Semi-natural Habitats Research Articles

Smarter in the city? Lizards from urban and semi-natural habitats do not differ in a cognitive task in two syntopic species.

Urbanization occurs at a global scale, imposing dramatic and abrupt environmental changes that lead to biodiversity loss. Yet, some animal species can handle these changes, and thrive in such artificial environments. One possible explanation is that urban individuals are equipped with better cognitive abilities, but most studies have focused on birds and mammals and yielded varied results. Reptiles have received much less attention, despite some lizard species being common city dwellers. The Italian wall lizard, Podarcis siculus, and the common wall lizard, Podarcis muralis, are two successful lizards in anthropogenic habitats that thrive in urban locations. To test for differences in a cognitive skill between urban and semi-natural environments, we investigated inhibitory control through a detour task in syntopic populations of the two species, across 249 lizards that were tested in partially artificial field settings. Sophisticated inhibitory control is considered essential for higher degrees of cognitive flexibility and other higher-level cognitive abilities. In this task, we confronted lizards with a transparent barrier, separating them from a desired shelter area that they could only reach by controlling their impulse to go straight and instead detour the barrier. We found no differences between lizards in urban and semi-natural environments, nor between species, but females overall performed better than males. Moreover, 48% of the lizards in our study did not perform a correct trial in any of the 5 trials, hinting at the difficulty of the task for these species. This study is among the first to address lizard cognition, through their inhibitory control, as a potential explanation for success in cities and highlights one should be careful with assuming that urban animals generally have enhanced cognitive performance, as it might be taxa, task, or condition dependent.

The drivers of plant turnover change across spatial scales in the Azores

Beta diversity patterns are essential for understanding how biological communities are structured. Geographical and environmental factors, as well as species dispersal ability, are important drivers of beta diversity, but their relative importance may vary across spatial scales. In this study, we evaluate whether beta diversity changes across geographical scales and analyse how different drivers affect turnover patterns of native seed plants in an oceanic archipelago, the Azores (Portugal). Using a 500 × 500 m resolution grid, we selected cells that are covered by one of the following habitats: native forest, naturalized vegetation and seminatural pastures. We calculated species turnover at three spatial scales: 1) between islands, 2) between cells within each island, and finally 3) between cells of each of the habitats of interest in each island. We then calculated the contribution of dispersal syndromes (endozoochory, epizoochory, hydrochory and anemochory) to turnover at each of the scales. Lastly, we assessed the relationship between geographical and climatic distances and habitat type with turnover. Turnover was higher at the smallest spatial scale, particularly in seminatural pastures, and decreased with increasing spatial scales, a pattern potentially associated with the historical fragmentation and current patchy distribution of native forest and seminatural habitats in the Azores. Dispersal syndromes and habitat type had a negligible effect on turnover at all scales. Geographical distance had a positive effect on turnover at all scales, increasing its importance with scale. The relationship between turnover and climatic distance was only significant at the intermediate and small scales in specific islands and habitats. Therefore, scale plays an important role at determining the effect of the drivers of turnover, in particular geographical and climatic distance. These results highlight the need to carefully select the scale of analysis when studying turnover patterns, as well as identifying the potential drivers associated with each spatial scale.

Bees and their interactions with flowering plants in disturbed and semi-natural settings

A knowledge of bee populations is scarce, particularly in sub-Saharan Africa, where human-induced changes appear to have a considerable negative effect on wild bees. The goal of the study was to assess the abundance, diversity, and richness of bees and their interactions (or visitation) with flowering plants in disturbed and semi-natural habitats in Tanzania. Bees were sampled using sweep nets and pan traps whereas bee-plant interaction and floral abundance were visually assessed. We show that semi-natural habitats are crucial places for bees to forage and nest, as their richness, diversity, and species composition were higher than disturbed habitats. The study areas in semi-natural habitats also had a higher number of bee visits compared to the disturbed habitats. The lower number of bees found in disturbed habitats implies that human-caused alterations have a negative impact on foraging resources and bee communities. Furthermore, we recorded more than 400 bee-plant interactions and high floral abundance in semi-natural habitats compared to disturbed habitats. However, in both disturbed and semi-natural habitats, there was a positive relationship between floral abundance and bee abundance. This reveals that floral resources have a significant impact on bee abundance and their visitation. Our findings demonstrate further that, if natural environments are disturbed and floral resources are depleted, bee populations may decline. Therefore, habitat management, whether disturbed or semi-natural, is critical for the survival of bees.

Crop and landscape heterogeneity increase biodiversity in agricultural landscapes: A global review and meta-analysis.

Agricultural intensification not only increases food production but also drives widespread biodiversity decline. Increasing landscape heterogeneity has been suggested to increase biodiversity across habitats, while increasing crop heterogeneity may support biodiversity within agroecosystems. These spatial heterogeneity effects can be partitioned into compositional (land-cover type diversity) and configurational heterogeneity (land-cover type arrangement), measured either for the crop mosaic or across the landscape for both crops and semi-natural habitats. However, studies have reported mixed responses of biodiversity to increases in these heterogeneity components across taxa and contexts. Our meta-analysis covering 6397 fields across 122 studies conducted in Asia, Europe, North and South America reveals consistently positive effects of crop and landscape heterogeneity, as well as compositional and configurational heterogeneity for plant, invertebrate, vertebrate, pollinator and predator biodiversity. Vertebrates and plants benefit more from landscape heterogeneity, while invertebrates derive similar benefits from both crop and landscape heterogeneity. Pollinators benefit more from configurational heterogeneity, but predators favour compositional heterogeneity. These positive effects are consistent for invertebrates and vertebrates in both tropical/subtropical and temperate agroecosystems, and in annual and perennial cropping systems, and at small to large spatial scales. Our results suggest that promoting increased landscape heterogeneity by diversifying crops and semi-natural habitats, as suggested in the current UN Decade on Ecosystem Restoration, is key for restoring biodiversity in agricultural landscapes.

Direct and indirect effects of linear non-cultivated habitats on epigaeic macroarthropod assemblages

Non-cultivated habitats are indispensable ecological spaces within agricultural landscapes that support biodiversity and associated ecosystem services on farmland, thereby contributing to sustainable agriculture. The abundance of taxonomic groups within these habitats serves as a reliable indicator of the diversity levels in epigaeic macroarthropod communities, while the functional groups offer insights into the trophic dynamics of macroarthropods. In recent decades, the impact of non-cultivated habitats on biodiversity within agricultural contexts has received increasing attention. However, few studies have focused on the pathways and factors that influence epigaeic macroarthropod assemblages in different non-cultivated habitats. In this study, Changtu County, a typical agricultural county in the Northeastern Black Soil Region of China, was selected as the study area. The functional and taxonomic groups of epigaeic macroarthropod abundance in different non-cultivated habitats were compared. The structural equation model (SEM) was used to evaluate the direct and indirect effects of non-cultivated habitat type, soil nutrients and vegetation structure reflecting major differences in non-cultivated habitat types on epigaeic macroarthropod assemblages. Our results showed that: (1) linear semi-natural non-cultivated habitats around fields can effectively enhance landscape connectivity. Among these habitats, woodlands (WL), grasslands (GL), and ditches (CD) with high herbaceous vegetation density are usually more favorable for biodiversity conservation in agricultural ecosystems. (2) While dirt roads (DR) and paved roads (PR) may affect the mobility and foraging ability of epigaeic macroarthropods, improving herbaceous vegetation structures along road margins (e.g., planting flowering plants, establishing vegetation buffer zones) can effectively enhance field biodiversity. (3) The characteristics of herbaceous vegetation community are the most important factors affecting the functional and taxonomic groups of epigaeic macroarthropods in different non-cultivated habitats, especially the herbaceous vegetation height (PAH) and species abundance (PAB). In addition, for epigaeic macroarthropods taxonomic groups, non-cultivated habitats affect them not only directly through herbaceous vegetation, but also indirectly through soil organic carbon (SOC). Our results emphasize that in the planning of agricultural landscapes, it is feasible to achieve a harmonious synergy between ecosystem stability and agricultural production through strategic allocation and alteration of herbaceous vegetation structure and soil conditions in different types of non-cultivated habitats.

Expansion of apple cultivation increases the abundance of codling moth (Cydia pomonella) in agricultural landscapes of China.

Agricultural land-use change is an important driver of pest population dynamics, and can alter source-sink dynamics and the concentration-dilution effects of the landscape. Understanding the effects of land use on pests at both landscape and regional levels is essential for the development of sustainable pest management strategies given the large changes occurring in cropping systems in China. At the landscape level, we investigated the impacts of landscape composition and edge density on pheromone trap catch of codling moth (Cydia pomonella) in apple orchards, in Aksu, Xinjiang, China. At the regional scale, we conducted a meta-analysis using data from studies performed across the Aksu area in recent decades, to assess the relationship between trends in codling moth abundance and the area of apple cultivation. Both extensive planting of apple and large areas of annual crops in the landscape increased the abundance of codling moth, whereas the presence of secondary host plants (peach, pear, walnut, plum, and apricot) had a negative effect. Seminatural habitats and landscape edge density did not significantly affect codling moth abundance. The responses of different generations of codling moth to landscape factors were varied. At the regional level, codling moth occurrence was positively correlated with the expansion of apple production areas. Expansion of apple cultivation increases the abundance of codling moth in agricultural landscapes. We recommend decreasing the area devoted to monocultures of apple when designing agricultural landscapes and increasing plantings of secondary host crops to dilute and reduce the abundance of codling moth. © 2024 Society of Chemical Industry.

Buckwheat (Fagopyrum esculentum) floral strips support natural enemies and maintain yields in organic green bean (Phaseolus vulgaris) crops

Arthropod natural enemies can contribute to pest management by consuming crop pests, but populations of these natural enemies may be low within crops due to a lack of resources. Floral strips can provide these resources and support natural enemy communities, which in turn can suppress pest populations and thereby improve crop yields. Buckwheat (Fagopyrum esculentum Moench) floral strips were added to experimental plots of organic green beans (Phaseolus vulgaris L.) and paired with control plots, without floral strips, to determine their impact on arthropod communities, crop yields, and pest control costs. Crop yields were maintained, but costs of pest control significantly lower (16%) in plots with floral strips. This was not explained by an increased abundance or diversity of natural enemies or a decrease of pests (i.e. all herbivores). Instead, the composition of arthropod natural enemy communities were similar between buckwheat floral strips and the crop, suggesting that the floral strips support natural enemies already present within crops. Semi-natural edge habitat in control plots, had a unique community of natural enemies, which had little spillover into the crop and therefore may have little impact on biological control. These results suggest that higher crop yields can be achieved with reduced inputs, such as insecticides, by adding floral strips to crops as they may support the natural enemies present within crops. Future studies should consider the impacts of specific natural enemies, rather than diversity, and direct measurements of biological control to connect the impact of floral strips to crop yields.

Spatial planning constraints will mitigate the fragmentation trajectory of natural and semi-natural landscapes: a case of Lushan City, China

ContextThe biodiversity faces an underlying threat from landscape fragmentation resulting from rapid urbanization. Examining the future trajectory of landscape fragmentation is imperative to understanding the impact of current spatial planning constraints on natural and semi-natural habitat preservation, ecosystem services, and sustainability.MethodsWe employed a Patch-generating Land Use Simulation (PLUS) model to simulate and predict the land use and landscape pattern changes in Lushan City under two distinct scenarios: “Planning Constraints (PC)” and “Natural Development (ND)”. We then identified an appropriate landscape fragmentation index (LFI) that effectively captured the fragmentation essence. To determine the optimal scale, we adopted an experimental approach using both the moving window (MW) method and the semi-variance function. By constructing a LFI spatiotemporal sequence and conducting trend analysis, we identified the potential fragmentation areas (PFA) with significant fragmentation tendencies.ResultsThe spatial planning constraints will (1) prevent the encroachment of construction land into 2.14 km2 of cropland, 0.21 km2 of forest, and 0.13 km2 of grassland; (2) shift the highly fragmented area from the northeastern portion of Lushan to the planned area defined by the development boundary; (3) mitigate and decelerate the trend of landscape fragmentation in natural and semi-natural landscapes, decrease PFA by 7.74 km2 and preserve 15.61 km2 of natural landscapes. (4) still leave 29.42% of forest and 22.82% of grassland at risk of fragmentation.ConclusionsSpatial planning constraints will effectively control the potential fragmentation in natural and semi-natural landscapes by changing the spatial distribution of LFI and PFA. This control mechanism will greatly exclude the anthropogenic impact and ensure the conservation of habitats. The habitats remaining within PFA should be focused in future eco-management optimization.

How seasonality, semi-natural habitat cover and compositional landscape heterogeneity affect pollen collection and development of Apis mellifera colonies in Mediterranean agro-sylvo-pastoral systems

ContextThe reduction in the abundance and diversity of flowering plant species, mainly due to landscape alteration and consequent habitat loss, negatively affects honey bee populations and is the main driver of their decline. To safeguard pollination service and food security, we need to know how landscape characteristics affect the availability of pollen sources and consequently colony performance across seasons.ObjectivesWe therefore here explore how seasonality, percentage of semi-natural habitat cover and compositional landscape heterogeneity affect the abundance, richness, diversity and composition of pollen collected by honey bees and the development of their colonies in a Mediterranean area where agro-sylvo-pastoral systems are widely spread.MethodsFor the purpose of our study, pollen samples were collected over a year from colonies of Apis mellifera placed in four sampling sites selected across a gradient of landscape heterogeneity and where semi-natural habitats were predominant at various levels within an agro-sylvo-pastoral zone. Simultaneously, the extension of the sealed brood of the same colonies was periodically evaluated.ResultsWe found that the amount of pollen collected by honey bees was positively correlated with the percentage of semi-natural habitat cover and that increasing habitat diversity at the landscape level had a significant positive effect on the richness and diversity of pollen collected by honey bees. In addition, season significantly affected the amount, diversity and composition of pollen collected by honey bees. Furthermore, bee colony growth was positively correlated with richness, diversity and amount of pollen collected by honey bees.ConclusionOur study highlights the importance of an abundant and diverse pollen diet for honey bee colony development, which in agro-sylvo-pastoral systems seems to be ensured by a heterogeneous landscape dominated by different types of semi-natural habitats.

Anthropogenic climate and land-use change drive short- and long-term biodiversity shifts across taxa

Climate change and habitat loss present serious threats to nature. Yet, due to a lack of historical land-use data, the potential for land-use change and baseline land-use conditions to interact with a changing climate to affect biodiversity remains largely unknown. Here, we use historical land use, climate data and species observation data to investigate the patterns and causes of biodiversity change in Great Britain. We show that anthropogenic climate change and land conversion have broadly led to increased richness, biotic homogenization and warmer-adapted communities of British birds, butterflies and plants over the long term (50+ years) and short term (20 years). Biodiversity change was found to be largely determined by baseline environmental conditions of land use and climate, especially over shorter timescales, suggesting that biodiversity change in recent periods could reflect an inertia derived from past environmental changes. Climate–land-use interactions were mostly related to long-term change in species richness and beta diversity across taxa. Semi-natural grasslands (in a broad sense, including meadows, pastures, lowland and upland heathlands and open wetlands) were associated with lower rates of biodiversity change, while their contribution to national-level biodiversity doubled over the long term. Our findings highlight the need to protect and restore natural and semi-natural habitats, alongside a fuller consideration of individual species’ requirements beyond simple measures of species richness in biodiversity management and policy.

STARdbi: A pipeline and database for insect monitoring based on automated image analysis

Insects are highly abundant and diverse, and play major roles in ecosystem functions. Monitoring of insect populations is key to their sustainable management. However, the labor and expertise needed to identify insects, and the challenges of archiving the wealth of data collected in monitoring programs, often limit these efforts. We describe a pipeline to reduce the barriers associated with curating and mining big data of insect biodiversity. The pipeline, STARdbi, includes capturing flying insects with sticky traps, scanning the traps, storing the trap-images in a public database with a web-based interface, and applying machine learning models to extract information from the images. To illustrate the insights that can be gained from STARdbi, we describe two case studies. One of them involves monitoring of circadian activity patterns of grain pests and of their natural enemies, and the other compares insect abundance, biomass and size distributions between agricultural and semi-natural habitats. We invite the community of insect ecologists to contribute to the STARdbi database, and to use its image analysis tools to address diverse ecological and evolutionary questions.

Agricultural landscape composition alters ant communities in maize fields more than plant diversity enrichment

Abstract. Pasaribu DN, Rizali A, Tarno H, Priawandiputra W, Johannis M, Buchori D. 2024. Agricultural landscape composition alters ant communities in maize fields more than plant diversity enrichment. Biodiversitas 25: 205-213. Fragmented natural habitats in human-modified landscapes play a crucial role in conserving biodiversity. Ants, as keystone species, are integral to terrestrial ecosystems, making it essential to comprehend the factors influencing their survival. This study investigates the impact of agricultural landscape composition and plant diversity enrichment (flowering plants) management on shaping ant communities in maize (Zea mays L.) fields. The research occurred in maize fields surrounded by other crops, semi-natural habitats, and housing areas in Malang District, East Java, Indonesia. The four agricultural areas were divided into control and treatment plots, considering landscape composition parameters, particularly Class Area (CA) and the Number of Patches (NP), measured within a 500 m radius. The landscape around the maize fields was characterized by manually digitizing land use. Six types of plant diversity enrichment were employed in this study: wild cosmos (Cosmos caudatus), white buttercup (Turnera subulata), sunflower (Helianthus annuus), long bean (Vigna unguiculata), ornamental bean (Arachis pintoi), and coral vine (Antigonon leptopus). The study was divided into the dry season (April-July 2022) and the wet season (September-December 2022). Ant sampling was conducted using pitfall traps and, based on generalized linear models, revealed that plant diversity enrichment management did not affect species richness, abundance, or composition of ants. Landscape composition positively influenced ant species richness but negatively impacted species composition, particularly the number of semi-natural habitat patches. Maize crop age also positively influenced ant species richness but negatively affected beta diversity. Wet season was also found to have a negative effect on beta diversity. In conclusion, the proportion of semi-natural habitats in agricultural landscapes and crop age contribute significantly to species richness and species composition of ants.

Temporal dynamics in the composition of bird communities along a gradient of farmland restoration.

Revegetation plantings are a key activity in farmland restoration and are commonly assumed to support biotic communities that, with time, replicate those of reference habitats. Restoration outcomes, however, can be highly variable and difficult to predict; hence there is value in quantifying restoration success to improve future efforts. We test the expectation that, over time, revegetation will restore bird communities to match those in reference habitats; and assess whether specific planting attributes enhance restoration success. We surveyed birds in 255 sites in south-east Australia, arranged along a restoration gradient encompassing three habitat types: unrestored farmland (paddocks), revegetation plantings (comprising a chronosequence up to 52 years old) and reference habitats (remnant native vegetation). Surveys were undertaken in 2006/2007 and again in 2019, with data used to compare bird assemblages between habitat types. We also determined whether, in the intervening 12 years, bird communities in revegetation had shifted toward reference habitats on the restoration gradient. Our results showed that each habitat contained a unique bird community and that, over time, assemblages in revegetation diverged away from those in unrestored farmland and converged toward those in reference habitats. Two planting attributes influenced this transition: the bird assemblages of revegetation were more likely to have diverged away from those of unrestored farmland (with scattered mature trees) 12 years later if they were located in areas with more surrounding tree cover, and were mostly ungrazed by livestock (compared with grazed plantings). Our results highlight three key ways in which revegetation contributes to farmland restoration: (1) by supporting richer and more diverse bird assemblages than unrestored farmland, (2) by enhancing beta diversity in rural landscapes through the addition of a unique bird community, and (3) by shifting bird assemblages toward those found in reference habitats over time. However, revegetation plantings did not replicate reference habitats by ~40-50 years in our region, and complete convergence may take centuries. These findings have implications for environmental offset programs and mean that effective conservation in farmland environments depends on the retention and protection of natural and seminatural habitats as a parallel management strategy to complement restoration.

Effect of land-use intensity and adjacent semi-natural habitats on wild and honey bees of meadows

Most terrestrial ecosystems are shaped by the pollination service provided by insects, foremost bees. As bees are also important pollinators of crop plants, they are key for both the pollination of wild plants and for agricultural production. Meadows and semi-natural habitats (SNHs) are important habitats for bees. However, there is limited knowledge on how land-use intensity of meadows affects wild bees and managed Western honey bees. Further, it is unknown whether SNHs adjacent to meadows affect bees in meadows. Here, we examined in a landscape dominated by grasslands, the effects of land-use intensity (nitrogen input, grazing intensity, mowing frequency), flower availability and adjacent SNHs on bee communities in meadows. We recorded more than 5000 individuals of 87 species of bees and found no effect of land-use intensity on wild and honey bees. Flowering plant species richness had a positive effect on bee species richness in one study year. Though we recorded more bee species in SNHs than meadows, overall and specifically in ecologically specialized bee species (e.g. parasitic bees, oligoleges), the availability of adjacent SNHs did not affect bee abundance and richness in meadows. We discuss why land-use intensity and SNHs adjacent to meadows did not affect bees in meadows and conclude that SNHs are important in sustaining functionally diverse bee communities in landscapes dominated by grasslands.

Habitat diversification associated with urban development has a little effect on genetic structure in the annual native plant Commelina communis in an East Asian megacity.

Urban development greatly alters the natural and semi-natural habitats of native plants. Urbanisation results in a range of diverse habitats including remnant agricultural lands, urban parks, and roadside habitats. This habitat diversity often promotes trait divergence within urban areas. However, the mechanisms by which diverse urban habitats influence the population genetic structure of individual plant species remain poorly understood. We investigated the effects of urbanisation on genetic diversity and structure within 24 Commelina communis populations across diverse habitat types (rural agricultural land, urban agricultural land, urban park land, and urban roadsides) within the Kyoto-Osaka-Kobe megacity in Japan. We conducted multiplexed inter-simple sequence repeat genotyping to compare genetic diversity among populations in different habitats. We also examined the correlation between Nei's genetic distance and geographic and environmental distances and performed principal coordinate analysis (PCoA) to evaluate genetic differentiation among urban habitats. There were no significant differences in genetic diversity indices between urban and rural populations and among urban habitat types. Although we detected no isolation-by-distance structure in population pairs of the same habitat type and in those of different habitats, the difference in surrounding landscape facilitated genetic differentiation not only between urban and rural habitats but also between different urban habitats. PCoA revealed no clear genetic differentiation among rural and urban habitat populations. Our findings indicate that the establishment of diverse habitat types through urbanisation has no and little impact on genetic diversity and structure, respectively, in C. communis, likely due to its high selfing rate and ability to adapt to urban conditions.

New grasslands promote pollination but not biological pest control in nearby arable fields in the short term

Agricultural intensification is a major threat to farmland biodiversity and associated ecosystem services. Semi-natural habitats are integral to the preservation of farmland biodiversity and ecosystem services, however, the extent in which they contribute to specific services is largely unclear. We studied predation rates of ground-dwelling predatory arthropods, and pollination success within old permanent grasslands, newly established grasslands and arable fields near and far from new grasslands. We evaluated whether grassland restoration can enhance pollination and biological control in crop fields. For this purpose, we established new grassland strips within cereal fields, which directly bordered existing permanent grasslands. We evaluated if the distance to these old and new grasslands affects the delivery of the two ecosystem services within crop fields. We found significantly higher seed numbers and seed weight in sentinel plants placed in old grasslands, new grasslands and nearby arable fields compared to distant arable fields. We also found significantly decreasing seed numbers and seed weight in sentinel plants placed in distant arable fields with increasing distance from old grasslands, while pollination success was not affected by distance in nearby arable fields. Contrary, we did not find any significant effects of new grasslands on biological control. Our study showed that 3 years after establishing grasslands arable fields benefited from the proximity of flower-rich new grasslands through increased pollination success though not regarding biological control. This indicates that, on a short term, establishing new grasslands can support beneficial arthropods in providing ecosystem services such as pollination. Predators, in contrast, might take longer to establish effective populations that denote higher predation rates. Our study provides a baseline for future long-term studies to better evaluate pollination and pest control patterns within arable fields.

Apple pest and pathogen reduction in landscapes with large patch size and small area of orchards: a national-scale analysis

ContextThe composition and configuration of habitats in agricultural landscapes may determine crop damage resulting from pests or pathogens either by directly affecting their population dynamics or through indirect effects on their natural enemies.ObjectivesThe aim of this study was to assess the impact of landscape composition and configuration on the occurrence and damage caused by the codling moth and apple scab in apple orchards.MethodsUsing monitoring data at the French national scale, we examined how the proportion of landscape area grown with orchards, the mean patch area of orchards, the share of organic orchards and the proportion of woodlands and grasslands affected the occurrence and damage of these two pests from 2015 to 2019 in approximately sixty apple orchards each year.ResultsLandscapes with a higher proportion of orchards supported a higher occurrence of apple scab and earlier colonisation of codling moths. In addition, we found that codling moth damage decreased with increasing orchard patch area in the landscape. The proportion of seminatural habitats or organic farming in the landscape never significantly explained pest occurrence or damage.ConclusionsOur results clearly highlight the importance of considering the amount and spatial arrangement of the pests’ and pathogens’ host crops to understand their infestation levels. Our study calls for the territorial management of orchard distribution to limit pesticide use in apple orchards.

Butterfly loss in urban landscapes and nature reserves

ContextUrbanization and landscape homogenization are main drivers causing biodiversity loss across the globe. The transformation of natural and semi-natural habitats into agro-environments and settlement areas causes the reduction of species diversity, and thus faunal homogenization. ObjectiveIn this study, we analyse changes in land-cover and habitat configuration and test for changes in species richness and community composition of butterflies in an urban area and a nature reserve. MethodWe analysed historical and recent aerial and satellite pictures, and studied the butterfly fauna for two areas in northern Austria, the urban area around Salzburg city and the nature reserve Bluntautal in close geographic proximity. For these analyses we consider the period 1946–2018. ResultsThe proportion of settlement area and forest increased in average by about 5%. Size of field copses increased and small-scale connectivity and thus landscape complexity decreased in both areas. In the same time span, we found a decrease in butterfly species richness for both areas, and in the nature reserve Bluntautal particularly for the past two decades by 50%. The species community composition changed significantly, with severe losses of specialist and xerothermophilic species which rely on open and extensively used ecosystems. ConclusionsThe findings underpin that the reduction of landscape complexity and the intensification of land-use including urbanization drives the loss of diversity of butterflies and changes in species composition, today dominated by some few generalist species. This trend is particularly observable for the nature reserve Bluntautal, where a large proportion of species diversity has disappeared in recent years despite nature conservation. This case underlines habitat management in nature reserves is needed to hold a high level of habitat quality and to preserve the entire species diversity.

Effects of agricultural landscape heterogeneity on pollinator visitation rates in Mediterranean oilseed rape

Agricultural intensification, by changing land use and modifying the yearly configuration and composition through crop sequences, affects the abundance and diversity of pollinators and, consequently, pollination. This study aims to assess the impact of the characteristics of agricultural landscapes on pollinator abundance in the Mediterranean region. We studied the response of three major wild pollinator groups (hoverflies, bumblebees, and wild bees) to four landscape characteristics: three related to composition, namely, equivalent crop diversity in the sampling year (eRg), previous year equivalent crop diversity (eRgP) and percentage of seminatural habitats (SNH), and one related to landscape configuration, namely, mean field size (MFS). For this evaluation, we selected twenty-two oilseed rape fields (OSRs) differing in surrounding landscape characteristics within a 1-km radius. Multimodel inference indicates that landscape variables affect pollinator groups differently. The percentage of SNH was the most important variable having a positive influence on the abundance of bumblebees, while eRgP and MFS were found to be important for the abundance of wild bees and hoverflies. These data allow us to prioritize actions aimed at specific groups of pollinators, improve agricultural landscape schemes, promote the conservation of wild pollinators, promote crop diversity at the landscape scale and increase the extent of seminatural areas.

Influence of larval growth and habitat shading on retreatment frequencies of biolarvicides against malaria vectors

Effective larviciding for malaria control requires detailed studies of larvicide efficacies, aquatic habitat characteristics, and life history traits of target vectors. Mosquitoes with brief larval phases present narrower timeframes for biolarvicidal effects than mosquitoes with extended periods. We evaluated two biolarvicides, VectoBac (Bacillus thuringiensis israelensis (Bti)) and VectoMax (Bti and Bacillus sphaericus) against Anopheles funestus and Anopheles arabiensis in shaded and unshaded habitats; and explored how larval development might influence retreatment intervals. These tests were done in semi-natural habitats using field-collected larvae, with untreated habitats as controls. Additionally, larval development was assessed in semi-natural and natural habitats in rural Tanzania, by sampling daily and recording larval developmental stages. Both biolarvicides reduced larval densities of both species by >98% within 72 h. Efficacy lasted one week in sun-exposed habitats but remained >50% for two weeks in shaded habitats. An. funestus spent up to two weeks before pupating (13.2(10.4–16.0) days in semi-natural; 10.0(6.6–13.5) in natural habitats), while An. arabiensis required slightly over one week (8.2 (5.8–10.6) days in semi-natural; 8.3 (5.0–11.6) in natural habitats). The findings suggest that weekly larviciding, which is essential for An.arabiensis might be more effective for An. funestus whose prolonged aquatic growth allows for repeated exposures. Additionally, the longer residual effect of biolarvicides in shaded habitats indicates they may require less frequent treatments compared to sun-exposed areas.