Seed Predation Research Articles

Frequency-dependent seed selection by rodents: Response to seed tannins and sizes

Seed predation by rodents relies on the abundance of available seeds and seed traits like sizes and tannin-content. Here, by tracking the fates of 2400 tagged seeds of two sympatric tree species Quercus wutaishanica and Corylus heterophylla with varying size and tannin content, we assessed rodents’ preference for specific seed traits. Meanwhile, we set the ratio of large to small seeds within species as 9:1, 7:3, 5:5, 3:7, and 1:9, respectively, to examine rodent behavior in response to seed relative frequencies. We found that: 1) rodents preferentially hoarded C. heterophylla seeds with lower-tannins after dispersal while Q. wutaishanica seeds with higher-tannins are more often eaten in situ or after dispersal. Peeling seed coat is an adaptive strategy for rodents to avoid high tannins, particularly for Q. wutaishanica. 2) Rodents prioritize small seeds over large ones for Q. wutaishanica whereas significant differences were not observed for C. heterophylla. Rodents commonly eat small seeds after successful dispersal and prefer to hoard larger ones over long distances. 3) Positive frequency-dependent selection was observed for both seed types. Our results suggest that the selection of seeds by rodents is determined by seed tannins and sizes, and changes in seed size frequencies could alter the interaction between trees and rodents from predation towards mutualism.

Effects of Seed Size and Frequency on Seed Dispersal and Predation by Small Mammals.

Frequency-dependent predation is common in predator-prey interactions. Size is an important characteristic of seeds and is crucial in the regeneration stage of plant seeds. However, the frequency dependence of animal predation on seed size has not been reported. In this study, we conducted a field experiment and used different sizes of Liaodong oak (Quercus wutaishanica) seeds to test the frequency dependence of intraspecific seed size selection in rodents. We used the number ratio of large to small seeds as the frequency. The results show that the rate of small seeds being eaten in situ was significantly higher than that of large seeds (p < 0.05). The rates of different-sized seeds being eaten after removal decreased with increasing frequencies, and there was no significant difference between frequencies except for 1:9 and 9:1. The rates of large seeds being scatter-hoarded were significantly higher than those of small seeds at different frequencies (p < 0.05). The eating distances after removal of large seeds were significantly longer than those of small seeds at the same frequencies (p < 0.05). Furthermore, the scatter-hoarding distances of large seeds were significantly longer than those of small seeds at three frequencies (1:9, 3:7, and 9:1) (p < 0.05). That is, rodents consumed more small seeds in situ, dispersed and scatter-hoarded more large seeds, and dispersed large seeds over longer distances. Rodents exhibited a negative frequency dependence for small seeds and a positive frequency dependence for large seeds on being eaten in situ. Moreover, rodents exhibited a negative frequency dependence for large seeds and a positive frequency dependence for small seeds on being eaten after removal and scatter-hoarding. These results reveal the frequency dependence of rodent selection on seed size and provide new insights into animal-mediated seed dispersal and the regeneration of plant populations.

Effect of treatment with thiamethoxam and cyantraniliprole on the germination and storage of forest tree seeds

ABSTRACT: Seed predation is a problem that limits the use of direct sowing of tree species, and it is necessary to develop studies involving products used in seed treatment. The objectives of this study were to evaluate the effects of treatment with insecticides on the storage and germination of seeds of six forest species. Seeds were treated with thiamethoxam and cyantraniliprole and germinated on paper and sand substrates at 25 °C under constant light. For storage, the seeds were treated and analyzed at 0, 3 and 6 months. For both tests, the following variables were evaluated: germination, mortality, hard seeds, abnormal seedlings, average length of shoot and primary root, and germination speed index (GSI). For Senna multijuga, treatment with insecticides had no effect. Peltophorum dubium and Enterolobium contortisiliquum showed positive effects of the treatments on seedling vigor and development, while Guazuma ulmifolia displayed a negative effect on primary root length. Bowdichia virgilioides and Hymenaea courbaril seeds were sensitive to the treatments. It is possible to treat and store P. dubium and E. contortisiliquum seeds with thiamethoxam for up to six months.

Frugivory and seed predation of fishtail palm (Caryota mitis Lour.) on the remote oceanic island of Narcondam, India

Abstract Oceanic islands, due to their evolutionary history and isolation, play a dual role of having high endemicity and being vulnerable to extinctions, with most known extinctions occurring on islands. Plant–animal interactions are particularly important on islands, as island systems generally have low redundancy and are more vulnerable to disruption either via extinction or by invasive species. Here, we examined the fruit removal and seed predation of a keystone palm, Caryota mitis, on Narcondam, a remote oceanic island. The island endemic Narcondam Hornbill (Rhyticeros narcondami) was the sole seed disperser of the palm (90 hours; N = 15 trees), with mean (± SE) visitation rate being 0.23 (± 0.06) individuals per hour and fruit removal rates of 3.5 (± 1.5; range: 0–16) fruits per visit, indicating a lack of redundancy in seed dispersal of the palm on this island. Whereas the invasive rodent, Rattus cf. tiomanicus, was the sole predator of palm seeds (N = 15 individual fruiting palms, 416 trap nights). Overall, 17.1% of the seeds placed (N = 375 seeds) were removed. Seeds placed under and away from the canopy, and at different densities (2 plots with 10 seeds each; 1 plot with 5 seeds, respectively), showed similar removal rates. This indicates density-independent seed predation and the lack of safe regeneration sites for Caryota mitis, with potential deleterious effects on subsequent stages of the ‘seed dispersal cycle’. Here, from a data-deficient site, we provide baseline information on the plant–frugivore interaction of a keystone palm and the potential impacts of an invasive rodent.

Biochar-Based Seed Coating as an Effective Strategy to Reduce Seed Predation When Restoring Forests on Degraded Land

Biochar-Based Seed Coating as an Effective Strategy to Reduce Seed Predation When Restoring Forests on Degraded Land

A Faboideae-Specific Floral Scent Betrays Seeds to an Important Granivore Pest.

Seed predation by insect herbivores reduces crop production worldwide. Foraging on seeds at pre-dispersal generally means that females need to find the suitable host plant within a relatively short timeframe in order to synchronize larval development with seed production. The mechanistic understanding of host finding by seed pests can be harnessed for more sustainable pest management strategies. We here studied the chemical communication between the bean bug Riptortus pedestris, a major pest of legumes, and several crop species and cultivars in the Fabaceae. Via a comparative chemical analysis, we found that 1-octen-3-ol is the principal constituent of the floral scents of most species tested in the subfamily Faboideae, including soybean and faba bean. With field trapping and laboratory bioassays, including electroantennography, we further revealed that this compound can be perceived, and stimulate attraction responses, by R. pedestris nymphs and adults. The addition of 1-octen-3-ol to pheromone traps might therefore improve trapping efficacy for controlling populations of this important granivore pest on legumes.

Does increasing the diversity of seeds broadcast for restoration alter post‐dispersal seed predation and its community‐determining effects?

Abstract Native seeds broadcast for restoration are often consumed by predators before they can germinate. However, it is unclear how the composition of a seed mix affects seed predation. We excluded vertebrates from small plots seeded with native grassland plants to evaluate how seed diversity affects predation. There were two seeding treatments: a less diverse mix with a focal cohort of eight species on which we focused our analyses, and a more diverse mix that consisted of the focal cohort plus eight additional species. The focal cohort experienced greater predation when dispersed with the additional species, but this effect was unevenly distributed throughout the focal cohort. The species of the focal cohort that experienced the greatest increase in predation when in the high‐diversity treatment were also the ones favoured by predators when in the treatment without additional species. This suggests that when more species of palatable seed are available in a dispersed seed patch, predators may exert a stronger community‐filtering effect on such a seed patch. Increasing the number of species dispersed together for land stewardship efforts may increase predation of these seeds, which is a concern if their dispersal is intended to restore native plant diversity. We recommend strategies to minimize this potential detriment, such as staggering seed dispersal over time, for practitioners who seek to disperse a high diversity of seeds for native restoration.

Density-Dependent Seed Predation of Quercus wutaishanica by Rodents in Response to Different Seed States.

The predation and/or dispersal of Quercus seeds by rodents play an important role in the creation of the tree species. The present study examined the effects of community habitats on the predation and dispersal of Quercus wutaishanica seeds by rodents. We released seeds with densities set at 2, 4, 8, 16, and 32 seed square meter with litter cover, soil burial, and bare ground in the Liupan Mountains National Nature Reserve in the Ningxia Hui Autonomous Region, northwest China. The results showed that (1) the litter cover and soil burial significantly increased the seed survival probability compared with bare ground treatments, especially the predation in situ (PIS) (p < 0.05). Both the scatter hoarding (SH) and larder hoarding (LH) for litter cover and soil burial were significantly increased compared with bare ground (p < 0.05). (2) The large seeds are preferentially predated after dispersal and their long-distance dispersal (>5 m) was significantly greater than that of small seeds (p < 0.05), while small seeds are more likely to be preyed on in situ or during short-distance dispersal (<3 m). (3) The Q. wutaishanica seed predation by rodents increased at a high density rather than at a low density, indicating a negative density-dependent predation. These findings provide insights into the ecological characteristics of Quercus tree regeneration and shed light on the coexistence between rodents and different-sized seeds.

Temporal Variation in Boxelder Seed Predation by Small Mammals

Acer negundo (Boxelder) is a common tree in eastern North America. Fruits are paired samaras that mature in late summer but persist on trees for months. We examined temporal variation in predation rates by small mammals by attaching samaras to sewing bobbins in a forest in northeastern Wisconsin. We placed samaras in groups of 5 along transects and checked them regularly across 2 fall and 2 spring seasons to determine seed fates. Of the 6702 seeds, 15.26% were consumed, 81.41% were left intact, and 3.33% were aborted. Predation rates were higher in fall than in spring. Granivorous mammals did not secondarily disperse seeds but instead acted solely as seed predators. Releasing seeds over a longer period of time than other species of maples allows trees to increase seed survival by experiencing varying soil conditions and predation rates. Retained sterile fruits may act as decoys that decrease predation rates.

Tree density-dependence effects on seed dispersal of a large-seeded tropical tree

Abstract One of the biggest issues in plant ecology is determining the interaction outcome between seeds and scatter-hoarding rodents because the latter has a dual role as dispersers and predators of seeds. Density-dependence contexts involving resource abundance largely influence the outcome of this interaction. Here, we investigated how the variation in the density of a large-seeded tropical tree (Joannesia princeps Vell) affects its probability of seed removal, consumption, dispersal, and burial by a neotropical rodent (Dasyprocta azarae Lichtenstein). We tested whether the elevated resource availability in high tree density areas would cause scatter hoarder’s satiation by decreasing seed removal and consumption (predator satiation hypothesis) or increasing seed dispersal and burial (predator dispersal hypothesis). We tracked the fate of 461 seeds in 14 plots with distinct J. princeps abundances inside a large Atlantic Forest fragment. We used spool-and-line tracking and camera trappings to determine seed fate and identify interacting animals. Agouti was the only species removing J. princeps seeds. Tree density benefitted J. princeps by increasing seed dispersal through buried seed but not affecting seed removal and consumption. This result shows how density-dependent contexts, such as tree density, may alter seed fate in seed–rodent interactions supporting future studies aiming to reestablishing seed dispersal functions in Atlantic Forest fragments.

La depredación de semillas nativas y no-nativas varía en plantaciones de pino del noroeste de la Patagonia

Human disturbances can cause functional alterations in ecosystems, affecting key interactions such as those between plants and animals. For example, post-seed dispersal predation determines plant establishment in many terrestrial ecosystems and can have positive or negative effects on plant community composition, which can, then, influence ecosystem structure and functionality. However, seed predation can be altered in modified environments, with consequences on the establishment and dispersal of native and non-native plants. The objective of this study was to evaluate the post-dispersal predation of native and non-native seeds at different spatial scales in modified environments: pine plantations, clearcut areas and native forests in Isla Victoria, northwestern Patagonia (Argentina). We used a cafeteria-type experiment offering native and non-native seed species in each habitat and measured the vegetation cover around each seed offering area to assess the effect of microsite characteristics. After evaluating predation in the three environments, we only found that there is a greater preference for predation of native seeds in pine forest plantations. On the other hand, we identified that vegetation cover at ground level (strongly correlated with the type of environment) keeps a positive relationship with seed predation. This study shows that seed predation of native and non-native plants could be driven in part by microsite characteristics (greater plant cover = greater seed predation), perhaps through generating refuge (safe site) for the main seed predators of these forests (i.e., rodents). Forest conservation, management and restoration strategies must consider the short- and long-term dynamics of a post-intervention restoration site with the aim of creating an environment conducive to native forest regeneration.

The potential for floral evolution in response to competing selection pressures following the loss of hawkmoth pollination in Ruellia humilis.

In the absence of hawkmoth pollinators, chasmogamous (CH) flowers of Ruellia humilis self-pollinate by two secondary mechanisms. Other floral visitors might exert selection on CH floral traits to restore outcrossing, but at the same time preferential predation of CH seeds generates selection to increase the allocation of resources to cleistogamous (CL) flowers. To assess the potential for an evolutionary response to these competing selection pressures, we estimated additive genetic variances ( ) and covariances for 14 reproductive traits and three fitness components in a Missouri population lacking hawkmoth pollinators. We found significant for all 11 floral traits and two measures of resource allocation to CL flowers, indicating the potential for a short-term response to selection on most reproductive traits. Selection generated by seed predators is predicted to increase the percentage of CL flowers by 0.24% per generation, and mean stigma-anther separation is predicted to decrease as a correlated response, increasing the fraction of plants that engage in prior selfing. However, the initial response to this selection is opposed by strong directional dominance. The predicted evolutionary decrease in the number of CH flowers available for potential outcrossing, combined with the apparent preclusion of potential diurnal pollinators by the pollen-harvesting activities of sweat bees, suggest that 100% cleistogamy is the likely outcome of evolution in the absence of hawkmoths. However, rare mutations with large effects, such as delaying budbreak until after sunrise, could provide pathways for the restoration of outcrossing that are not reachable by gradual quantitative-genetic evolution.

Living in an urban pod: Seed predation and parasitism of bruchid beetles in a native tree species

Abstract Urbanisation is one of the main drivers of insect species loss worldwide. However, its impacts on ecological interactions involving insects still deserve further research, especially seed predation and parasitism of seed predators. Here, we evaluated the seed predation rate by the specialist bruchid beetle Pseudopachymerina spinipes and its parasitism rate in the native tree Vachellia caven (Fabaceae) along an urbanisation gradient in Cordoba (Argentina). Since resource availability can influence these ecological interactions, we also investigated whether seed and prey availability could affect seed predation and parasitism rates, respectively. We sampled trees in 10 sampling sites along an urbanisation gradient estimated by the Normalised Difference Vegetation Index (NDVI) within a 100 m radius. In our system, sites with low NDVI, beyond representing the low amount of vegetation cover, also indicate high surface temperature and low availability of host trees. Seed predation in V. caven and the parasitism rate of P. spinipes were significantly reduced with increasing urbanisation. Notably, seed availability at the pod level did not affect seed predation rate, while prey availability was negatively correlated with parasitism rate. These findings suggest a deleterious effect of urbanisation on the studied antagonistic interactions, giving no support to the idea of resource limitation effects.

Land-cover change and effects at the local scale on pre-dispersal seed predation by Pachymerus nucleorum (Bruchinae) in the tropical palm Syagrus coronata (Arecaceae)

Seed predation is a major seed event in palms and affects seedling recruitment and the economic value of fruits. We investigated variations in the vegetative and reproductive traits, demography, habitat structure (tree richness), and pre-dispersal seed predation in the palm Syagrus coronata (Martius) Beccari (Arecaceae) by Pachymerus nucleorum (Fabricius) (Bruchinae) in habitats with different management intensities in the Brazilian semiarid region. In addition, we also assessed whether these plant variables affect seed predation. The palm tree known as licuri is widely used in extractivism and its cutting is prohibited by the Brazilian law. It is common to find isolated individuals in landscapes managed for agriculture and pasture. We predicted that more homogeneous microhabitats (with lower diversity of woody plants and higher density of licuri) with little fruiting synchrony would have higher levels of seed predation. Moreover, at the plant level, licuri individuals whose bunch are taller from the ground and with a larger number of fruits would sustain a lower proportion of pre-dispersal seed predation. The study was carried out in 13 sites, distributed between managed (pasture) and natural (Caatinga vegetation) habitats. Overall, 3,120 fruits were assessed, out of which 25.6% were preyed by P. nucleorum. We found that habitats with natural vegetation supported a higher density of adult licuri individuals and richness of woody plants, lower licuri fruiting synchrony, and greater seed predation. In addition, seed predation was positively affected by both total licuri abundance and tree richness, and negatively by the abundance of licuri fruiting at a micro-habitat level. This palm has unseasonal fruiting throughout all months of the year, and we suggested that the fruit harvest could be concentrated in the months of fruiting peak and the managed areas. Such measures could result in the harvest of healthier fruits by extractive populations and in seeds free from predation for use in habitat restoration through direct seeding.

Abundance, microhabitat and feeding of Peromyscus yucatanicus and Peromyscus mexicanus in the Mexican tropics

Introduction: Rodents influence the processes of succession and regeneration in tropical forests, functioning as important dispersers and predators of seeds and plants. In this study, we describe aspects of the population structure and dynamics, and characterize the microhabitat and composition of the feces of the semi-tree-dwelling rodents Peromyscus yucatanicusand Peromyscus mexicanus in tropical forests of Quintana Roo and Veracruz, in Mexico. Methods: We trapped Peromyscus yucatanicus from September 2014 to February 2015, with 122 Sherman traps between 2 to 10 m of height in 62 trees. Peromyscus mexicanus was trapped from March to September of 2015, with 105 Sherman traps between 0-11 m of height on 57 trees. We characterized the microhabitat, identified the trees, and calculated the canopy openness in the sites where individuals were trapped. We collected and analyzed the composition of the feces of each species. Results: We captured 48 individuals of Peromyscus yucatanicus at an average height of 2.58 m above ground level. Its population density was 26.6 ind/ha, with reproductive activity in the dry season. The average canopy openness was 7.75 %. Their feces mainly contained seeds, fruit pulp and starch. We recorded 54 individuals of Peromyscus mexicanus at an average height of 1.15 m. Its population density was 20.83 ind/ha, with reproductive activity in both dry and rainy seasons. The canopy openness was 4.78 % (dry season) and 4.5 % (rainy season). Their feces mainly contained fruit pulp, starch and chitin remains in both seasons. Discussion and conclusions: The captured of rodents were higher on trees with small diameters and low leaf litter percentage; the rainy season favored the captures. Both species were mainly captured in sites with a covering of organic matter on the soil and in sites with higher vegetal cover and reduced canopy openness. Conservation of a diverse tropical forest is fundamental for the conservation of both semiarboreal rodents.

Relationships between Soil Tillage Systems, Nematode Communities and Weed Seed Predation

Soil tillage is generally recognized as having a negative effect on soil health and weed seed predators. Recent advancements in conservation tillage practices allow for further comparison of how different levels of soil disturbances could influence soil food web communities. Field trials were conducted in 2017 and 2018 at two different sites to measure the effects of four cover crop termination treatments: conventional till (CT), no-till (NT), strip-till following roller-crimping (ST-RC), and strip-till with a living mulch between crop rows (ST-LM) on soil health using nematode community indices as soil health bioindicators. Following cover crop termination, the soil was monitored in the subsequent bell pepper (Capsicum annuum) crop over three sampling dates (June, August, and October). In the ST-RC treatment plots, soil nutrients were enriched (increased Enrichment Index, EI) and the soil food web structure was improved (higher Structure Index, SI) by the mid-season of the 2017 trial. In the 2018 trial, the ST-RC treatment enhanced fungal decomposition pathways (fungivore/fungivore + bacterivore ratio) throughout the bell pepper crop cycle and enhanced bacterial decomposition (abundance of bacterivorous nematodes) by the end of the cropping cycle compared to the no-till treatment, suggesting that the ST-RC treatment can further improve soil health conditions achieved by the NT treatment. Scatter plots of sampling points revealed that the treatments CT and NT had very distinct nematode-weed community assemblages in both trials, with the ST-RC and ST-LM treatments distributed closely with the NT treatment. Multivariate analysis among soil health bioindicators, weed pressure and weed seed predation explained 76.4 and 55.7% of the variance in the 2017 and 2018 trials, respectively. Weed pressure was consistently negatively related to (1) the SI, indicating soil disturbance would lead to more weed pressure; (2) the EI, indicating soil with higher weed pressure was linked to poor soil nutrient cycling, (3) cover crop residues left in the field from conservation tillage, or (4) how well the living mulch of red clover covered the ground. This study did not show that weed seed predation would lead to lower weed pressure but weed seed predation increased as weed biomass increased.

Are the Interactions between Oaks and Pre-Dispersal Seed Predators Retained in Urban Environments? An Analysis of Two Quercus Species in Southern Mexico City

As urbanization proceeds, natural ecosystems surrounding cities are transformed, but usually some elements persist, notably trees from forest ecosystems. However, it is still unknown the extent to which isolated trees, immersed in an urban matrix, maintain their interactions with insects that feed on their seeds. In this work we analyzed pre-dispersal seed predation by the two main groups of insects, weevils (Coleoptera; Curculionidae) and moths (Lepidoptera: Tortricidae), whose larvae feed on the acorns of two oak species (Quercus rugosa and Q. castanea). We compared these interactions between trees located in a protected forested area and trees isolated in an urban matrix. Our hypothesis was that, since pre-dispersal seed predation depends on insect dispersal, acorns from isolated trees would have lower predation levels than acorns from trees in the forest. A second hypothesis, based on reports that moths exhibit larger dispersal distances than weevils, was that isolated trees would have higher predation levels from moths than from weevils compared to their respective proportions in forest trees. Finally, we expected that moth predation would increase with seed size, as it does in weevils. We collected 1200 acorns of the two oak species (ten trees per species) in a protected oak forest and a nearby highway in southern Mexico City. From the whole sample, 17.3% of the acorns were predated by weevils and 3.8% by moths. The probability of predation was larger in acorns from trees in the forest (0.30) than in those from isolated trees (0.07), which confirmed the first hypothesis; tree species identity did not have a significant effect on the proportion of predated acorns. When only predated acorns were analyzed, predation by weevil larvae was larger than predation by moths in both oak species, although the probability of predation by weevils was higher in the oak species having large acorns (Q. rugosa, 0.93), than in the species with small acorns (Q. castanea, 0.63). Inversely, predation by moths was higher in Q. castanea (0.37) than in Q. rugosa (0.07). Seed predation decreased similarly for weevils and moths in isolated trees, so we failed to find support for our second hypothesis. A positive relationship between seed predation by weevils and seed size was found in Q. rugosa but not in Q. castanea; seed size did not affect predation by moth larvae. Therefore, although isolated trees in the urban matrix harbor smaller populations of pre-dispersal seed predators than forest trees, their interactions with the two main groups of insects feeding on acorns are maintained, which points to their importance for the conservation of urban biodiversity.

The functional form of specialised predation affects whether Janzen–Connell effects can prevent competitive exclusion

Janzen–Connell effects (JCEs), specialised predation of seeds and seedlings near conspecific trees, are hypothesised to maintain species richness. While previous studies show JCEs can maintain high richness relative to neutral communities, recent theoretical work indicates JCEs may weakly inhibit competitive exclusion when species exhibit interspecific fitness variation. However, recent models make somewhat restrictive assumptions about the functional form of specialised predation—that JCEs occur at a fixed rate when offspring are within a fixed distance of a conspecific tree. Using a theoretical model, I show that the functional form of JCEs largely impacts their ability to maintain coexistence. If predation pressure increases additively with adult tree density and decays exponentially with distance, JCEs maintain considerably higher species richness than predicted by recent models. Loosely parameterising the model with data from a Panamanian tree community, I elucidate the conditions under which JCEs are capable of maintaining high species richness.

Selection of Floral Traits by Pollinators and Seed Predators during Sequential Life History Stages.

AbstractOrganismal traits often influence fitness via interactions with multiple species. That selection is not necessarily predictable from pairwise interactions, such as when interactions occur during different life cycle stages. Theoretically, directional selection during two sequential episodes (e.g., pollination and seed survival) can generate quadratic or correlational selection for a set of traits that passes both selective filters. We compared strength of selection during pollination versus seed predation in the field and tested whether interactions with multiple species give rise to nonlinear selection on floral traits. We planted common gardens with seeds of two species of Ipomopsis and hybrids at sites where pollination was primarily by hummingbirds or also included hawk moths. We examined selection on six floral traits, including corolla width, sepal width, color, nectar, and two scent compounds. Female fitness (seeds) was broken down into fitness during (1) pollination (seeds initiated) and (2) seed predation (proportion of seeds escaping fly predation). All traits showed evidence of selection. Directional and quadratic selection were stronger during seed initiation than during seed predation. Correlational selection occurred mostly during seed initiation rather than arising from combining species interactions at two points in the life cycle. These results underscore how multispecies interactions can combine to exert selection on trait combinations.

Natural enemies emerging in cereal fields in spring may contribute to biological control

Abstract Biological pest control is known to depend on landscape heterogeneity. However, such relationship shows irregular pattern and seems influenced by local farming practices and natural enemies that overwinter within crop fields. The objective of this study was to assess the contribution of emerging natural enemies in spring to biological control, and their response to the interaction between landscape heterogeneity and farming intensity. We monitored the overwintering insect community using emergence traps and measured the local potential pest predation using prey cards in 30 cereal fields, in spring in France. Study fields were selected along a landscape heterogeneity gradient and farming practices were recorded. None of the 10 emerging taxa influenced predation of lepidopteran eggs or weed seeds. On the ground, aphid predation was positively correlated with emerging carabid beetles. On foliage, aphid predation was negatively correlated with emerging parasitoids. Overall, the community of natural enemies that overwinters within crop fields seemed to benefit from landscape‐scale lower crop diversity and higher edge density in combination with higher local‐scale farming intensities. This suggests that they represent a subset of species adapted to intensified farming systems. This study highlights a broad taxonomic range of emerging natural enemies and their potential contribution to local pest predation.