Increasing crop heterogeneity enhances multitrophic diversity across agricultural regions

International audienceAgricultural landscape homogenization has detrimental effects on biodiversity and key ecosystem services. Increasing agricultural landscape heterogeneity by increasing seminatural cover can help to mitigate biodiversity loss. However, the amount of seminatural cover is generally low and difficult to increase in many intensively managed agricultural landscapes. We hypothesized that increasing the heterogeneity of the crop mosaic itself (hereafter “crop heterogeneity”) can also have positive effects on biodiversity. In 8 contrasting regions of Europe and North America, we selected 435 landscapes along independent gradients of crop diversity and mean field size. Within each landscape, we selected 3 sampling sites in 1, 2, or 3 crop types. We sampled 7 taxa (plants, bees, butterflies, hoverflies, carabids, spiders, and birds) and calculated a synthetic index of multitrophic diversity at the landscape level. Increasing crop heterogeneity was more beneficial for multitrophic diversity than increasing seminatural cover. For instance, the effect of decreasing mean field size from 5 to 2.8 ha was as strong as the effect of increasing seminatural cover from 0.5 to 11%. Decreasing mean field size benefited multitrophic diversity even in the absence of seminatural vegetation between fields. Increasing the number of crop types sampled had a positive effect on landscape-level multitrophic diversity. However, the effect of increasing crop diversity in the landscape surrounding fields sampled depended on the amount of seminatural cover. Our study provides large-scale, multitrophic, cross-regional evidence that increasing crop heterogeneity can be an effective way to increase biodiversity in agricultural landscapes without taking land out of agricultural production

New genetic loci link adipose and insulin biology to body fat distribution.

Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes, independent of overall adiposity. To increase our understanding of the genetic basis of body fat distribution and its molecular links to cardiometabolic traits, here we conduct genome-wide association meta-analyses of traits related to waist and hip circumferences in up to 224,459 individuals. We identify 49 loci (33 new) associated with waist-to-hip ratio adjusted for body mass index (BMI), and an additional 19 loci newly associated with related waist and hip circumference measures (P < 5 × 10(-8)). In total, 20 of the 49 waist-to-hip ratio adjusted for BMI loci show significant sexual dimorphism, 19 of which display a stronger effect in women. The identified loci were enriched for genes expressed in adipose tissue and for putative regulatory elements in adipocytes. Pathway analyses implicated adipogenesis, angiogenesis, transcriptional regulation and insulin resistance as processes affecting fat distribution, providing insight into potential pathophysiological mechanisms

Data from: Maize-dominated landscapes reduce bumble bee colony growth through pollen diversity loss

1. Bumble bees are important pollinators for a wide range of crops and wild plants. Performance of their colonies depends on pollen and nectar as food resources, but flowering plants are scarce in modern agricultural landscapes. It is well-known that semi-natural habitats can enhance floral resources and bumble bee abundance, but the impact of different crop types and their heterogeneity at the landscape scale remains unclear. 2. We tested the effect of two different crop types (oilseed rape (OSR) and maize) and of configurational (field border density) and compositional heterogeneity (crop diversity) on weight gain of buff-tailed bumble bee colonies (Bombus terrestris) colonies and the pollen diversity collected by them in 20 landscapes in Central Germany. 3. We found that augmenting maize cover had a detrimental effect on pollen diversity collected by the bumble bees, probably due to intensive management resulting in low plant diversity. This low pollen diversity translated into reduced colony growth, since colonies with high pollen diversity gained more weight than colonies with low pollen diversity. 4. In contrast, OSR cover, configurational and compositional heterogeneity did neither affect colony growth nor pollen diversity. However, for OSR the timing of the flowering period was important. When OSR fields had a high flower cover at the end of the OSR blooming period, colonies showed increased growth rates. 5. Synthesis and applications. Our results complement previous laboratory studies by showing that high pollen diversity leads to better colony performance under field conditions. Therefore, the maintenance of floral diversity in agricultural landscapes is crucial to ensure that bumble bees can fulfil their nutritional needs. However, the heterogeneity of crops, at least under the currently very low levels of crop rotation, does not contribute to this aim. In contrast, crop identity and timing of mass-flowering crops turned out to be important factors, as maize reduced pollen resources, while late blooming OSR oilseed rape was beneficial for bumble bee colonies. Hence, maize cover per landscape should be reduced and strategies to enhance landscape wide flower diversity, especially towards and after the end of oilseed rape bloom should be promoted to support bumble bee colonies that provide important pollination services

Data from: Maize-dominated landscapes reduce bumble bee colony growth through pollen diversity loss

1. Bumble bees are important pollinators for a wide range of crops and wild plants. Performance of their colonies depends on pollen and nectar as food resources, but flowering plants are scarce in modern agricultural landscapes. It is well-known that semi-natural habitats can enhance floral resources and bumble bee abundance, but the impact of different crop types and their heterogeneity at the landscape scale remains unclear. 2. We tested the effect of two different crop types (oilseed rape (OSR) and maize) and of configurational (field border density) and compositional heterogeneity (crop diversity) on weight gain of buff-tailed bumble bee colonies (Bombus terrestris) colonies and the pollen diversity collected by them in 20 landscapes in Central Germany. 3. We found that augmenting maize cover had a detrimental effect on pollen diversity collected by the bumble bees, probably due to intensive management resulting in low plant diversity. This low pollen diversity translated into reduced colony growth, since colonies with high pollen diversity gained more weight than colonies with low pollen diversity. 4. In contrast, OSR cover, configurational and compositional heterogeneity did neither affect colony growth nor pollen diversity. However, for OSR the timing of the flowering period was important. When OSR fields had a high flower cover at the end of the OSR blooming period, colonies showed increased growth rates. 5. Synthesis and applications. Our results complement previous laboratory studies by showing that high pollen diversity leads to better colony performance under field conditions. Therefore, the maintenance of floral diversity in agricultural landscapes is crucial to ensure that bumble bees can fulfil their nutritional needs. However, the heterogeneity of crops, at least under the currently very low levels of crop rotation, does not contribute to this aim. In contrast, crop identity and timing of mass-flowering crops turned out to be important factors, as maize reduced pollen resources, while late blooming OSR oilseed rape was beneficial for bumble bee colonies. Hence, maize cover per landscape should be reduced and strategies to enhance landscape wide flower diversity, especially towards and after the end of oilseed rape bloom should be promoted to support bumble bee colonies that provide important pollination services

Maize-dominated landscapes reduce bumblebee colony growth through pollen diversity loss

Bumblebees are important pollinators for a wide range of crops and wild plants. Performance of their colonies depends on pollen and nectar as food resources, but flowering plants are scarce in modern agricultural landscapes. It is well-known that semi-natural habitats can enhance floral resources and bumblebee abundance, but the impact of different crop types and their heterogeneity at the landscape scale remains unclear. We tested the effect of two different crop types (oilseed rape [OSR] and maize) and of configurational (field border density) and compositional heterogeneity (crop diversity) on weight gain of buff-tailed bumblebee colonies (Bombus terrestris) and the pollen diversity collected by them in 20 landscapes in Central Germany. We found that augmenting maize cover had a detrimental effect on pollen diversity collected by bumblebees, probably due to intensive management resulting in low plant diversity. This low pollen diversity translated into reduced colony growth, since colonies with high pollen diversity gained more weight than colonies with low pollen diversity. In contrast, OSR cover and configurational and compositional heterogeneity did neither affect colony growth nor pollen diversity. However, for OSR, the timing of the flowering period was important. When OSR fields had a high flower cover at the end of the OSR blooming period, colonies showed increased growth rates. Synthesis and applications. Our results complement previous laboratory studies by showing that high pollen diversity leads to better colony performance under field conditions. Therefore, the maintenance of floral diversity in agricultural landscapes is crucial to ensure that bumblebees can fulfil their nutritional needs. However, the heterogeneity of crops, at least under the currently very low levels of crop rotation, does not contribute to this aim. In contrast, crop identity and timing of mass-flowering crops turned out to be important factors, as maize reduced pollen resources, while late blooming oilseed rape (OSR) was beneficial to bumblebee colonies. Hence, maize cover per landscape should be reduced and strategies to enhance landscape wide flower diversity, especially towards and after the end of oilseed rape bloom, should be promoted to support bumblebee colonies that provide important pollination services

Plant-pollinator interactions and bee functional diversity are driven by agroforests in rice-dominated landscapes

Wild and domestic bees are essential for the pollination of crops in home gardens, agroforests and vegetable fields of rice smallholders. However, it remains unclear how rice fields and agroforests affect pollinator communities. We investigated the effects of habitat loss and isolation on four different components of bee diversity: abundance, species richness, functional diversity, and plant-pollinator interactions. Flower-visiting bees were recorded in a lowland rice-based production region on the Philippines. We sampled two different land use systems (agroforests and rice fields) and along a gradient of habitat isolation (isolated rice fields and rice fields connected to agroforests). All components of bee diversity were higher in agroforests than in rice fields. Especially above-ground nesting and long-tongued species were adversely affected by rice field habitats and body sizes decreased with isolation from agroforests. For plant-pollinator interactions we found that plants received less diverse pollinator visits in isolated rice fields. In conclusion, agroforests provide important food and nesting resources for bees that translate into taxonomically and functionally diverse pollinator communities as well as stable pollinator visitation networks. These cultivation systems should therefore be maintained or expanded to ensure pollination services and biodiversity conservation. On the contrary, rice fields provide habitat for only few generalist bee species and flower visitation is reduced in isolated rice fields, possibly also leading to impaired pollination of wild plants and crops. Connectivity between bee habitats located in rice production areas is probably disrupted even after a few hundred meters and should therefore be promoted by measures like flower strips in rice fields