Non-crop Habitats Research Articles

Active management of wildflower strips in commercial sweet cherry orchards enhances natural enemies and pest regulation services

To protect sweet cherry (Prunus avium L.) against pests in commercial orchards, pesticides are frequently used, but some have adverse environmental impacts. Natural enemies can deliver protection against pests but compared to the surrounding non-crop habitat their abundance is usually low in intensively managed agricultural systems. Wildflower interventions established for Conservation Biological Control as part of Integrated Pest Management (IPM) can reinstate habitat for natural enemies within cropped areas and enhance natural pest control. Over a three-year period, this more sustainable approach to crop protection was investigated in eight sweet cherry orchards protected under polytunnels in the West Midlands (UK). Wildflower strips were established in alleyways between rows of cherry trees and managed under two cutting regimes, Standard Wildflower Strips (SWS) (a single cut in late September) and Actively Managed Wildflower Strips (AMWS) (regularly cut to a height of 20 cm throughout the growing season). These were compared to unsown Control Strips (CS) (original vegetation dominated by grass species). To investigate natural enemy populations and pest regulation services, direct search, Vortis suction sampling, beat sampling, and aphid bait cards were used. Araneae (40.0% of records) and parasitoid wasps (22.7%) were the most frequent natural enemies recorded in alleyways, whilst Anystidae (51.8%) and Araneae (20.8%) were most abundant on cherry trees. Wildflower treatments almost doubled the abundance of natural enemies in alleyways, and increased abundance in cherry trees by ~15% compared to the CS. Wildflower strips increased predation of aphids (bait cards) in cherry trees by 25%. No difference in natural enemy abundance, richness or pest control was recorded between the two wildflower management regimes. Differences in natural enemy abundance and predation rates were detected despite the continued use of pesticides by growers (an average of 5.4 (± 0.4) applications per orchard per year). This study demonstrates that creating wildflower habitat in commercial sweet cherry orchards under polytunnels can boost natural enemies and the associated pest regulation services. Relative to CS, the novel grower-friendly approach of maintaining wildflower strips at a height of 20 cm with regular cutting increased flower resource availability and pest regulation services, demonstrating the potential for growers to adopt this approach as part of a robust IPM strategy.

Biodiversity in agricultural landscapes: Grassy field margins and semi-natural fragments both foster spider diversity and body size

Agricultural intensification is one of the most important drivers of biodiversity loss. To preserve taxonomic diversity in agricultural landscapes, there is an increasing need for refuge areas within agroecosystems, but best practices for providing such sites are debated. Here, we compared the taxonomic diversity and trait composition of spiders, being important terrestrial predators, among cereal fields, grassy field margins, set aside fields sown with wildflowers, and semi-natural sites within an agricultural landscape in western Germany. Spider taxonomic diversity was similarly high in all non-crop habitats, indicating a surprisingly high value of field margins and set-aside fields. Cereal fields, in contrast, were dominated by a few, mainly euryecious species. Moreover, community mean body size was smallest on cereal fields but highest on semi-natural sites, suggesting that spider body size may serve as a valuable indicator of the level of anthropogenic disturbance. Spider communities differed partly among non-crop habitats, stressing the need for combining different conservation measures to maximize taxonomic biodiversity and trait composition. These should also include remnants of natural vegetation, which were especially important for large and red list species and therefore for reaching the aims of nature conservation.

Influence of wetland borders on prevalence of fall armyworm and wasps in maize-soybean cropping system in Eastern Uganda

The non-crop habitats within agro-ecosystems are important resources for ecological and biological insect pest management. Diversified cropping systems are known to influence pest populations, however, how neighboring habitats affect pest population dynamics is not clear. This study focused on understanding the influence of wetland borders on Fall Armyworm (FAW) and wasps prevalence in a maize-soybean intercrop system in Eastern Uganda. FAW and wasps population estimates were carried out in twelve farmers’ fields stratified within 0–300 and 500–1100 meters from the wetland borderline. Data were collected biweekly from emergence until post flower growth of the crops. Results showed the prevalence of FAW was significantly higher on maize-soybean fields 500–1100 meters compared to those within 0 to 300 m from the wetland borders. While the prevalence of wasps was significantly higher in the crops at 82–219 meters from wetland borderline. It is concluded that wetland borders play a crucial role in negatively affecting crop pest populations while positively influencing natural enemy populations and these effects are influenced by distance of crop fields from the wetland border.

Habitat heterogeneity helps to mitigate pollinator nectar sugar deficit and discontinuity in an agricultural landscape

The scarcity of floral resources and their seasonal discontinuity are considered as major factors for pollinator decline in intensified agricultural landscapes worldwide. The consequences are detrimental for the stability of the environment and ecosystems. Here, we quantified the production of nectar sugars in plant species occurring in man-made, non-cropped areas (non-forest woody vegetation, road verges, railway embankments, field margins, fallow areas) of an agricultural landscape in SE Poland. We also assessed changes in the availability of sugar resources both in space (habitat and landscape scales) and in time (throughout the flowering season), and checked to what extent the sugar demands of honeybees and bumblebees are met at the landscape scale.At landscape-level, 37.6% of the available sugar resources are produced in man-made, non-cropped habitats, while 32.6% and 15.0% of sugars derive from winter rape crops and forest vegetation, respectively. Nectar sugar supplies vary greatly between man-made, non-cropped habitat types/sub-types. These areas are characterized by a high richness of nectar-producing species. However, a predominant role in total sugar resources is ascribable to a few species.Strong fluctuations in nectar resources are recorded throughout the flowering season. March and June are periods with food shortages. Abundant nectar sugars are generally found in April–May, mainly due to the mass flowering of nectar-yielding species in the forests, meadows/pastures and orchards/rapeseed crops. Heterogeneity of man-made, non-cropped habitats is essential to support the supply of July–October nectar sugars for honeybees and bumblebees. Reduced flowering in man-made non-cropped habitats can generate serious food deficiencies, as from summer towards the end of the flowering season >90% of sugars are provided by the flora of these areas. Therefore, highly nectar-yielding plant species that flower during periods of expected food shortages should be a priority for conservation and restoration programs.

Streams and rural abandonment are related to the summer activity of the invasive pest Drosophila suzukii in protected European forests

Protected native-forested areas may be occupied by fruit pests, and so, studies exploring the biotic and abiotic determinants of fruit-pest abundance in forested areas may reduce damages in crops and wild forest frugivores. The Spotted Wing Drosophila (SWD) Drosophila suzukii is an economically important fruit pest in many temperate regions around the world. During the dry summer in northwestern Spain, we assessed 24 native riparian and 32 non-riparian chestnut forest patches as non-crop habitats for the SWD. We surveyed chestnut forests in 2017 and found a positive association between spatial proximity of forest patches to streams and SWD captures, which led us to study in 2019 the stream-SWD associations in greater detail. We explored whether native-insect communities and changes in vegetation structure related to rural abandonment were associated with variation in SWD captures, while accounting for the effects of covariates, including stream distance. There were no significant associations in the riparian and non-riparian-habitat surveys between the captures of SWDs and those of native insects, including 22 families of flies and 10 families of parasitic wasps. However, captures of SWDs and of other drosophilid flies were positively related to each other and the direction of the association was reversed by stream distance, which suggests the potential role of streams in regulating interactions among non-riparian insects, including SWD. We also found correlative evidence that degraded riparian forests and the abandonment of traditional forest practices in chestnut forests may be contributing to the spread of SWD. Given the numbers of SWDs in our forest samples were similar to values in August in crop areas, it is advisable that future studies address the impacts of SWD invasion on native forest frugivores, which have been overlooked in studies of this widely distributed invasive species.

Effects of Landscape Composition on Wheat Stem Sawfly (Hymenoptera: Cephidae) and Its Associated Braconid Parasitoids.

Several agroecological and integrated pest management strategies focus on landscape management to increase complexity and foster biodiversity. However, landscape complexity does not always enhance biological control and in some cases may lead to increased pest populations. We examined the prevalence of two Bracon parasitoids, Bracon cephi Gahan and Bracon lissogaster Muesebeck (Hymenoptera: Braconidae), and their host the wheat stem sawfly Cephus cinctus Norton, a major pest of wheat. We assessed the degree of noncrop and crop host plant use and responses to landscape composition. We found no instances of parasitism by either Bracon species in our three-year, statewide winter wheat survey but found small populations of Bracon in noncrop landscapes throughout eastern and western Colorado. We used model selection to examine how local (500 m scale) and landscape (5 km scale) cover of suitable noncrop and crop habitats potentially affects abundances of Bracon and wheat stem sawfly. Our best fit model for wheat stem sawfly suggests that a decrease in noncrop cover at the landscape scale leads to an increase in wheat stem sawfly infestation. Our best fit model for Bracon parasitism suggests an increase in wheat cover at the local level results in the greatest increase in the odds of parasitism by either species of Bracon. Herbaceous cover at local and landscape scales were also significant predictors of Bracon parasitism. The results of this study suggest that pest and natural enemies respond differently to landscape composition and these responses should be evaluated before management decisions are made.

Carabid beetles (Coleoptera: Carabidae) and biological control of agricultural pests in Latin America

AbstractThe well-diversified Latin American agriculture plays an essential role in the economy of that region, through the export of food and agricultural commodities. The region is expected to continue playing a significant role in world agricultural production and trade. Carabid beetles are efficient consumers of arthropod pests and weed seeds on agricultural land, which makes them a target for studies by entomologists aiming to determine whether predatory carabids are capable of suppressing pest populations. However, carabids have been mostly studied in temperate regions of the Northern Hemisphere. Here, evidence for carabids as biocontrol agents of agricultural pests in Latin America is examined, aiming to improve understanding of this predator group in Latin American agroecosystems. The records found were organized into the following subject areas: conservation tactics, biocontrol agents, agricultural practices, and population survey. The literature review identified several gaps in knowledge of these topics, which made it possible to indicate potential research projects related to noncrop habitats, population studies, and consumption of weed seeds. Laboratory investigations of carabids’ predatory capacity indicated that they have the potential to control pests. However, field studies have failed to demonstrate that carabids significantly decreased pest densities. Although polyculture is a traditional practice of smallholder farmers in Latin America, the literature involving carabids and this sustainable agriculture practice is sparse. Looking forward, the utilization of polyculture and the existing no-till system in large fields provide opportunities for future research on ground beetles in Latin America.

Habitat niches suggest that non-crop habitat types differ in quality as source habitats for Central European agrobiont spiders

Non-crop habitats in agricultural landscapes may differ in their potential to serve as source habitats for natural enemies. To determine this potential for different habitat types, it is crucial to understand habitat preferences and the habitat niche width of natural enemies. In addition, populations of natural enemies are affected by management practices depending on their preferences for habitat strata. Here we analysed agrobiont spider preferences (very common species in arable fields) for different microhabitats (ground, herbaceous, and shrub strata) and non-crop habitats (agroecosystems, forests, scrub, meadows, steppe, and wetlands). We compared guild-specific preferences of cursorial and web-building spiders that inhabit pome fruit orchards and cereal fields using two databases on Central European spider preferences. The majority of agrobiont spiders showed a moderate niche width. Agrobiont spiders from orchards preferred the shrub stratum while spiders from cereal fields preferred the ground and herbaceous strata across habitats. Agrobiont spiders primarily utilized non-crop habitats that were structurally similar to a particular agroecosystem: spiders from orchards utilized mostly woody vegetation while spiders from cereal fields utilized mostly meadows. Moreover, cursorial and web-building spider species from cereal fields differed in their preferences for different non-crop habitats. The results highlight that non-crop habitats have different potential as sources of agrobiont spiders. The composition of non-crop habitats in agricultural landscapes may affect the functional composition and pest control potential of spider communities. Further studies focusing on the effects that landscapes have on natural enemies in local agroecosystem need to account for the identity of non-crop habitats.

Does the “Enemies Hypothesis” operate by enhancing natural enemy evenness?

Root (1973) observed fewer pests in weedy Brassica oleracea plantings, and suggested this could be because greater plant diversity bolstered resources for natural enemies and strengthened herbivore suppression (i.e., the Enemies Hypothesis) and/or disrupted host-location by specialist herbivores (i.e., the Resource Concentration Hypothesis). These proposed mechanisms have been exceptionally influential in efforts to manage agroecosystems to promote conservation biological control, yet their relative importance remains unclear. Because direct (plant-driven) and indirect (enemy-mediated) drivers of herbivore pressure are difficult to isolate experimentally, we compiled a multi-year observational dataset tracking arthropod pest and predator densities in B. oleracea plantings on over 50 farms varying in weed cover within fields as well as in habitat diversity in surrounding landscapes. We then used structural equation models to evaluate direct and indirect interaction links consistent with the Enemies and Resource Concentration Hypotheses, while also considering landscape context and enemy community structure. We predicted that non-crop habitat would limit herbivores indirectly by supporting evenly distributed communities of natural enemies. Our results revealed that weedy vegetation indeed benefitted predator evenness and thus indirectly correlated with enhanced predator densities, but instead of limiting herbivores, natural enemies seemed to track both aphids and caterpillars. Landscape diversity had no effect on predator evenness, yet appeared to benefit predator density, while having contrasting direct effects on aphids (positive) and caterpillars (negative). We found no evidence for direct negative links between weed cover and herbivores that would indicate an important role for the Resource Concentration Hypothesis. Instead, we found indirect links between weedy plants and natural enemy evenness across our network of field sites, suggesting partial support for the Enemies Hypothesis. More generally, we suggest that greater consideration of predator-predator interactions and local biodiversity effects could help explain inconsistent relationships between landscape diversity and herbivore suppression.

Insect pollination is important in a smallholder bean farming system

BackgroundMany crops are dependent on pollination by insects. Habitat management in agricultural landscapes can support pollinator services and even augment crop production. Common bean (Phaseolus vulgaris L.) is an important legume for the livelihoods of smallholder farmers in many low-income countries, particularly so in East Africa. While this crop is autogamous, it is frequently visited by pollinating insects that could improve yields. However, the value of pollination services to common beans (Kariasii) yield is not known.MethodsWe carried out pollinator-exclusion experiments to determine the contribution of insect pollinators to bean yields. We also carried out a fluorescent-dye experiment to evaluate the role of field margins as refuge for flower-visitors.ResultsSignificantly higher yields, based on pods per plant and seeds per pod, were recorded from open-pollinated and hand-pollinated flowers compared to plants from which pollinators had been excluded indicating that flower visitors contribute significantly to bean yields. Similarly, open and hand-pollinated plants recorded the highest mean seed weight. Extrapolation of yield data to field scale indicated a potential increase per hectare from 681 kg in self-pollinated beans to 1,478 kg in open-pollinated beans indicating that flower visitors contributed significantly to crop yield of beans. Our marking study indicated that flower-visiting insects including bees, flies and lepidopterans moved from the field margin flowers into the bean crop. Overall, these results show that insect pollinators are important for optimising bean yields and an important food security consideration on smallholder farms. Field margin vegetation also provides habitat for flower-visiting insects that pollinate beans. Hence, non-crop habitats merit further research focusing on establishing which field margin species are most important and their capacity to support other ecosystem services such as natural pest regulation or even pests.

Living in seasonally dynamic farmland: The role of natural and semi-natural habitats in the movements and habitat selection of a declining bird

Understanding spatiotemporal variations of movements and habitat selection by animals living in changing, heterogeneous environments under increasing human pressure is crucial for biodiversity conservation. We report here on shifts in habitat selection and movements during the breeding and non-breeding periods in a vulnerable and specialist bird, the pin-tailed sandgrouse Pterocles alchata, to understand the importance of remnant natural or semi-natural habitats. We used a 7-year dataset from 91 radio-tracked birds living under two contrasting landscapes: a farmland-dominated area (agricultural landscape) in central Spain and a low-intensive farmland area with natural steppe-like vegetation (mixed landscape) in northern Spain. We found that sandgrouse selected sites of natural vegetation (short shrubs and sparse annual plants) across all periods in the mixed landscape. Birds performed long movements in the agricultural landscape to exploit patchy resources and expanded their distribution during the breeding period, possibly because of an increased scarcity of non-cropped habitats in farmland. During the non-breeding period, sandgrouse used dry arable lands in both landscapes, with birds in the mixed landscape displaying a highly mobile pattern to visit dry arable regions. Dry arable lands become structurally more suitable during winter for seed-eating birds such as sandgrouse that can use ploughed fields and exploit seeds during cereal sowing. Effective conservation measures for specialist birds of farmland should promote a greater availability of non-cropped habitats of natural and semi-natural vegetation to enhance their space use and reproductive opportunities.

Local management and landscape structure determine the assemblage patterns of spiders in vegetable fields

Both field- and landscape-scale factors can influence the predator communities of agricultural pests, but the relative importance and interactions between these scales are poorly understood. Focusing on spiders, an important taxon for providing biological control, we tested the influence of field- and landscape-scale factors on structuring the spider communities in a highly dynamic brassica agroecosystem. We found that local factors (pesticide-use and crop type) and forested landscape significantly influenced the abundance and species richness of spiders, whilst grassland patches significantly affected the spider species richness. Correlation results demonstrated that assemblage patterns of most spider families positively responded to the interplay between local factors and forest patches in the landscape. The spiders abundance was greatest in cauliflower crops surrounded with forest and grassland patches in landscape. Similarly, ordination analyses revealed that organic fields of cauliflower in forested landscapes had a strong positive association with the abundance and species richness of spiders. In contrast, insecticide and synthetic fertilizer-treated fields of Chinese cabbage in landscapes with little non-crop habitat reduced the abundance and species richness of spiders. Our results highlight the extent of interaction between local- and landscape-scale factors, help explain recently reported inconsistent effects of landscape factors on conservation biological control.

Environmental filtering and spillover explain multi-species edge responses across agricultural boundaries in a biosphere reserve

To ensure integrity of protected areas we need to understand how species respond to anthropogenic borders. We investigate, from a metacommunity perspective, the direct and indirect mechanisms by which transformed areas affect distribution patterns of ground-living arthropod assemblages inhabiting an extensive protected area adjacent to fruit orchards in an important biosphere reserve. Arthropods and environmental variables were sampled along transects perpendicular to natural-orchard edges. Influence of distance from orchard boundary, degree of impermeability of the boundary, orchard habitat quality (local scale land-use intensity), and edge-induced changes in local environmental variables on arthropod species richness and composition in non-crop habitats were assessed. Arthropod groups were assessed in terms of habitat fidelity: species associated with natural habitat (stenotopic species), those within crop habitat (cultural species), and those showing no preference for either habitat (ubiquitous species). Spillover resulted in higher cultural species richness near edges, but not higher overall species richness. Environmental filtering was important for stenotopic species composition, which was influenced by edge-induced changes in environmental variables. Ubiquitous species composition was determined by orchard impermeability. Increased orchard habitat quality was associated with higher cultural and ubiquitous species richness. The effects of orchards on assemblages in natural habitats can be variable, but predictable when using species habitat specificity in conjunction with a metacommunity framework. High intensity orchards may act as sink habitats, especially for species that readily disperse between crop and natural habitats. Here we recommend that local buffer strips are > 85 m wide, which will reduce the influence of cultural species spillover on sensitive natural ecosystems.

Tree Swallow selection for wetlands in agricultural landscapes predicted by central-place foraging theory

Abstract Millions of wetland basins, embedded in croplands and grasslands, are biodiversity hotspots in North America’s Prairie Pothole Region, but prairie wetlands continue to be degraded and drained, primarily for agricultural activities. Aerial insectivorous swallows are known to forage over water, but it is unclear whether swallows exhibit greater selection for wetlands relative to other habitats in croplands and grasslands. Central-place foraging theory suggests that habitat selectivity should increase with traveling distance from a central place, such that foragers compensate for traveling costs by selecting more profitable foraging habitat. Using global positioning system (GPS) tags, we evaluated habitat selection by female Tree Swallows (Tachycineta bicolor) at 4 sites containing wetlands and where terrestrial land cover was dominated by grasslands (grass, herbaceous cover) and/or cultivated cropland. We also used sweep-net transects to assess the abundance and biomass of flying insects in different habitats available to swallows (wetland pond margins, grassy field margins, and representative uplands). As expected for a central-place forager, GPS-tagged swallows selected more for wetland ponds (disproportionate to availability), and appeared to increasingly select for wetlands with increasing distance from their nests. On cropland-dominated sites, insect abundance and biomass tended to be higher in pond margins or grassy field margins compared to cropped uplands, while abundance and biomass were more uniform among sampled habitats at sites dominated by grass and herbaceous cover. Swallow habitat selection was not clearly explained by the distribution of sampled insects among habitats; however, traditional terrestrial sampling methods may not adequately reflect prey distribution and availability to aerially foraging swallows. Overall, our results underscore the importance of protecting and enhancing prairie wetlands and other non-crop habitats in agricultural landscapes, given their disproportionate use and capacity to support breeding swallow and insect populations.

Spatiotemporal changes in landscape crop composition differently affect density and seasonal variability of pests, parasitoids and biological pest control in cabbage

Declines in functional biodiversity, caused by changing structure and composition of agricultural landscapes, endanger the provision and stability of important ecosystem services, such as biological pest control. Understanding how spatiotemporal landscape changes affect the dynamics of pests, natural enemies and their activity can help safeguard and improve pest control in crops. Here, we tested the influence of spatial and temporal differences in landscape composition of crops (landscape-wide crop rotation diversity and % pest host crops) on the density and seasonal variability of cabbage pests, parasitoids and rates of aphid parasitism and predation. We also tested whether low seasonal variability of pests and parasitoids translates into stable and high pest control, reduced crop damage and higher yields. We show that landscapes with diverse crop rotations increased aphid parasitism, but also leaf-chewing pest density and seasonal stability. Leaf-chewing pest density decreased with increasing % host crops from year to year, suggesting a dilution effect. However, parasitoid density increased in these landscapes. We found no relationship between predation or parasitism and crop damage or yield. Further, stable parasitoid populations led to more stable parasitism rates. These findings highlight that impacts of spatially and temporally changing landscapes are pest- and enemy-specific, and tradeoffs for landscape management may occur. Appropriately managing the diversity and composition of arable crops in farmed landscapes may help influence species occurrences, without converting fertile land to non-crop habitat.

Early planting, management of edges and non-crop habitats reduce potyvirus infection in maize

Viruses are a limiting factor in maize production areas around the world. The knowledge of the interactions between agroecosystems and the virus-vector-host system is limited, but a landscape-scale approach could help fill this gap. In this study, we show how the use of multiple spatial scales, i.e. 200, 500 and 1000 m, is a novel methodology for explaining the incidence of two closely related potyviruses: maize dwarf mosaic virus and sugarcane mosaic virus. To determine the factors involved in virus incidence, we recorded the proportion of surrounding crops and non-crop habitats at the landscape scale and, at the field scale, we recorded the planting date, the maize field area, the crop rotation and the weed diversity in the edges. In addition, we estimated the numbers of aphids with sticky yellow traps. Virus incidence in maize and in alternative grass hosts was determined by DAS-ELISA. Generalised linear mixed models were fitted using the multimodel inference method. The results showed that the most predictive model for the incidence of both potyviruses was at a scale of 200 m, but for the aphid abundance, it was at a scale of 500 m. Maize dwarf mosaic virus incidence was most affected by field management, and sugarcane mosaic virus by landscape variables. The planting date and the weed diversity in the edges were the field variables with the highest positive effects on both potyviruses. Moreover, both viruses were positively related to the abundance of aphids, and maize dwarf mosaic virus was only related to the cover of Johnson grass in the edges. Non-crop habitats had negative effects on potyvirus incidence at all spatial scales, showing that biodiversity in the landscape decreases the incidence of viruses. Here, we show that the early planting, the management of edges and the presence of non-crop habitats are key factors.

Do non-crop areas and landscape structure influence dispersal and population densities of male olive moth?

The permeability of the crop surroundings to pests and the landscape structure can influence pest dispersal between crop patches as well as its abundance within the crop. In this work, we analyzed the dispersal of the olive moth Prays oleae (Bernard) throughout the olive grove surroundings and their abundance within the crop following three approaches: (i) pollen grains settled on bodies of olive moths collected in olive groves were identified and compared with flora occurring on the surrounding patches; (ii) the capability of P. oleae males to penetrate non-crop patches was analyzed (iii) the effect of the landscape structure on the abundance of the three generations of the olive moth was studied. Pollen grains of scrubs and other trees occurring in the crop surroundings, such as Cistus sp., Quercus sp., Juniperus-type or Pinaceae were identified on P. oleae bodies suggesting that P. oleae penetrates into non-crop habitats. Additionally, woody and, to a lesser degree, herbaceous patches, did not constitute barriers for P. oleae. Finally, more complex and heterogeneous patches presented lower numbers of captures of P. oleae. These results give new insights into the movements of the olive moth in the olive grove surroundings and suggest that the management of non-crop areas could influence this pest abundance.

Noncrop features and heterogeneity mediate overwintering bird diversity in agricultural landscapes of southwest China.

Farmland birds are of conservation concerns around the world. In China, conservation management has focused primarily on natural habitats, whereas little attention has been given to agricultural landscapes. Although agricultural land use is intensive in China, environmental heterogeneity can be highly variable in some regions due to variations in crop and noncrop elements within a landscape. We examined how noncrop heterogeneity, crop heterogeneity, and noncrop features (noncrop vegetation and water body such as open water) influenced species richness and abundance of all birds as well as three functional groups (woodland species, agricultural land species, and agricultural wetland species) in the paddy‐dominated landscapes of Erhai water basin situated in northwest Yunnan, China. Birds, crop, and noncrop vegetation surveys in twenty 1 km × 1 km landscape plots were conducted during the winter season (from 2014 to 2015). The results revealed that bird community compositions were best explained by amounts of noncrop vegetation and compositional heterogeneity of noncrop habitat (Shannon–Wiener index). Both variables also had a positive effect on richness and abundance of woodland species. Richness of agricultural wetland species increased with increasing areas of water bodies within the landscape plot. Richness of total species was also greater in the landscapes characterized by larger areas of water bodies, high proportion of noncrop vegetation, high compositional heterogeneity of noncrop habitat, or small field patches (high crop configurational heterogeneity). Crop compositional heterogeneity did not show significant effects neither on the whole community (all birds) nor on any of the three functional groups considered. These findings suggest that total bird diversity and some functional groups, especially woodland species, would benefit from increases in the proportion of noncrop features such as woody vegetation and water bodies as well as compositional heterogeneity of noncrop features within landscape.

Short Communication: Landscape composition alters parasitoid wasps but not their host diversity in tropical agricultural landscapes

Abstract. Syahidah T, Rizali A, Prasetyo LB, Pudjianto, Buchori D. 2020. Short Communication: Landscape composition alters parasitoid wasps but not their host diversity in tropical agricultural landscapes. Biodiversitas 21: 1702-1706. The diversity of parasitoid wasps and their hosts in an agricultural landscape is affected by crop management and habitat conditions around crop fields. The composition of agricultural landscapes that are dominated by non-crop or natural habitats are assumed to be able to support the presence of parasitoid wasps as biological control of pests. The aim of this study was to investigate the effect of landscape composition on the diversity of parasitoid wasps and their hosts in agricultural landscapes. The research observations were conducted on six fields of long-bean cultivation located in Bogor District, West Java Province, Indonesia. Parasitoid wasps were collected by hand-collecting of their hosts (lepidopteran larvae) within 60 m distance transect to each long-bean field. In total, 17 species of parasitoid wasps and 12 species of lepidopteran larvae were found from all agricultural landscapes. A parasitoid wasp, Microplitis manilae was found in all long-bean fields (except Bantarjaya) and only parasitized the tobacco cutworm (Spodoptera litura). The tomato looper, Chrysodeixis chalcites had the highest associated parasitoids and was also parasitized by Braconidae sp5 which was also a parasitoid of S. litura. Based on the analysis results, the patch numbers of natural habitats had a positive effect on the diversity of parasitoid wasps and had no effect on the diversity of lepidopteran larvae. In conclusion, landscape compositions with patchy natural habitats have an important role to preserve beneficial insects and maintain ecosystem services in tropical agricultural landscapes.

Distribution of ecosystem services within oilseed rape fields: Effects of field defects on pest and weed seed predation rates

Frequent extreme weather events, which jeopardize agriculture by affecting crop health, characterize the ongoing climate change. Temporary patches where sown plants are poorly developed (hereafter “field defects”) are likely to increase with climate change and can be colonized by other plant species. Although perennial non-crop habitats can act as refuges for beneficial insects in agricultural landscapes and increase ecosystem services (ESs) in neighbouring arable fields, the relevance of field defects is unknown. Here, we quantified two ESs (pest and weed seed predation) in field defects within oilseed rape crops and related the ES levels with the activity-density of ground beetles and temperature. In 10 fields, we used artificial caterpillars made of plasticine and seed cards of two weed species (Taraxacum sp. and Stellaria sp.) to quantify the ESs in two sampling periods (spring and summer) and three habitat types: field defects, crops grown in standard conditions (field interiors) and crop-defect boundaries. Ground beetles were sampled using pitfall traps and classified into feeding guilds and body-size classes. Insects and mammals were the main pest predators, and predation increased in summer but did not differ among habitats. Seed predation rates for both species were significantly higher in summer. Predation upon Taraxacum seeds was higher in the field interiors, whereas the predation rate upon Stellaria seeds was significantly higher in the field interiors and defects compared to that in the crop-defect boundaries. The predation rate by insects increased with the activity-density of the medium- and large-sized carnivorous carabids, whereas the seed predation rate for both weed species was positively related to the activity-density of medium-sized herbivorous carabids. Finally, the mean and maximum temperatures were negatively linked to the predation rates on artificial caterpillars and seeds of Taraxacum, respectively. Our results suggest that these ephemeral habitats are not related to a strong decrease in ecosystem services; thus, field defects may not cause substantial changes in ES provisioning. We confirmed that ground beetles are important providers of both investigated ESs and showed that microclimatic conditions might play an important role in the regulation of ESs in agroecosystems.