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Agricultural intensification is a major driver of biodiversity loss, but the majority of studies highlighting these threats come from industrialised agriculture in temperate countries of the global North. However, more than 30% of global food production is produced by smallholder farmers, particularly in Africa. We know very little about the impact of these farming practices on arthropod communities and associated ecosystems in dryland agroecosystems. We investigated the trophic group composition of arthropod communities (detritivorous, herbivorous, predatory & mixed feeders) and levels of associated ecosystem functions in replicated maize fields, paired adjacent natural bushveld habitats and the edge habitats between them in north-eastern Namibia and central-eastern Botswana during the dry and wet seasons. Predator activity densities differed significantly between habitats depending on the season, with higher numbers in natural habitats in the wet season but lower numbers in the dry season compared to maize fields. In general, edge habitats had higher numbers of predators than the other habitats. Predator attack rates on artificial caterpillars in both seasons and dung removal in the wet season were higher in habitats with natural vegetation (natural and edge). However, dung removal in the dry season and herbivory in the wet season were highest in the maize fields, the latter due to high level of fall armyworm infestation. Wet season multifunctionality was higher in natural habitats in Botswana, and to a lesser extent in Namibia, than in maize fields. Smallholder agriculture is not detrimental to decomposers, herbivores and mixed feeders compared to adjacent natural habitats, but may be detrimental to the provision of some ecosystem services. These results highlight the challenge of sustainably managing dryland agricultural land that is marginal for crop production, while providing smallholders with an optimal environment to benefit from the ecosystem services associated with arthropod communities. New conservation agriculture practices need to support the production of higher and more stable yields over time, while maintaining the limited impact of smallholder agriculture on biotic communities. • Dryland agriculture does not reduce trophic groups compared to natural habitats. • Predator attacks & dung removal (wet season) were higher in natural habitats. • Dung removal (dry season) & herbivory (wet season) were higher in maize fields. • Wet season multifunctionality was highest in natural habitats. • Smallholder agriculture reduced multifunctionality, but not arthropod numbers. [ABSTRACT FROM AUTHOR]

The contribution of bird predation to the spatial variations in insect herbivory remains imperfectly understood, especially in Arctic ecosystems. We experimentally tested the hypothesis that the differences in insect herbivory between tundra and forest biomes, and between plant life-forms in these biomes, are associated with differences in the intensity of bird predation on defoliating insects. We observed substantial variation in herbivory (0% to 20% of foliage lost) among nine forest, mountain tundra, and lowland tundra sites in the Kola Peninsula (northwestern Russia) and among five woody plant species, but we found no consistent differences in herbivory between biomes and between plant life-forms. Bird attacks on artificial caterpillars were tenfold more frequent in forest than in tundra, while bird exclusion effects on herbivory did not differ between biomes, and the intensities of bird predation measured by these two methods were not correlated. Bird exclusion led to increases in insect herbivory, and this effect was significant in trees and tall shrubs but was not significant in dwarf shrubs in either forest or tundra sites. Bird predation, as measured in bird exclusion experiments, increased with an increase in the level of foliar damage inflicted by insects in forests but not in tundra habitats. We conclude that bird predation generally decreases plant losses to insects in both forest and tundra habitats, but birds are unlikely to shape the spatial patterns of plant losses to insects in Arctic ecosystems. [ABSTRACT FROM AUTHOR]

In agricultural landscapes, semi-natural habitats can support populations of beneficial species, such as natural enemies. Using artificial caterpillars made of plasticine, we compared arthropod and vertebrate predation rates in wheat fields adjacent to hedgerows or spontaneous grass margins in two contrasting agricultural landscapes. Overall, 25.3% of the caterpillars were attacked after 24 h, mainly by arthropods (67.1%). Predation rates in the heterogeneous and homogeneous landscapes were similar (mean ± SE; 24.9% ± 3.0% vs 25.7% ± 3.6%, n = 10 per landscape). However, we found a significant interaction between the margin and landscape type. Total (arthropods + vertebrates) predation rates were significantly higher in wheat fields next to hedgerows than in conventional wheat fields with grass margins in the homogeneous landscape (33.7% ± 4.5% vs 17.7% ± 2.5%, n = 5 per margin type and landscape), while no difference between predation rates in the two margin types was detected in the heterogeneous landscape. Total and vertebrate predation rates were positively affected by plant species richness, which suggest that one of the mechanisms through which hedgerows can support higher predator activity than spontaneous grass margins, particularly in homogeneous agricultural landscapes, is by providing higher plant diversity. Our results suggest that in simple landscapes, hedgerows may act as habitat islands of high conservation value for biodiversity, having a disproportionate value compared to hedgerows in landscapes that include forest fragments and other semi-natural habitats. • We recorded predation in two margin types in two contrasting agricultural landscapes. • Hedgerows enhanced predation in wheat fields in the homogeneous landscape. • Predation in the two margin types did not differ in the heterogeneous landscape. • Plant species richness and diversity partly accounted for those differences. • Hedgerows may be habitat islands of high conservation value in simple landscapes. [ABSTRACT FROM AUTHOR]

Biological control by predators of insect pests is an important benefit of biodiversity, having a contribution to agricultural production. By preying on crop infesting insect pests, predatory arthropods and birds can provide an important ecosystem service. They support agricultural productivity, boosting crop yield and reducing demand for pesticides expense. Habitat quality of land use types, i.e., explained by vegetation cover, can impact the provision of ecosystem services thereby influencing the prevalence of the predators and their predation rates. In order to better understand the level of insect pest control service by predators, we conducted a field experiment to investigate levels of predation, using an attack on artificial caterpillars in response to land use types varied in vegetation cover. We found the attack rate by arthropods was more consistent across land use types than by birds, and the attack by birds was higher in modified land use types with sparse woody vegetation. Moreover, the attack rate for birds showed a decreasing tendency with increasing woody species richness, cover and stem density, while it showed less variation for arthropods. We conclude that biological control by birds is more effective in habitats with simplified vegetation cover than for arthropods in agricultural landscapes. Therefore, we recommend the prevalence of shade trees and small forest patches in agricultural landscapes for supporting the increased levels of insect pest control services provided by predatory birds and arthropods. • Woody vegetation provides habitat for predatory birds and arthropods. • The quality of woody cover may vary depending on the type of land use. • Crop pest insects are the main causes of reductions in crops productivity. • Predatory arthropods and birds can remove pest through biological control. • Predation rates of arthropods and birds may vary depending on woody cover. [ABSTRACT FROM AUTHOR]

Humankind draws important benefits from large‐scale ecological processes termed ecosystem services, yet the status of several of them is declining. Reliable monitoring methods are essential for tracking the status of ecosystem services. Predation is the mainstay of natural pest control, a key ecosystem service. We used green plasticine caterpillars to monitor predation pressure, and to obtain baseline data on predator activity in transgenic Bt versus non‐Bt maize fields in Old and New World countries. Predation pressure was measured at ground and canopy levels using an identical, small‐plot experimental design in four European countries (Denmark, Slovakia, Romania and Italy) and Argentina. Total predation rate in maize was 11.7%d−1 (min. 7.2%d−1 in Argentina, max. 29.0%d−1 in Romania). Artificial caterpillars were attacked both by invertebrates (mostly chewing insects with 42.0% of the attack marks, and ants with 7.1%, but also predatory and parasitoid wasps, spiders and slugs), and vertebrates (small mammals 25.5%, and birds 20.2%). Total predation at ground level (15.7%d−1) was significantly higher than in maize canopies (6.0%d−1) in all countries, except Argentina. We found no significant differences between predator pressure in Bt versus non‐Bt maize plots. The artificial caterpillar method provided comparable, quantitative data on predation intensity, and proved to be suitable for monitoring natural pest control. This method usefully expands the existing toolkit by directly measuring ecological function rather than structure. [ABSTRACT FROM AUTHOR]

Sentinel prey (an artificially manipulated patch of prey) are widely used to assess the level of predation provided by natural enemies in agricultural systems. Whilst a number of different methodologies are currently in use, little is known about how arthropod predators respond to artificially manipulated sentinel prey in comparison with predation on free‐living prey populations. We assessed how attack rates on immobilized (aphids stuck to cards) and artificial (plasticine lepidopteran larvae mimics) sentinel prey differed to predation on free‐moving live prey (aphids). Predation was assessed in response to density of the common invertebrate predators, a foliar‐active ladybird Harmonia axyridis (Coleoptera: Coccinellidae), and a ground‐active beetle Pterostichus madidus (Coleoptera: Carabidae). Significant increases in attack rates were found for the immobilized and artificial prey between the low and high predator density treatments. However, an increased predator density did not significantly reduce numbers of free‐living live aphids included in the mesocosms in addition to the alternate prey. We also found no signs of predation on the artificial prey by the predator H. axyridis. These findings suggest that if our assessment of predation had been based solely on the foliar artificial prey, then no increase in predation would have been found in response to increased predator density. Our results demonstrate that predators differentially respond to sentinel prey items which could affect the level of predation recorded where target pest species are not being used. [ABSTRACT FROM AUTHOR]

In order to estabilish strategies for pest control it is extremely important to know the structure of the phytopathogens and their numerical density evolution. Agriculture is a dynamic system that continually changes to changing crop production practices. Integrated pest management (IPM) must continually change to meet pest management challenges. IPM is a continuum that will change with time. Every farmer practices some type of IPM, as long as they make progress to better in management. As new pest control techniques are discovered, the producer and crop advisor must adapt their pest control program to reflect these changes. Starting from the concept that IPM have to ensure a very low level of pesticides waste production, we have to take in consideration the relationship between usefull entomofauna and harmful species. For this reason it is necessary to establish a monitoring system of biodiversity for each culture. There are a lot of methods for monitoring pest population, but for this study we chosed a less usual named methode with artificial caterpillars. This method has given use differences between day and night activity of the entomofauna in three different ecosystems in forrest patch, pasture patch, and a protected area. The result obtained during this study showed that the entomofauna activity is different during day and night time, and type of artificial caterpillars. During the study predators reacted much more to the red colored caterpillars than to the green colored ones, and also we found significant differences between the three different ecosystems used. [ABSTRACT FROM AUTHOR]

Environmental stressors and changes in land use have led to rapid and dramatic species losses. As such, we need effective monitoring programs that alert us not only to biodiversity losses, but also to functional changes in species assemblages and associated ecosystem processes. Ants are important components of terrestrial food webs and a key group in food web interactions and numerous ecosystem processes. Their sensitive and rapid response to environmental changes suggests that they are a suitable indicator group for the monitoring of abiotic, biotic, and functional changes. We tested the suitability of the incidence (i.e. the sum of all species occurrences at 30 baits), species richness, and functional richness of ants as indicators of ecological responses to environmental change, forest degradation, and of the ecosystem process predation on herbivorous arthropods. We sampled data along an elevational gradient (1000–3000 m a.s.l.) and across seasons (wetter and drier period) in a montane rainforest in southern Ecuador. The incidence of ants declined with increasing elevation but did not change with forest degradation. Ant incidence was higher during the drier season. Species richness was highly correlated with incidence and showed comparable results. Functional richness also declined with increasing elevation and did not change with forest degradation. However, a null-model comparison revealed that the functional richness pattern did not differ from a pattern expected for ant assemblages with randomly distributed sets of traits across species. Predation on artificial caterpillars decreased along the elevational gradient; the pattern was not driven by elevation itself, but by ant incidence (or interchangeable by ant richness), which positively affected predation. In spite of lower ant incidence (or ant richness), predation was higher during the wetter season and did not change with forest degradation and ant functional richness. We used path analysis to disentangle the causal relationships of the environmental factors temperature (with elevation as a proxy), season, and habitat degradation with the incidence and functional richness of ants, and their consequences for predation. Our results would suggest that the forecasted global warming might support more active and species-rich ant assemblages, which in turn would mediate increased predation on herbivorous arthropods. However, this prediction should be made with reservation, as it assumes that the dispersal of ants keeps pace with the climatic changes as well as a one-dimensional relationship between ants and predation within a food-web that comprises species interactions of much higher complexity. Our results also suggested that degraded forests in our study area might provide suitable habitat for epigaeic, ground-dwelling ant assemblages that do not differ in incidence, species richness, functional richness, composition, or predation on arthropods from assemblages of primary forests. Most importantly, our results suggest that the occurrence and activity of ants are important drivers of ecosystem processes and that changes in the incidence and richness of ants can be used as effective indicators of responses to temperature changes and of predation within mega-diverse forest ecosystems. [ABSTRACT FROM AUTHOR]

The effectiveness of natural enemies to control pests can be enhanced through habitat manipulation. However, due to the differences in their ecology, generalist and specialist species may respond differently to the same manipulation. Moreover, interactions among natural enemies (i.e. cannibalism, intraguild predation, hyperparasitism) may complicate the assumption that a higher density of natural enemies would increase the level of biological control. We investigated the natural enemy guild composition and the predation rate along flower vs. grass margins at the edge of winter wheat ( Triticum aestivum) fields in Denmark. Natural enemies were sampled by pitfall trapping and by suction sampling; predation intensity was measured using two different sentinel prey methods: artificial caterpillars made of plasticine, and sentinel aphid colonies. Specialist and generalist species responded differently to the two margin types: specialists (mostly parasitic wasps) were attracted by the flower margins, while generalists (ground beetles, rove beetles and spiders) were more active in grass margins. The number of artificial caterpillars attacked was significantly greater in grass margins (mean = 48.9%, SD = 24.3) than in flower margins (mean = 30.7%, SD = 17.4). We found a significant positive relationship between the number of artificial caterpillars attacked by chewing insects, and activity density for large (≥15 mm) ground beetles. Predation of sentinel aphids in wheat fields did not vary significantly in relation to margin type. Our results suggest that flowering margins may be beneficial for canopy-active specialist natural enemies, but grassy margins are more useful for ground-active generalist predators. [ABSTRACT FROM AUTHOR]

Predation pressure is essential in regulating population dynamics of herbivorous insects. We used artificial caterpillars (25 × 4 mm) made from brown-or green-coloured plasticine to compare predation pressure between countryside and near-natural rain-forest habitat in the Gulfo Dulce region (Costa Rica). Within each habitat, 162 caterpillars were placed randomly on different substrates along a 1200-m transect and at heights between 0.5 and 2.0 m. Artificial caterpillars were inspected at 24-h intervals for 3 consecutive days. Predation pressure was almost twice as high for countryside (mean attack frequency per capita: 1.11 ± 0.08 SE) compared with rain forest (0.66 ± 0.07 SE). In both habitats arthropods emerged as chief predator group, followed by birds. Attacks by non-volant mammals were very rare and restricted to rain-forest sites. In the countryside, bird attacks were more than four times as common as in forest, indicating a change in their relative importance across habitats. [ABSTRACT FROM PUBLISHER]

Pest suppression by natural enemies is an important ecosystem service, which is a valuable resource to poor smallholders in developing countries. Diverse natural enemy assemblages of arthropod predators and parasitoids are documented in various regions in Africa, but our knowledge of their impact on herbivores in agroecosystems remains limited. We conducted experiments in cotton, Gossypium hirsutum L. ( Malvaceae), under typical local agronomic practices in Uganda to assess levels of predation pressure ascribed to natural enemies. We measured predation rates on artificial caterpillars made of plasticine glued to cotton plants. Predation pressure on cotton fields varied between 1.96 and 4.1% per day, but was not significantly influenced by cotton treatments (insecticide/no insecticide, monocropping/intercropping with Phaseolus spp.). Predation pressure in non-crop habitats adjacent to cotton fields was up to 12× higher than in the fields. Marks left on the artificial caterpillars revealed that arthropods and birds were largely accountable for predation in cotton fields, whereas arthropods and small mammals were dominant in non-cultivated habitats. [ABSTRACT FROM AUTHOR]