Breno Magalhães Freitas

Non-bee insects are important contributors to global crop pollination

Significance Many of the world’s crops are pollinated by insects, and bees are often assumed to be the most important pollinators. To our knowledge, our study is the first quantitative evaluation of the relative contribution of non-bee pollinators to global pollinator-dependent crops. Across 39 studies we show that insects other than bees are efficient pollinators providing 39% of visits to crop flowers. A shift in perspective from a bee-only focus is needed for assessments of crop pollinator biodiversity and the economic value of pollination. These studies should also consider the services provided by other types of insects, such as flies, wasps, beetles, and butterflies—important pollinators that are currently overlooked. Wild and managed bees are well documented as effective pollinators of global crops of economic importance. However, the contributions by pollinators other than bees have been little explored despite their potential to contribute to crop production and stability in the face of environmental change. Non-bee pollinators include flies, beetles, moths, butterflies, wasps, ants, birds, and bats, among others. Here we focus on non-bee insects and synthesize 39 field studies from five continents that directly measured the crop pollination services provided by non-bees, honey bees, and other bees to compare the relative contributions of these taxa. Non-bees performed 25–50% of the total number of flower visits. Although non-bees were less effective pollinators than bees per flower visit, they made more visits; thus these two factors compensated for each other, resulting in pollination services rendered by non-bees that were similar to those provided by bees. In the subset of studies that measured fruit set, fruit set increased with non-bee insect visits independently of bee visitation rates, indicating that non-bee insects provide a unique benefit that is not provided by bees. We also show that non-bee insects are not as reliant as bees on the presence of remnant natural or seminatural habitat in the surrounding landscape. These results strongly suggest that non-bee insect pollinators play a significant role in global crop production and respond differently than bees to landscape structure, probably making their crop pollination services more robust to changes in land use. Non-bee insects provide a valuable service and provide potential insurance against bee population declines.

Diversity, threats and conservation of native bees in the Neotropics

The Neotropics bee fauna is very rich with 5000 recognised species, including 33 genera (391 species) of Meliponini, but it is estimated to be at least three fold greater in species richness. Deforestation, agriculture intensification and introduction/spread of exotic competing bee species are considered the main threats to most indigenous species, although other less obvious causes can affect the populations of some bee species locally. Efforts to conserve the native bee fauna include better knowledge of bee richness and diversity (standardized surveys, larger bee collections and appropriate identification of bee species) and of their population dynamics, raising of public and policy makers’ awareness, commercial applications of bee products and services such as pollination and preservation of natural habitat.ZusammenfassungDie vorliegende Arbeit soll einen Überblick geben über die Diversität und den Artenreichtum der neotropischen Bienenfauna, die Bedrohungen, denen sie ausgesetzt ist, als auch eine Darstellung der Initiativen und Probleme im Artenschutz der einheimischen Bienen. Die Daten beruhen auf umfassenden Literaturrecherchen. Diese Informationen wurden dann von den Autoren diskutiert und in Form relevanter Punkte inhaltlich zusammengefasst. Das Ergebnis zeigt, dass die Neotropis eine artenreiche Bienenfauna aufweist und dass diese sogar unterschätzt wird. Den existierenden 5000 gültigen Artennamen stehen Schätzungen gegenüber, dass diese weniger als ein Drittel der tatsächlich vorkommenden Arten umfassen (Tab. I). Bedrohungen, denen einheimische Bienen der Neotropis ausgesetzt sind, liegen vor allem menschliche Aktivitäten zugrunde, die in drei Kategorien zusammengefasst werden können: Entwaldung, Intensivierung der Landwirtschaft und Einführung fremder Arten. Die Hauptursachen der Entwaldung sind Holzeinschlag, das Sammeln von Feuerholz, die Produktion von Holzkohle und Rodungen zur Schaffung von landwirtschaftlichen und Weideflächen. Der Amazonasregenwald, Mexiko und Zentralamerika weisen die höchsten Entwaldungsraten in Amerika auf, aber auch in den Chaco-Wälder der argentinischen und kolumbianischen Anden schreitet die Entwaldung fort (Tab. II). Die Ausbreitung und Intensivierung der Landwirtschaft wird vielfach als die wichtigste Bedrohung für Bienenarten angesehen. Sie führt zu einer Verringerung der Artendiversität bei Tieren und Pflanzen, verringert das Angebot an Nistmöglichkeiten und Futterquellen, und durch das Ausbringen von Pestiziden und Pflügen der Böden werden sowohl Bienenlarven als auch Adulte getötet. Ironischerweise sind die meisten Kulturpflanzen mehr oder weniger stark auf die Präsenz biotischer Bestäuber angewiesen, wobei die Bienen die wichtigste Gruppe darstellen. Auch die Einführung fremder Bienenarten und anderer exotischer Organismen, die mit der lokalen Bienenfauna in Wechselwirkung treten, kann die einheimische Bienenfauna beeinträchtigen. Die Einführung von Apis mellifera in die Neue Welt zur Steigerung der Honigproduktion und die von exotischen Hummelarten für Bestäubungszwecke hat zu Bedenken Anlass gegeben über die Konkurrenz mit einheimischen Bienen um Futter- und Nistmöglichkeiten, sowie zur Ausbreitung von Krankheiten und Parasiten und zur Hybridisierung mit einheimischen Hummmelarten. Anderen Bedrohungen liegen Trockenzeiten, Überschwemmungen, grossflächige Buschbrände, Hurrikane und die Kontaminierung der Ökosysteme mit Schwermetallen zugrunde. Die Hauptprobleme, denen sich Initiativen zum Artenschutz einheimischer Bienen gegenübersehen, sind fehlende Kenntnisse über Artenreichtum, Diversität, Taxonomie, Populationsdynamik und den Einfluss menschlicher Aktivitäten auf die meisten Bienenarten. Um zu besseren Kenntnissen über Artenreichtum, Diversität und Populationsdynamik zu kommen, ist Öffentlichkeitsarbeit und Aufklärung bei Politikverantwortlichen erforderlich. Hierin können die Kommerzialisierung von Bienenprodukten, sowie Aufklärung über die Bedeutung von Bestäubern und der Schutz natürlicher Habitate eine wichtige Rolle spielen. Bestäuberinitiativen erweisen sich hierbei als wichtige Werkzeuge, um Politiker, die Öffenlichkeit und Forscher in koordinierter Weise zusammenzubringen, Wissen über wichtige Fragen zu schaffen und insbesondere die negativen Auswirkungen bienenbedrohender Aktivitäten in Lateinamerika abzumildern.

Mutually beneficial pollinator diversity and crop yield outcomes in small and large farms

More-diverse pollinators improve crop yields It is known that increased pollinator diversity can improve the yield of agricultural crops. However, how best to both produce food and maintain diversity is still debated. Garibaldi et al. show that on small farms, which provide food for the most vulnerable populations globally, pollinator diversity can significantly increase productivity. Thus, the management of crops and surrounding areas for ecological health is likely to benefit both wild pollinator populations and farmers. Science, this issue p. 388 A large international data set confirms that increased diversity of wild pollinators increases crop yields. Ecological intensification, or the improvement of crop yield through enhancement of biodiversity, may be a sustainable pathway toward greater food supplies. Such sustainable increases may be especially important for the 2 billion people reliant on small farms, many of which are undernourished, yet we know little about the efficacy of this approach. Using a coordinated protocol across regions and crops, we quantify to what degree enhancing pollinator density and richness can improve yields on 344 fields from 33 pollinator-dependent crop systems in small and large farms from Africa, Asia, and Latin America. For fields less than 2 hectares, we found that yield gaps could be closed by a median of 24% through higher flower-visitor density. For larger fields, such benefits only occurred at high flower-visitor richness. Worldwide, our study demonstrates that ecological intensification can create synchronous biodiversity and yield outcomes.

Standard methods for pollination research with Apis mellifera

Summary In this chapter we present a synthesis of recommendations for conducting field experiments with honey bees in the context of agricultural pollination. We begin with an overview of methods for determining the mating system requirements of plants and the efficacy of specific pollinators. We describe methods for evaluating the pollen-vectoring capacity of bees at the level of individuals or colonies and follow with methods for determining optimum colony field stocking densities. We include sections for determining post-harvest effects of pollination, the effects of colony management (including glasshouse enclosure) on bee pollination performance, and a brief section on considerations about pesticides and their impact on pollinator performance. A final section gives guidance on determining the economic valuation of honey bee colony inputs at the scale of the farm or region.

Trait matching of flower visitors and crops predicts fruit set better than trait diversity

Understanding the relationships between trait diversity, species diversity and ecosystem functioning is essential for sustainable management. For functions comprising two trophic levels, trait matching between interacting partners should also drive functioning. However, the predictive ability of trait diversity and matching is unclear for most functions, particularly for crop pollination, where interacting partners did not necessarily co-evolve. World-wide, we collected data on traits of flower visitors and crops, visitation rates to crop flowers per insect species and fruit set in 469 fields of 33 crop systems. Through hierarchical mixed-effects models, we tested whether flower visitor trait diversity and/or trait matching between flower visitors and crops improve the prediction of crop fruit set (functioning) beyond flower visitor species diversity and abundance. Flower visitor trait diversity was positively related to fruit set, but surprisingly did not explain more variation than flower visitor species diversity. The best prediction of fruit set was obtained by matching traits of flower visitors (body size and mouthpart length) and crops (nectar accessibility of flowers) in addition to flower visitor abundance, species richness and species evenness. Fruit set increased with species richness, and more so in assemblages with high evenness, indicating that additional species of flower visitors contribute more to crop pollination when species abundances are similar.Synthesis and applications. Despite contrasting floral traits for crops world-wide, only the abundance of a few pollinator species is commonly managed for greater yield. Our results suggest that the identification and enhancement of pollinator species with traits matching those of the focal crop, as well as the enhancement of pollinator richness and evenness, will increase crop yield beyond current practices. Furthermore, we show that field practitioners can predict and manage agroecosystems for pollination services based on knowledge of just a few traits that are known for a wide range of flower visitor species. Despite contrasting floral traits for crops world-wide, only the abundance of a few pollinator species is commonly managed for greater yield. Our results suggest that the identification and enhancement of pollinator species with traits matching those of the focal crop, as well as the enhancement of pollinator richness and evenness, will increase crop yield beyond current practices. Furthermore, we show that field practitioners can predict and manage agroecosystems for pollination services based on knowledge of just a few traits that are known for a wide range of flower visitor species. Editors Choice

Ninhos racionais para mamangava (Xylocopa frontalis) na polinização do maracujá-amarelo (Passiflora edulis)

Brazil is the largest producer of passionfruit (Passiflora edulis) in the world, but holds low fruit productivity due to the lack of natural pollinators such as carpenter bees (Xylocopa spp.) in cultivated areas. The present work investigated the use in passionfruit plantations of a model of rational nesting box for carpenter bees suggested by FREITAS & OLIVEIRA FILHO (2001). Results showed that the

Bees for development: Brazilian survey reveals how to optimize stingless beekeeping.

Stingless bees are an important asset to assure plant biodiversity in many natural ecosystems, and fulfill the growing agricultural demand for pollination. However, across developing countries stingless beekeeping remains an essentially informal activity, technical knowledge is scarce, and management practices lack standardization. Here we profited from the large diversity of stingless beekeepers found in Brazil to assess the impact of particular management practices on productivity and economic revenues from the commercialization of stingless bee products. Our study represents the first large-scale effort aiming at optimizing stingless beekeeping for honey/colony production based on quantitative data. Survey data from 251 beekeepers scattered across 20 Brazilian States revealed the influence of specific management practices and other confounding factors over productivity and income indicators. Specifically, our results highlight the importance of teaching beekeepers how to inspect and feed their colonies, how to multiply them and keep track of genetic lineages, how to harvest and preserve the honey, how to use vinegar traps to control infestation by parasitic flies, and how to add value by labeling honey containers. Furthermore, beekeeping experience and the network of known beekeepers were found to be key factors influencing productivity and income. Our work provides clear guidelines to optimize stingless beekeeping and help transform the activity into a powerful tool for sustainable development.

A horizon scan of future threats and opportunities for pollinators and pollination

Background. Pollinators, which provide the agriculturally and ecologically essential service of pollination, are under threat at a global scale. Habitat loss and homogenisation, pesticides, parasites and pathogens, invasive species, and climate change have been identified as past and current threats to pollinators. Actions to mitigate these threats, e.g., agri-environment schemes and pesticide-use moratoriums, exist, but have largely been applied post-hoc. However, future sustainability of pollinators and the service they provide requires anticipation of potential threats and opportunities before they occur, enabling timely implementation of policy and practice to prevent, rather than mitigate, further pollinator declines. Methods.Using a horizon scanning approach we identified issues that are likely to impact pollinators, either positively or negatively, over the coming three decades. Results.Our analysis highlights six high priority, and nine secondary issues. High priorities are: (1) corporate control of global agriculture, (2) novel systemic pesticides, (3) novel RNA viruses, (4) the development of new managed pollinators, (5) more frequent heatwaves and drought under climate change, and (6) the potential positive impact of reduced chemical use on pollinators in non-agricultural settings. Discussion. While current pollinator management approaches are largely driven by mitigating past impacts, we present opportunities for pre-emptive practice, legislation, and policy to sustainably manage pollinators for future generations.

Number and distribution of cashew (Anacardium occidentale) pollen grains on the bodies of its pollinators, Apis mellifera and Centris tarsata

SUMMARYThe number and distribution of cashew (Anacardium occidentale) pollen grains on the bodies of honey bees (Apis mellifera) and a solitary bee (Centris tarsata) were studied. There was a significant difference between the number of pollen grains found on the bodies of male and female C. tarsata and A. mellifera foragers. Female C tarsata carried twice as much pollen as A mellifera foragers. It is shown that cashew pollen was selectively distributed on a pollinators body and that it had little mobility on the bodies of the bees, tending to remain on the body parts upon which it was initially deposited. Areas of the body of the bee which had greater densities of cashew pollen had also touched cashew stigmas, supporting suggestions that A. mellifera and C. tarsata are effective cashew pollinators. It is suggested that for plant species with pollen deposition on and reception from localized areas of a floral visitor, displacement of their pollen over the entire visitors body reduces its efficiency as a...

A global synthesis of the effects of diversified farming systems on arthropod diversity within fields and across agricultural landscapes

Agricultural intensification is a leading cause of global biodiversity loss, which can reduce the provisioning of ecosystem services in managed ecosystems. Organic farming and plant diversification are farm management schemes that may mitigate potential ecological harm by increasing species richness and boosting related ecosystem services to agroecosystems. What remains unclear is the extent to which farm management schemes affect biodiversity components other than species richness, and whether impacts differ across spatial scales and landscape contexts. Using a global metadataset, we quantified the effects of organic farming and plant diversification on abundance, local diversity (communities within fields), and regional diversity (communities across fields) of arthropod pollinators, predators, herbivores, and detritivores. Both organic farming and higher in-field plant diversity enhanced arthropod abundance, particularly for rare taxa. This resulted in increased richness but decreased evenness. While these responses were stronger at local relative to regional scales, richness and abundance increased at both scales, and richness on farms embedded in complex relative to simple landscapes. Overall, both organic farming and in-field plant diversification exerted the strongest effects on pollinators and predators, suggesting these management schemes can facilitate ecosystem service providers without augmenting herbivore (pest) populations. Our results suggest that organic farming and plant diversification promote diverse arthropod metacommunities that may provide temporal and spatial stability of ecosystem service provisioning. Conserving diverse plant and arthropod communities in farming systems therefore requires sustainable practices that operate both within fields and across landscapes.