11Bees are subject to numerous pressures in the modern world. The abundance and diversity of 12 flowers has declined, bees are chronically exposed to cocktails of agrochemicals, and they are 13 simultaneously exposed to novel parasites accidentally spread by humans. Climate change is 14 likely to exacerbate these problems in the future. Stressors do not act in isolation; for example 15 pesticide exposure can impair both detoxification mechanisms and immune responses, 16 rendering bees more susceptible to parasites. It seems certain that chronic exposure to 17 multiple, interacting stressors is driving honey bee colony losses and declines of wild 18pollinators, but such interactions are not addressed by current regulatory procedures and 19 studying these interactions experimentally poses a major challenge. In the meantime, taking 20 steps to reduce stress on bees would seem prudent; incorporating flower-rich habitat into 21 farmland, reducing pesticide use through adopting more sustainable farming methods, and 22

In recent years, an intense debate about the environmental risks posed by neonicotinoids, a group of widely used, neurotoxic insecticides, has been joined. When these systemic compounds are applied to seeds, low concentrations are subsequently found in the nectar and pollen of the crop, which are then collected and consumed by bees. Here we demonstrate that the current focus on exposure to pesticides via the crop overlooks an important factor: throughout spring and summer, mixtures of neonicotinoids are also found in the pollen and nectar of wildflowers growing in arable field margins, at concentrations that are sometimes even higher than those found in the crop. Indeed, the large majority (97%) of neonicotinoids brought back in pollen to honey bee hives in arable landscapes was from wildflowers, not crops. Both previous and ongoing field studies have been based on the premise that exposure to neonicotinoids would occur only during the blooming period of flowering crops and that it may be diluted by bees also foraging on untreated wildflowers. Here, we show that exposure is likely to be higher and more prolonged than currently recognized because of widespread contamination of wild plants growing near treated crops.

(2016) Widespread contamination of wildflower and beecollected pollen with complex mixtures of neonicotinoids and fungicides commonly applied to crops. Environment International, This version is available from Sussex Research Online: http://sro.sussex.ac.uk/59217/ This document is made available in accordance with publisher policies and may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the URL above for details on accessing the published version. Copyright and reuse:Sussex Research Online is a digital repository of the research output of the University.Copyright and all moral rights to the version of the paper presented here belong to the individual author(s) and/or other copyright owners. To the extent reasonable and practicable, the material made available in SRO has been checked for eligibility before being made available.Copies of full text items generally can be reproduced, displayed or performed and given to third parties in any format or medium for personal research or study, educational, or not-for-profit purposes without prior permission or charge, provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. Widespread contamination of wildflower and bee-collected pollen1 with complex mixtures of neonicotinoids and fungicides. There is considerable and ongoing debate as to the harm inflicted on bees by exposure to 16 agricultural pesticides. In part, the lack of consensus reflects a shortage of information on field-17 realistic levels of exposure. Here, we quantify concentrations of neonicotinoid insecticides and 18 fungicides in the pollen of oilseed rape, and in pollen of wildflowers growing near arable fields. We 19 then compare this to concentrations of these pesticides found in pollen collected by honey bees and 20 in pollen and adult bees sampled from bumblebee colonies placed on arable farms. We also 21 compared this with levels found in bumblebee colonies placed in urban areas. Pollen of oilseed rape 22 was heavily contaminated with a broad range of pesticides, as was the pollen of wildflowers growing 23 nearby. Consequently, pollen collected by both bee species also contained a wide range of 24 pesticides, notably including the fungicides carbendazim, boscalid, flusilazole, metconazole, 25 tebuconazole and trifloxystrobin and the neonicotinoids thiamethoxam, thiacloprid and 26 imidacloprid. In bumblebees, fungicides carbendazim, boscalid, tebuconazole, flusilazole and 27 metconazole were present at concentrations up to 73 nanogram/gram (ng/g). Pesticide 28 concentrations in pollen collected by honeybees tended to be lower than those in pollen collected 29 by bumblebees. It is notable that pollen collected by bumblebees in rural areas contained high levels 30 of the neonicotinoids thiamethoxam (mean 18 ng/g) and thiacloprid (mean 2.9 ng/g), along with a 31 range ...

Summary1. The removal of pollen by flower-visiting insects is costly to plants, not only in terms of production, but also via lost reproductive potential. Modern angiosperms have evolved various reward strategies to limit these costs, yet many plant species still offer pollen as a sole or major reward for pollinating insects. 2. The benefits plants gain by offering pollen as a reward for pollinating are defined by the behaviour of their pollinators, some of which feed on the pollen at the flower, while others collect pollen to provision offspring. 3. We explore how pollen impacts on the behaviour and foraging decisions of pollen-collecting bees, drawing comparisons with what is known for nectar rewards. This question is of particular interest since foraging bees typically do not eat pollen during collection, meaning the sensory pathways involved in evaluating this resource are not immediately obvious. 4. Previous research has focussed on whether foraging bees can determine the quality of pollen sources offered by different plant species, and attempted to infer the mechanisms underpinning such evaluations, mainly through observations of collection preferences in the field 5. More recently experimental research has started to ask whether pollen itself can mediate the detection of, and learning about, pollen sources and associated floral cues. 6. We review advancements in the understanding of how bees forage for pollen and respond to variation in pollen quality, and discuss future directions for studying how this ancestral floral food reward shapes the behaviour of pollinating insects.

Food production depends upon the adequate provision of underpinning ecosystem services, such as pollination. Paradoxically, conventional farming practices are undermining these services and resulting in degraded soils, polluted waters, greenhouse gas emissions and massive loss of biodiversity including declines in pollinators. In essence, farming is undermining the ecosystem services it relies upon. Finding alternative more sustainable ways to meet growing food demands which simultaneously support biodiversity is one of the biggest challenges facing humanity. Here, we review the potential of urban and peri-urban agriculture to contribute to sustainable food production, using the 17 sustainable development goals set by the United Nations General Assembly as a framework. We present new data from a case study of urban gardens and allotments in the city of Brighton and Hove, UK. Such urban and peri-urban landholdings tend to be small and labour-intensive, characterised by a high diversity of crops including perennials and annuals. Our data demonstrate that this type of agricultural system can be highly productive and that it has environmental and social advantages over industrial agriculture in that crops are usually produced using few synthetic inputs and are destined for local consumption. Overall, we conclude that food grown on small-scale areas in and near cities is making a significant contribution to feeding the world and that this type of agriculture is likely to be relatively favourable for some ecosystem services, such as supporting healthy soils. However, major knowledge gaps remain, for example with regard to productivity, economic and employment impacts, pesticide use and the implications for biodiversity.Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.