO) with strip cropping (STRIP), and compositional crop heterogeneity by comparing STRIP with flower-legume-grain crop mixtures grown in strips (STRIPMIX). Aerial arthropod communities were assessed in 138 sweep net transects and plant communities in 124 vegetation plots in cabbage, wheat, sugar beet and barley. Higher configurational crop heterogeneity by strip cropping reduced herbivore abundances and increased natural enemy species richness in organic cabbage strips. Cabbage in MONO had a significantly higher herbivore abundance (+11%) and a lower natural enemy species richness (−57%) than cabbage in STRIP. Higher compositional crop heterogeneity by sowing additional plant species in strips (STRIPMIX) significantly increased plant abundance (+33%), plant species richness (+21%), total aerial arthropod abundance (+45%), and total aerial arthropod species richness (+21%) compared to STRIP. Our work shows that both configuration of crop areas (MONO vs. STRIP) and plant species diversity within strips (STRIP vs. STRIPMIX) can support arthropod biodiversity and natural pest suppression, but that arthropod responses dif

Pollination deficits can compromise fruit yield and quality and have been reported in several fruit crops. It is unknown whether there is a pollination deficit in the production of Korla fragrant pear, Pyrus sinkiangensis, in China, and if so, whether this deficit can be mitigated by the use of managed honeybees (Apis mellifera). We assessed insect communities, flower visitation, pollination deficit and honeybee contribution to pear pollination in Korla fragrant pear orchards in Xinjiang, China. Insect communities were monitored using colored pan traps, and pollination deficit was assessed by comparing fruit set with open pollination to that with hand pollination in orchards without beehives from 2018 to 2021. The contribution of honeybees to pollination was assessed by comparing flower visitation, fruit set and fruit quality in pear orchards with and without beehives in 2020 and 2021. In orchards without beehives, wild bees (72%) were the dominant pollinator group in pan traps, followed by honeybees (15%), moths, hoverflies, butterflies and wasps (Vespidae). Fruit set in these orchards was much lower with open pollination (8 ± 2%) than with hand pollination (74 ± 4%). When comparing pollination in orchards with and without beehives in 2020 and 2021, we found that honeybees were responsible for most of the flower visits in orchards with (96%) and without beehives (66%). Wild bees were responsible for 1% and 6% of flower visits in orchards with and without beehives, respectively. Fruit set was significantly higher in orchards with beehives (38 ± 9%) than in orchards without beehives (12 ± 3%), while fruit set and sugar content were positively associated with pollinator visitation rate. The findings reveal a large pollination deficit in Korla fragrant pear orchards, and show that this deficit can be mitigated using managed honeybees.

Pollen are an important food source for numerous insects and may be used as natural markers in ecological studies. However, to make inferences about the movement rates of insects based on their gut contents, information on pollen digestion rates is needed. Here, we assessed how the consumption and digestion rates of pollen ingested by Chrysoperla carnea Stephens (Neuroptera: Chrysopidae) adults are influenced by plant species, temperature, and sex. We offered pollen of two insect-pollinated plants – Acer pseudoplatanus L. (Sapindaceae) and Helianthus annuus L. (Asteraceae) – and two wind-pollinated plants – Fraxinus excelsior L. (Oleaceae) and Quercus rubra L. (Fagaceae) – differing in size and protein content, to adult lacewings at two temperatures, 20 and 25 °C. After feeding, lacewings were allowed to digest pollen for up to 14 days, sampled at 10 time intervals. At each of these intervals, lacewings were frozen and the internal pollen were obtained through acetolysis and quantified under a light microscope. The number of pollen grains decreased exponentially over time and declined faster for Acer than for the other three plant species. The half-life and the time at which 95% of the pollen grains were digested were lower for Acer than for the other plant species. Lacewings consumed more pollen grains from Acer and Quercus than from Fraxinus and Helianthus. Male lacewings consumed 30% fewer pollen grains than females, but without differences in their digestion rates. Our results show that lacewings consumed higher amounts of high-protein pollen (Acer and Quercus) and that digestion rates differed among plant species, which could be linked to their structural characteristics. The variable digestion rates of pollen grains may influence the study of lacewing diet composition. Studies that make inferences about the pollen diet or movement ecology of lacewings by analysing their gut contents should account for species-specific pollen digestion rates.

The challenge to reconcile agricultural production with the conservation of biodiversity and associated ecosystems services has triggered interest in the design of pest suppressive landscapes. However, the uniqueness of species-specific responses to management and landscape context hamper our ability to make generalizations for landscape design, and we often lack quantitative indicators to make inferences about the pest suppressive potential of landscape designs. Here I examine the literature to underpin design principles based on source-sink theory. The potential of landscapes to support herbivore populations is associated with the area of source habitat, source strength, and the ability of herbivores to detect host plants. The potential of natural enemies to suppress herbivore populations is associated with their potential for numerical response, time to colonization and natural enemy diversity. Insecticide applications and other intensive management practices can turn treated fields into sinks. The analysis reveals that landscape features or management practices influence multiple processes at the same time, and that well-documented landscape features associated with high pest suppression potential generally discourage herbivores and/or favour natural enemies. The evaluation of landscapes in terms of source habitats for specific herbivores and their natural enemies may reveal context-specific information that allow a better quantitative understanding of pest suppression potential of landscapes.

Seventy five percent of the world's food crops benefit from insect pollination. Hence, there has been increased interest in how global change drivers impact this critical ecosystem service. Because standardized data on crop pollination are rarely available, we are limited in our capacity to understand the variation in pollination benefits to crop yield, as well as to anticipate changes in this service, develop predictions, and inform management actions. Here, we present CropPol, a dynamic, open and global database on crop pollination. It contains measurements recorded from 202 crop studies, covering 3,394 field observations, 2,552 yield measurements (i.e. berry weight, number of fruits and kg per hectare, among others), and 47,752 insect records from 48 commercial crops distributed around the globe. CropPol comprises 32 of the 87 leading global crops and commodities that are pollinator dependent. Malus domestica is the most represented crop (32 studies), followed by Brassica napus (22 studies), Vaccinium corymbosum (13 studies), and Citrullus lanatus (12 studies). The most abundant pollinator guilds recorded are honey bees (34.22% counts), bumblebees (19.19%), flies other than Syrphidae and Bombyliidae (13.18%), other wild bees (13.13%), beetles (10.97%), Syrphidae (4.87%), and Bombyliidae (0.05%). Locations comprise 34 countries distributed among Europe (76 studies), Northern America (60), Latin America and the Caribbean (29), Asia (20), Oceania (10), and Africa (7). Sampling spans three decades and is concentrated on 2001-05 (21 studies), 2006-10 (40), 2011-15 (88), and 2016-20 (50). This is the most comprehensive open global data set on measurements of crop flower visitors, crop pollinators and pollination to date, and we encourage researchers to add more datasets to this database in the future. This data set is released for non-commercial use only. Credits should be given to this paper (i.e., proper citation), and the products generated with this database should

Cassava flour is the main source of carbohydrates for family farmers in the Amazon region of Brazil. Cassava is mainly grown under shifting cultivation, in recurrent cultivation periods initiated through slash-and-burn. Its sustainability is, however, questioned due to the associated deforestation and often rapidly decreasing crop productivity. There is an urgent need to make these cassava systems more sustainable and more profitable, but we currently lack a deep understanding of the key factors governing their productivity. We conducted an on-farm study on 37 cassava fields of smallholder farmers at three locations that spanned a range of crop-fallow frequencies, some of which were initiated through slash-and-burn while others through fire-free land clearance. First, we analysed how cassava plant density at harvest was related with pedoclimatic and management factors in slash-and-burn systems. Second, we assessed the relationship between plant density and cassava root yield at harvest and conducted a yield gap analysis to better understand which factors govern cassava productivity beyond plant density in slash-and-burn systems. Finally, we compared cassava productivity between slash-and-burn and the fire-free land clearing techniques that some farmers started to adopt in the study region. Cassava yields averaged 7.2 ± 5.4 Mg ha-1 (50% of the average yield of 14.2 Mg ha-1 in the Pará State), and ranged from 0 (in case of root rot diseases) to 24 Mg ha-1. Cassava yield was associated with plant density at harvest (ranging from 0 to 10 000 plants ha-1), suggesting that managing plant density is a key determinant of the attainable yield levels. In addition, differences in cassava root yields could be largely explained by differences in labour inputs for weeding and fallow clearing, the effect of the latter depending on soil texture. Therefore, our results suggest that labour is a key production factor for cassava in the shifting cultivation systems of the Eastern Amazo

Species cross-boundary response is a key mechanism affecting species spillover into agricultural fields. However, temporal changes in edge permeability, which may depend on the seasonal availability of resources in both matrix and native habitats, remain poorly understood. Here we tested how edge crossing behavior and the associated spillover of birds into sun coffee plantations respond to landscape structure and seasonality. We monitored the movement of six insectivorous understory bird species (four forest specialists and two forest generalists) using an automated telemetry system along a gradient of forest cover (7–60%) during two seasons (dry versus wet) at nine sampling sites at the Brazilian Atlantic forest. We monitored 116 individuals and obtained a total of 15 129 bird detections across seasons. Bird resistance to crossing edges was strongly driven by an interaction between seasonality and forest cover in the surrounding landscape, with higher resistance to crossing edges along the dry season and in landscapes with lower amount of forest cover. Furthermore, spillover patterns in plantations were driven by an interaction between forest cover and distance from forest edges, but this was most pronounced for forest-specialist bird species. Forest specialists moved more intensively and farther from edges in more forested landscapes, whereas forest generalists showed similar patterns of occupation regardless of forest cover and isolation. Our study contributes to a better understanding of avian cross-boundary responses and spillover in response to landscape structure across seasons, and the factors driving bird movement decisions in anthropogenic landscapes. There are a myriad of possible mechanisms governing movement decisions, and these mechanisms may interact in complex ways and remain important foci for research within the fields of tropical ecology and evolution.

Insecticide use and landscape context are major drivers for the abundance of beneficial arthropods, such as predators, parasitoids and pollinators. However, the relative importance of local and landscape-wide insecticide use is not well understood, and it is unclear to what extent impacts of insecticides on beneficial arthropod populations are moderated by landscape composition. We collected and analysed data on beneficial arthropod abundance and local and landscape-wide insecticide use across 38 Dutch landscapes. We used regression to study the associations between beneficial arthropod abundance (response), insecticide use and landscape factors. Insects were sampled by sweep netting and yellow sticky traps in field margins (‘sampling sites’) in the summer of 2017 and 2018. We paired organic and conventional sites in the same landscape setting. We used three indicators of insecticide use: management (organic vs. conventional), Treatment Frequency Index of insecticides applied in the field adjacent to the sampling site, and the estimated landscape-wide average quantity of insecticides applied per ha within a 1 km radius around the sampling site. Abundances of beneficial arthropods in field margins, assessed by sweep netting, were negatively associated with the estimated quantity insecticide applied in the surrounding landscape, while arthropod sampling by sticky traps did not show this relationship. Pollinator abundance was negatively associated with conventional management and with the frequency of insecticide applications in the adjacent field, while predator and parasitoid abundance did not show significant associations with local insecticide use indicators. Negative impacts of insecticide use were not moderated in more diverse landscapes with higher proportions of semi-natural habitats. Policy implications. Insecticide impacts on arthropod populations extend beyond the fields in which they are used. Awareness of the potential landscape-wide effects of pesticides

Seventy five percent of the world's food crops benefit from insect pollination. Hence, there has been increased interest in how global change drivers impact this critical ecosystem service. Because standardized data on crop pollination are rarely available, we are limited in our capacity to understand the variation in pollination benefits to crop yield, as well as to anticipate changes in this service, develop predictions, and inform management actions. Here, we present CropPol, a dynamic, open, and global database on crop pollination. It contains measurements recorded from 202 crop studies, covering 3,394 field observations, 2,552 yield measurements (i.e., berry mass, number of fruits, and fruit density [kg/ha], among others), and 47,752 insect records from 48 commercial crops distributed around the globe. CropPol comprises 32 of the 87 leading global crops and commodities that are pollinator dependent. Malus domestica is the most represented crop (32 studies), followed by Brassica napus (22 studies), Vaccinium corymbosum (13 studies), and Citrullus lanatus (12 studies). The most abundant pollinator guilds recorded are honey bees (34.22% counts), bumblebees (19.19%), flies other than Syrphidae and Bombyliidae (13.18%), other wild bees (13.13%), beetles (10.97%), Syrphidae (4.87%), and Bombyliidae (0.05%). Locations comprise 34 countries distributed among Europe (76 studies), North America (60), Latin America and the Caribbean (29), Asia (20), Oceania (10), and Africa (7). Sampling spans three decades and is concentrated on 2001–2005 (21 studies), 2006–2010 (40), 2011–2015 (88), and 2016–2020 (50). This is the most comprehensive open global data set on measurements of crop flower visitors, crop pollinators and pollination to date, and we encourage researchers to add more datasets to this database in the future. This data set is released for non-commercial use only. Credits should be given to this paper (i.e., proper citation), and the products generated with this da

Seventy five percent of the world's food crops benefit from insect pollination. Hence, there has been increased interest in how global change drivers impact this critical ecosystem service. Because standardized data on crop pollination are rarely available, we are limited in our capacity to understand the variation in pollination benefits to crop yield, as well as to anticipate changes in this service, develop predictions, and inform management actions. Here, we present CropPol, a dynamic, open and global database on crop pollination. It contains measurements recorded from 202 crop studies, covering 3,394 field observations, 2,552 yield measurements (i.e. berry weight, number of fruits and kg per hectare, among others), and 47,752 insect records from 48 commercial crops distributed around the globe. CropPol comprises 32 of the 87 leading global crops and commodities that are pollinator dependent. Malus domestica is the most represented crop (32 studies), followed by Brassica napus (22 studies), Vaccinium corymbosum (13 studies), and Citrullus lanatus (12 studies). The most abundant pollinator guilds recorded are honey bees (34.22% counts), bumblebees (19.19%), flies other than Syrphidae and Bombyliidae (13.18%), other wild bees (13.13%), beetles (10.97%), Syrphidae (4.87%), and Bombyliidae (0.05%). Locations comprise 34 countries distributed among Europe (76 studies), Northern America (60), Latin America and the Caribbean (29), Asia (20), Oceania (10), and Africa (7). Sampling spans three decades and is concentrated on 2001-05 (21 studies), 2006-10 (40), 2011-15 (88), and 2016-20 (50). This is the most comprehensive open global data set on measurements of crop flower visitors, crop pollinators and pollination to date, and we encourage researchers to add more datasets to this database in the future. This data set is released for non-commercial use only. Credits should be given to this paper (i.e., proper citation), and the products generated with this database should

The development of agroecosystems that can provide multiple ecosystem services with a reduced need of external inputs, requires management practices that foster ecological processes to enhance soil quality and crop productivity. We assessed the direct and indirect impacts of farmers' management practices on plant diversity, soil quality and crop productivity in coffee and pasture fields belonging to different types of farms: agroeco-logical, conventional, and large-scale. The study was carried out in twelve farms in the Zona da Mata, Brazil. For each of the total of 24 fields (twelve pastures and twelve coffee) we recorded 41 variables associated with management practices, indicators of plant diversity (taxonomical, structural and functional diversity) and soil quality (biological, chemical and physical properties). The direct and indirect effects of management on plant diversity, soil quality and in the case of coffee, crop productivity, were assessed using structural equation models. In the case of pastures, we found that increased plant diversity due to agroecological management resulted in higher soil quality, probably due to higher soil litter cover and plant structural heterogeneity. Yet, practices presented in the agroecological farms also had a direct negative effect on soil quality, which indicates that increased plant diversity in pastures needs to be combined with other agroecological management practices than currently adopted. In the case of coffee, we show that despite the higher weeding intensity and higher use of external inputs in large-scale and conventional coffee farming systems, these practices did not result in increased soil quality or coffee productivity as compared to agroecological systems. In contrast, agroecological coffee management was associated with increased plant diversity, which, in turn, was positively associated with soil microbial biomass carbon. Our results highlight a causal pathway of agroecological management leading to incr

Forest conservation on privately owned lands is a cornerstone of the Brazilian environmental policy framework. Brazilian legislation requires that all farms in the country maintain and protect forest areas known as Legal Reserves. Since Legal Reserves have major implications for forest conservation and agricultural production, it is key that we understand landholders' perceptions towards Legal Reserves. We applied Q methodology to identify different perspectives of medium and large landholders on Legal Reserves and their relation to agricultural intensification in the municipality of Paragominas, eastern Amazon. We conducted 31 interviews in which landholders sorted 36 statements in a quasi-normal distribution array. Three groups of landholders were identified: 1) Land use planning enthusiasts (n = 16) were interested in zoning initiatives to explore alternative landscape designs and legislation that may deliver better conservation and production outcomes; 2) Agrochemical-based agriculture supporters (n = 7) held the most critical views against Legal Reserves and perceived their costs as higher than the potential environmental and life quality benefits; 3) Policy complacent-market responders (n = 4) showed no interest in Legal Reserves reforms and were the most market driven group.. While Paragominas has achieved notable successes in halting large-scale deforestation through a social “Green Municipality” pact, addressing persisting forest degradation and fragmentation in the region remains a key priority. Local governance initiatives that account for multi-stakeholder perceptions on forest conservation can foster dialogue and mutual understanding to effectively conserve and restore Legal Reserves. Insights on large landholders' perceptions on Legal Reserves can inform such governance processes to reconcile forest conservation and sustainable agricultural intensification in Paragominas.

Traditional farming landscapes in China consist of small irregular fields with an intimately interspersed semi-natural habitat network of field margins, but are increasingly converted into consolidated ones that consist of standardized fields with reduced areas of field margins and other semi-natural habitat. It is unclear how such farmland consolidation influences pollinator communities, and if there is a negative effect, whether this effect is mitigated by semi-natural habitat present in the wider landscape. We compared the diversity and abundance of wild pollinators in oilseed rape fields that were embedded in landscapes that consisted either of traditional or consolidated farmland. The landscapes spanned a range of semi-natural habitat area from 10% to 73% at a scale of one km radius in Jiangxi Province, China. Pollinators were sampled using pan traps during two years (2015 and 2019). Results showed that pollinator diversity was positively associated with the proportion of semi-natural habitat in both traditional and consolidated farming landscapes, but was higher in traditional farming landscapes. In both years, there was no difference in pollinator abundance between landscapes with traditional and consolidated fields. The results indicate that the network of field margins in traditional farmland supports a diverse pollinator community, and that land consolidation has equivalent effects on pollinator diversity as substantial decreases in semi-natural habitat in the wider landscape. The role of semi-natural habitat in supporting farmland biodiversity and its associated services needs therefore to be considered in plans for farmland consolidation.

Forest conservation on privately owned lands is a cornerstone of the Brazilian environmental policy framework. Brazilian legislation requires that all farms in the country maintain and protect forest areas known as Legal Reserves. Since Legal Reserves have major implications for forest conservation and agricultural production, it is key that we understand landholders' perceptions towards Legal Reserves. We applied Q methodology to identify different perspectives of medium and large landholders on Legal Reserves and their relation to agricultural intensification in the municipality of Paragominas, eastern Amazon. We conducted 31 interviews in which landholders sorted 36 statements in a quasi-normal distribution array. Three groups of landholders were identified: 1) Land use planning enthusiasts (n = 16) were interested in zoning initiatives to explore alternative landscape designs and legislation that may deliver better conservation and production outcomes; 2) Agrochemical-based agriculture supporters (n = 7) held the most critical views against Legal Reserves and perceived their costs as higher than the potential environmental and life quality benefits; 3) Policy complacent-market responders (n = 4) showed no interest in Legal Reserves reforms and were the most market driven group. While Paragominas has achieved notable successes in halting large-scale deforestation through a social “Green Municipality” pact, addressing persisting forest degradation and fragmentation in the region remains a key priority. Local governance initiatives that account for multi-stakeholder perceptions on forest conservation can foster dialogue and mutual understanding to effectively conserve and restore Legal Reserves. Insights on large landholders' perceptions on Legal Reserves can inform such governance processes to reconcile forest conservation and sustainable agricultural intensification in Paragominas.

Sustainable food production requires approaches that reconcile agricultural production with the conservation and sustainable use of natural resources, biodiversity and associated ecosystem services. While the contribution of agriculture to the provision of individual ecosystem services has received considerable scientific attention, little is known about the extent to which tropical landscapes can meet societal expectations related to food production and environmental sustainability simultaneously. We assessed how the spatial configuration of pedo-morphology and land uses influences the provision of three soil-based ecosystem services in eastern Amazonia: carbon storage (CS), habitat for biodiversity (HB), and agricultural commodity production (CP). We use the Functional Land Management framework to assess the supply and demand of these ecosystem services in a spatially explicit manner to identify areas of (mis)matches and trade-offs in the municipality of Paragominas, Brazil. The supply of ecosystem services was informed by a literature review for the various combinations of pedo-morphological characteristics and land uses in the region. The demand for ecosystem services was mapped based on federal and state policy targets. Mapping the supply and demand of CS indicated that half of the carbon in the region is stored in remnants of undisturbed forest which cover only a third of the municipality. Demand for HB in terms of forested area is met but it does not guarantee safeguarding biodiversity. Roughly a third of the territory shows scarce quality of HB even when compliant with legislation. Concerning CP, we identified areas where both supply and the demand to increase production are relative high due to road access and lower intensification costs. The demand for agricultural production can eventually incentivize the expansion of agriculture on fertile soils, which could compromise environmental targets. Our results suggest that the simultaneous delivery of multiple

Overreliance on synthetic insecticides in global agriculture is the outcome of a “pesticide treadmill,” in which insecticide-induced pest resistance development and the depletion of beneficial insect populations aggravate farmers' pesticide dependencies. Examples of the pesticide treadmill have been witnessed repeatedly over the past seven decades, prompting the question whether the rapid uptake and usage patterns of neonicotinoid insecticides and their associated environmental impact are in accordance with this recurrent phenomenon. We hypothesize a conceptual framework in which treadmills are enforced by enabling or disabling drivers within four domains: pest management decisions at the farm level, characteristics of farming landscapes, science and technology, and societal demands. These drivers then tend to create a self-enforcing pesticide “lock-in.” We then analyze several post-1950s historical case studies with reference to this framework, e.g., those involving sprays of the highly hazardous DDT and methyl-parathion, in which the pesticide treadmill was initiated, sustained, and broken, and compare this with current patterns in neonicotinoid use. Historical case studies further illustrate how treadmills occur in three phases in which (i) a limited number of insecticides are routinely used, (ii) resistance development of pests results in the increased crop injury, prompting increased frequency of applications with a wider range of products, (iii) breaking out of the pesticide “lock-in” by policy change and adoption of alternative technologies that lowered chemical inputs and improved agro-ecosystem functioning. The analysis shows similarities as well as differences between neonicotinoid usage patterns and historic pesticide treadmills, and provides guidance on how to effectively avoid or dismantle pesticide treadmills in global agriculture.

Species-specific responses to the environment can moderate the strength of interactions between plants, herbivores and parasitoids. However, the ways in which characteristics of plants, such as genotypic variation in herbivore induced volatiles (HIPVs) that attract parasitoids, affect trophic interactions in different contexts of plant patch size and plant neighbourhood is not well understood. We conducted a factorial field experiment with white cabbage (Brassica oleracea) accessions that differ in the attractiveness of their HIPVs for parasitoids, in the context of different patch sizes and presence or absence of surrounding Brassica nigra plants. Parasitism rates of experimentally introduced Pieris brassicae caterpillars and the presence of naturally occurring Pieris spp. caterpillars in the plots were assessed throughout the growing season. The abundance of Pieris caterpillars was neither affected by cabbage accession nor plot size. Later in the season, when B. nigra plants had senesced, fewer caterpillars were found on cabbage plants in plots with a B. nigra border. Parasitism rates fluctuated over the season, and were not affected by plot size. However, the B. nigra border negatively affected parasitism rates on the accession that is less attractive to the parasitoid Cotesia glomerata, but not on the more attractive accession. Our results show that plant variation in HIPVs can differentially influence herbivores and parasitoids depending on characteristics of the surrounding vegetation context. These findings underscore the importance of considering the interaction between focal plant traits and neighbourhood context to reliably predict trophic cascades., Species-specific responses to the environment can moderate the strength of interactions between plants, herbivores and parasitoids. However, the ways in which characteristics of plants, such as genotypic variation in herbivore induced volatiles (HIPVs) that attract parasitoids, affect trophic interactions in different contexts of plant patch size and plant neighbourhood is not well understood. We conducted a factorial field experiment with white cabbage (Brassica oleracea) accessions that differ in the attractiveness of their HIPVs for parasitoids, in the context of different patch sizes and presence or absence of surrounding Brassica nigra plants. Parasitism rates of experimentally introduced Pieris brassicae caterpillars and the presence of naturally occurring Pieris spp. caterpillars in the plots were assessed throughout the growing season. The abundance of Pieris caterpillars was neither affected by cabbage accession nor plot size. Later in the season, when B. nigra plants had senesced, fewer caterpillars were found on cabbage plants in plots with a B. nigra border. Parasitism rates fluctuated over the season, and were not affected by plot size. However, the B. nigra border negatively affected parasitism rates on the accession that is less attractive to the parasitoid Cotesia glomerata, but not on the more attractive accession. Our results show that plant variation in HIPVs can differentially influence herbivores and parasitoids depending on characteristics of the surrounding vegetation context. These findings underscore the importance of considering the interaction between focal plant traits and neighbourhood context to reliably predict trophic cascades.

Context: Land use and land cover (LULC) changes may affect the provision of ecosystem services. However, little is known how LULC changes influence the spatio-temporal variation in ecosystem service and their interactions along altitudinal gradients. Objectives: Here we assessed the spatio-temporal variation of eight ecosystem services in an altitudinal gradient between the year of 1986 and 2015, and quantified the effect of LULC transitions on the provision and interactions of ecosystems services. Methods: We modelled and mapped eight ecosystem services in an altitudinal gradient characterized by low (< 600 m), middle (600–1200) and high altitudes (> 1200) in Zona da Mata, Minas Gerais state, Brazil. We quantified changes in ecosystem services by contrasting ecosystem service maps between 1986 and 2015, and explored how four common LULC transitions affected the variation and the interactions between the eight ecosystem services. Results: The spatio-temporal analysis indicated that six out of eight ecosystem services increased from 1986 to 2015, while soil erosion control and water flow regulation decreased. In areas above 1200 m, regulating services dominated, while in areas below 1200 m provisioning service were most evidenced. LULC transitions from forest to agricultural areas, and vice versa, resulted in trade-offs between provisioning and regulating ecosystem services. Conclusions: LULC changes drive the spatio-temporal variation of ecosystem services along an altitudinal gradient with contrasting biophysical conditions. Future management of ecosystem services in the landscapes should take into the account the biophysical conditions and the consequences of specific LULC transitions.

While the biocontrol potential of natural enemies is well established, it is largely unknown how landscape‐mediated effects on pest and natural enemy communities impact the cascade of biocontrol potential, crop injury, yield and profit, taking into account crop management and surrounding landscape composition.We compared natural biocontrol with chemical control according to local farmers’ practice, across the ‘full cascade’ from natural enemy and pest abundance to crop injury, yield loss, yield and economic performance. This two‐year study was conducted in 20 rice fields embedded in a gradient of landscapes from crop‐dominated to semi‐natural habitat‐dominated, in subtropical China, the world's largest rice producing region.Natural enemies suppressed brown planthopper population growth in unsprayed plots, irrespective of landscape composition. However, crop injury was lower in pesticide treated plots than in unsprayed plots, and yields in sprayed plots were 20% higher than in unsprayed plots. Nevertheless, pesticide applications were only profitable in less than half of the cases when only costs for pesticides were considered, and in less than one third of the cases when costs for pesticides and labour were considered.Synthesis and applications. Our findings question the cost‐effectiveness of current chemical‐based pest management in farming, and highlight opportunities for more ecologically based pest management strategies based on the widespread activity of natural enemies. Pest damage and biocontrol, however, are largely independent from the landscape context, which might be due to the small‐scale character of Chinese rice landscapes. To maintain high levels of biocontrol, conserving this small‐scale character appears more important than increasing the proportion of semi‐natural habitat

Secondary forest succession can be an effective and low-cost strategy to increase forest cover and the associated biodiversity and soil functions. However, little is known about how soil functions develop during succession, and how vegetation attributes influence soil functions, especially in highly biodiverse and fragmented landscapes in the tropics. Here we assessed a wide range of indicators of taxonomic (e.g. number of tree species), structural (e.g. basal area, canopy openness) and functional diversity (e.g. community weighted means of functional traits) of tree species, as well as indicators for soil functions related to soil organic matter accumulation, nutrient cycling and soil cover in secondary forest patches ranging from 5 to 80 years. Two recently abandoned agricultural fields were included as the starting point of forest succession and two primary forest patches served as references for the end point of forest succession. Four ecological hypotheses, centred around the role of functional diversity, structural diversity and biomass, were tested to explore mechanisms in which forest vegetation may influence soil functions. Most measures of structural, taxonomic and functional diversity converged to values found in primary forests after 25–50 years of succession, whereas functional composition changed from acquisitive to conservative species. Soil carbon and nutrient cycling showed a quick recovery to the levels of primary forests after 15 years of succession. Although soil cover also increased during succession, levels of primary forests were not reached within 80 years. Variation in tree height and trait dominance were identified as aboveground drivers of carbon and nutrient cycling, while aboveground biomass was the main driver of litter accumulation, and the associated soil cover and water retention. Our results indicate that secondary forest succession can lead to a relative fast recovery of nutrient and carbon cycling functions, but not of soil cover.

Sustainable food production requires approaches that reconcile agricultural production with the conservation and sustainable use of natural resources, biodiversity and associated ecosystem services. While the contribution of agriculture to the provision of individual ecosystem services has received considerable scientific attention, little is known about the extent to which tropical landscapes can meet societal expectations related to food production and environmental sustainability simultaneously. We assessed how the spatial configuration of pedo-morphology and land uses influences the provision of three soil-based ecosystem services in eastern Amazonia: carbon storage (CS), habitat for biodiversity (HB), and agricultural commodity production (CP). We use the Functional Land Management framework to assess the supply and demand of these ecosystem services in a spatially explicit manner to identify areas of (mis)matches and trade-offs in the municipality of Paragominas, Brazil. The supply of ecosystem services was informed by a literature review for the various combinations of pedo-morphological characteristics and land uses in the region. The demand for ecosystem services was mapped based on federal and state policy targets. Mapping the supply and demand of CS indicated that half of the carbon in the region is stored in remnants of undisturbed forest which cover only a third of the municipality. Demand for HB in terms of forested area is met but it does not guarantee safeguarding biodiversity. Roughly a third of the territory shows scarce quality of HB even when compliant with legislation. Concerning CP, we identified areas where both supply and the demand to increase production are relative high due to road access and lower intensification costs. The demand for agricultural production can eventually incentivize the expansion of agriculture on fertile soils, which could compromise environmental targets. Our results suggest that the simultaneous delivery of multiple

Context: Tritrophic interactions may be affected by local factors and the broader landscape context. At small spatial scales, carnivorous enemies of herbivorous insects use herbivore-induced plant volatiles (HIPVs) to find herbivores, but it is unknown whether variation in plant attractiveness due to differential HIPV emission can enhance recruitment of carnivores from the wider landscape. Objectives: We studied whether parasitism of caterpillars of the butterfly Pieris brassicae on white cabbage was influenced by landscape composition and cover with brassicaceous species that provide hosts for parasitoids of P. brassicae in 19 landscapes in the Netherlands. We also investigated whether differential attraction of parasitoids to herbivore-infested plants affected parasitism of P. brassicae caterpillars by using different accessions as proxies for HIPV emission. Results: The cabbage accession that is highly attractive to parasitic wasps recruited more wasps than a less attractive accession, but only when parasitism rates were high. Parasitism rate as proxy of wasp recruitment correlated positively with the cover of brassicaceous plants and area of arable land, suggesting that these habitats support hosts for the wasps and their population growth. In contrast, forest area was negatively associated with parasitism rates. Conclusions: Our study shows that the degree of attractiveness of plants to parasitoids, which is probably mediated by HIPVs, can be a useful predictor of parasitism, but needs to be considered within the landscape context. To understand the strength of tritrophic interactions it is crucial to consider local-scale processes driven by plant-trait variation in combination with landscape-scale processes that determine carnivore abundance.

Biological pest control depends on the ability of natural enemies to find herbivore-infested plants, which is often guided by herbivore-induced plant volatiles (HIPVs). While foraging behavior of natural enemies has been extensively studied under controlled conditions, little is known on how odor-guided foraging behavior is influenced by fluctuating weather conditions in the field. Here we investigated how HIPV-guided foraging of Cotesia glomerata parasitoids is influenced by prevailing weather conditions in the field. C. glomerata females were released in 5 m radius circles of cabbage plants infested with Pieris brassicae caterpillars, and host finding success and direction of foraging activity was assessed by recapturing parasitoids on the host-infested plants. Wind speed and direction, humidity, barometric pressure and temperature was recorded and related to parasitoid foraging activity. Parasitoid foraging behavior was studied in more detail by observing individually released parasitoids in 0.5 m circles with host-infested cabbages. Recapture rates and movement direction of parasitoids was influenced by an interaction between humidity, wind speed, temperature and change in barometric pressure. High humidity and low wind speed was generally positively associated with host finding success. Direct observations of parasitoid flight behavior confirmed the influence of humidity and wind speed. Successful host finding in upwind direction was only observed at wind speeds below 3 m/s. Our study highlights the complex ways in which weather variables moderate parasitoid foraging behavior under field conditions. Since unfavorable weather conditions result in a strong reduction in parasitoid foraging efficiency, weather conditions are an important factor in the effectiveness of parasitoids as biocontrol agents.

Species-specific responses to the environment can moderate the strength of interactions between plants, herbivores and parasitoids. However, the ways in which characteristics of plants, such as genotypic variation in herbivore induced volatiles (HIPVs) that attract parasitoids, affect trophic interactions in different contexts of plant patch size and plant neighbourhood is not well understood. We conducted a factorial field experiment with white cabbage Brassica oleracea accessions that differ in the attractiveness of their HIPVs for parasitoids, in the context of different patch sizes and presence or absence of surrounding Brassica nigra plants. Parasitism rates of experimentally introduced Pieris brassicae caterpillars and the presence of naturally occurring Pieris spp. caterpillars in the plots were assessed throughout the growing season. The abundance of Pieris caterpillars was neither affected by cabbage accession nor plot size. Later in the season, when B. nigra plants had senesced, fewer caterpillars were found on cabbage plants in plots with a B. nigra border. Parasitism rates fluctuated over the season, and were not affected by plot size. However, the B. nigra border negatively affected parasitism rates on the accession that is less attractive to the parasitoid Cotesia glomerata, but not on the more attractive accession. Our results show that plant variation in HIPVs can differentially influence herbivores and parasitoids depending on characteristics of the surrounding vegetation context. These findings underscore the importance of considering the interaction between focal plant traits and neighbourhood context to reliably predict trophic cascades.

While pest management tends to focus on pests that are already present in crops, non-crop hosts may play a crucial role in supporting pest populations outside the crop growing season. Non-crop hosts may allow pest populations to persist throughout the year, build-up and colonise crops after emergence. Here, we assess the hosts of the Rutherglen bug, Nysius vinitor Bergroth, which is a polyphagous native insect pest of growing economic importance in Australia. We conducted a literature review on the occurrence of N. vinitor on crop and non-crop hosts and analysed field survey data on N. vinitor abundance from two independent field studies in three agricultural regions of Australia. We differentiated between juvenile (nymph) and adult stages to consider the function of plants as reproduction sites. The literature review resulted in reports of N. vinitor on 44 crop species from 18 plant families. Pigweed Portulaca oleracea and capeweed Arctotheca calendula were the most cited weed hosts. In the field study, N. vinitor was primarily found on exotic weeds and grasses within pastures, Lucerne and degraded native vegetation remnants. While N. vinitor was found on a total of 16 weed plant families, juvenile stages of N. vinitor were most often observed on fleabane (Conyza spp.), goosefoot Chenopodium pumilio (Amaranthaceae) and plants of the Asteraceae family, indicating that these are important host plants for N. vinitor reproduction. Grasses appear to be an important but understudied host plant group; citations in the literature do not reflect the extent to which N. vinitor was found on grasses in the field. In contrast, the field survey indicated that very few native plant species supported N. vinitor, which was consistent across regions and confirms findings from the literature review. Our findings suggest that exotic weeds and grasses (but not native plants) play a key role in supporting N. vinitor populations in Australian agricultural landscapes. Reducing ex

Ethiopia is now the second most populated country in Africa with more than 100 million people and an annual population growth rate of 3%. Here, we assess how the on-going expansion of arable land and urban areas is affecting the availability of common resources, such as forest and grazing land, and the availability of biomass for food, feed, and energy. Taking the Hawassa area in the Rift Valley of Ethiopia as a study case, this study aims at analysing the drivers of change of farming systems, assessing farmers' responses to these drivers and appreciating the consequences for the agricultural landscapes' composition. We found that (i) national-level policies, climate and soil fertility changes, population increase, and urban expansion were major drivers of farming systems change in the Hawassa area, (ii) forests and grasslands have been progressively replaced by cropland and urban areas, and (iii) these changes resulted in fragmentation and diversification of local agricultural landscapes with potential consequences for ecosystem service provision. Farmers responded with the following three main livelihood strategies: consolidation, diversification and specialization. These changes led to more diverse and fragmented agricultural landscapes. This research contributes to the ongoing debate about the viability of small farms.

Lepidopteran stemborers are a serious pest of maize in Africa. While farmers have adopted cultural control practices at the field scale, it is not clear how these practices affect stemborer infestation levels and how their efficacy is influenced by landscape context. The aim of this 3-year study was to assess the effect of field and landscape factors on maize stemborer infestation levels and maize productivity. Maize infestation levels, yield and biomass production were assessed in 33 farmer fields managed according to local practices. When considering field level factors only, plant density was positively related to stemborer infestation level. During high infestation events, length of tunnelling was positively associated with planting date and negatively with the botanical diversity of hedges. However, the proportion of maize crop in the surrounding landscape was strongly and positively associated with length of tunnelling at 100, 500, 1000 and 1500 m radius, and overrode field level management factors when considered together. Maize grain yield was positively associated with plant density and soil phosphorus content, and not negatively associated with the length of tunnelling. Our findings highlight the need to consider a landscape approach for stemborer pest management, but also indicate that maize is tolerant to low and medium infestation levels of stemborers.

Chemical information influences the behaviour of many animals, thus affecting species interactions. Many animals forage for resources that are heterogeneously distributed in space and time, and have evolved foraging behaviour that utilizes information related to these resources. Herbivore-induced plant volatiles (HIPVs), emitted by plants upon herbivore attack, provide information on herbivory to various animal species, including parasitoids. Little is known about the spatial scale at which plants attract parasitoids via HIPVs under field conditions and how intraspecific variation in HIPV emission affects this spatial scale. Here, we investigated the spatial scale of parasitoid attraction to two cabbage accessions that differ in relative preference of the parasitoid Cotesia glomerata when plants were damaged by Pieris brassicae caterpillars. Parasitoids were released in a field experiment with plants at distances of up to 60 m from the release site using intervals between plants of 10 or 20 m to assess parasitism rates over time and distance. Additionally, we observed host-location behaviour of parasitoids in detail in a semi-field tent experiment with plant spacing up to 8 m. Plant accession strongly affected successful host location in field set-ups with 10 or 20 m intervals between plants. In the semi-field set-up, plant finding success by parasitoids decreased with increasing plant spacing, differed between plant accessions, and was higher for host-infested plants than for uninfested plants. We demonstrate that parasitoids can be attracted to herbivore-infested plants over large distances (10 m or 20 m) in the field, and that stronger plant attractiveness via HIPVs increases this distance (up to at least 20 m). Our study indicates that variation in plant traits can affect attraction distance, movement patterns of parasitoids, and ultimately spatial patterns of plant–insect interactions. It is therefore important to consider plant-trait variation in HIPVs when st

Human land use threatens global biodiversity and compromises multiple ecosystem functions critical to food production. Whether crop yield-related ecosystem services can be maintained by a few dominant species or rely on high richness remains unclear. Using a global database from 89 studies (with 1475 locations), we partition the relative importance of species richness, abundance, and dominance for pollination; biological pest control; and final yields in the context of ongoing land-use change. Pollinator and enemy richness directly supported ecosystem services in addition to and independent of abundance and dominance. Up to 50% of the negative effects of landscape simplification on ecosystem services was due to richness losses of service-providing organisms, with negative consequences for crop yields. Maintaining the biodiversity of ecosystem service providers is therefore vital to sustain the flow of key agroecosystem benefits to society.

Deforestation rates in Brazil have undergone an unprecedented decline of more than 70% since 2005. Changes in policies, institutions and social movements provided a platform for this radical slowdown. Moreover, in 2012 a revised version of the Brazilian Forest Code determined that all rural properties in the Amazons should maintain between 50-80% of their area as native forest, known as Legal Reserves (LR), and 100% of the riparian forest. To achieve these targets, deforested properties should subscribe to an Environmental Regularization Plan (PRA). Nevertheless, recent research indicates that biodiversity and carbon storage are still decreasing in areas of eastern Amazonia due to forest fragmentation and degradation. The current government policies and mechanisms are not efficient at incentivizing PRA compliance, nor at connecting forest patches to create a structural network of connected habitats and optimize carbon storage. The Paragominas municipality is one of the oldest frontier towns in this region heading towards agricultural intensification and environmental conservation. We explore land use change scenarios in this area to decrease forest fragmentation while taking into account local economic demands. First, we applied the Functional Land Management framework to assess the spatial variability of three ecosystem services (ES): commodity production, carbon storage and habitat for biodiversity. This assessment was linked to a farm typology based on a survey of 40 farms, to farmers' perceptions on LR and ES using the Q methodology, and to jurisdictional agricultural and environmental policies. Land use changes were modelled in ArcGIS by simulating forest restoration in deforested areas with poor soils, and agricultural intensification on soils suitable for agriculture currently covered by degraded forest. Using FRAGSTAT 3.3 for spatial pattern analysis, we explored landscape scenarios where forest fragmentation decreases as compared to the current status. The

1. Agriculture benefits from ecosystem services provided by mobile agents, such as biological pest control by natural enemies and pollination by bees. However, methods that can generate spatially explicit predictions and maps of these ecosystem services based on empirical data are still scarce. 2. Here we propose a generic statistical model to derive kernel functions to characterize the spatial distribution of ecosystem services provided by mobile agents. The model is similar in spirit to a generalized linear model, and uses data of landscape composition and ecosystem services assessed at target sites to estimate parameters of the kernel. The approach is tested in a simulation study and illustrated by an empirical case study on parasitism rates of the diamondback moth Plutella xylostella. 3. The simulation study shows that the scale parameter of the exponential power kernel can be estimated with limited bias, whereas estimation of the shape parameter is difficult. For the case study the model provides biologically relevant estimates for the kernel associated with parasitism of Plutella xylostella. These estimates can be used to generate ecosystem service maps for existing or planned landscapes. The case study reveals that predictions can be sensitive to the parameter values for the width and shape of the kernel, and to the link function used in the statistical model. 4. In the last two decades numerous empirical studies assessed ecosystem services at target sites and related these to the surrounding landscape. Our method can take advantage of these data by estimating underlying kernels that can be used to map the spatial distribution of ecosystem services. However, empirical data that can discriminate between alternative kernel shapes remain critical.

Agroecology is increasingly promoted by scientists, non-governmental organisations (NGO's), international organisations and peasant movements as an approach to foster the transition to sustainable and equitable food systems. The challenges to agroecological transitions are not the same for all farmers, as they can face different social and bio-physical conditions. We developed a farm typology combining participatory and quantitative methodologies to assess and categorise farm diversity and its implications for developing strategies to promote agroecological transitions. The participatory typology was developed during workshops to acquire insights on local farmers' perceptions and knowledge, and to generate hypotheses on family farm diversity. The participatory-based hypotheses were tested in the quantitative farm characterisation, which provided information on household characteristics, production strategies, land use, participation in public policies and extension services. Farms were located in Zona da Mata, Minas Gerais, Brazil, which harbour a wide diversity of farmers and where different actors have been engaged in agroecological transitions for the past 30 years. Our main findings were: (i) In the face of agroecological transitions, farmers differ in their management strategies, practices and principles; (ii) farmers identified as agroecological typically had stronger engagements in a network composed of farmers' organisations, universities and NGO's; (iii) agroecological farms showed great potential to provide a wide range of ecosystem services as they featured a higher crop diversity and a higher number of crops for self-consumption; (iv) to promote agroecology, it is crucial to recognise peasant knowledge, to change the dominant discourse on agriculture through social movement dynamics, and to generate support from public policies and funds; and (v) participatory and quantitative methodologies can be combined for more precise and relevant assessments of agr

Background: Insect pollinators play an important role in crop pollination, but the relative contribution of wild pollinators and honey bees to pollination is currently under debate. There is virtually no information available on the strength of pollination services and the identity of pollination service providers from Asian smallholder farming systems, where fields are small, and variation among fields is high. We established 18 winter oilseed rape (Brassica napus L.) fields along a large geographical gradient in Jiangxi province in China. In each field, oilseed rape plants were grown in closed cages that excluded pollinators and open cages that allowed pollinator access. The pollinator community was sampled by pan traps for the entire oilseed rape blooming period. Results: Oilseed rape plants from which insect pollinators were excluded had on average 38% lower seed set, 17% lower fruit set and 12% lower yield per plant, but the seeds were 17% heavier, and the caged plants had 28% more flowers and 18% higher aboveground vegetative biomass than plants with pollinator access. Oilseed rape plants thus compensate for pollination deficit by producing heavier seeds and more flowers. Regression analysis indicated that local abundance and diversity of wild pollinators were positively associated with seed set and yield/straw ratio, while honey bee abundance was not related to yield parameters. Conclusions: Wild pollinator abundance and diversity contribute to oilseed rape yield by enhancing plant resource allocation to seeds rather than to above-ground biomass. This study highlights the importance of the conservation of wild pollinators to support oilseed rape production in small-holder farming systems in China.

Immobilized preys are routinely used in agro-ecological exposure studies to quantify predation of pests under field conditions, but this method has not been validated. Our purpose was to determine the validity of using immobilized adults of the major rice pest Nilaparvata lugens, brown plant hopper (BPH), as sentinels. We used direct observation by video recording to determine the causal agents of removal of field exposed BPH sentinels with two experiments: 1) we recorded removal events of dead, immobilized BPH; and 2) we compared removal of (i) dead, immobilized BPH, (ii) live, immobilized BPH, and (iii) live, mobile BPH. Long-horned grasshoppers were responsible for most removals of dead, immobilized BPH, in both experiments. Predatory ground beetles removed most of the live, immobilized BPH, whereas frogs were the major predators of live, mobile BPH. Overall, we showed that removal of immobilized sentinel prey is not representative for predation of live, mobile prey, stressing the need for a critical assessment of commonly used sentinel methods. In addition, we found that frogs played the major role in predation of BPH in rice. As current strategies to enhance biocontrol of planthoppers in rice focus on arthropod natural enemies, this finding could have major implications.

Rice fields host a large diversity of arthropods, but investigating their population dynamics and interactions is challenging. Here we describe the modification and application of a leaf blower-vac for suction sampling of arthropod populations in rice. When used in combination with an enclosure, application of this sampling device provides absolute estimates of the populations of arthropods as numbers per standardized sampling area. The sampling efficiency depends critically on the sampling duration. In a mature rice crop, a two-minute sampling in an enclosure of 0.13 m2 yields more than 90% of the arthropod population. The device also allows sampling of arthropods dwelling on the water surface or the soil in rice paddies, but it is not suitable for sampling fast flying insects, such as predatory Odonata or larger hymenopterous parasitoids. The modified blower-vac is simple to construct, and cheaper and easier to handle than traditional suction sampling devices, such as D-vac. The low cost makes the modified blower-vac also accessible to researchers in developing countries.