Infections caused by antibiotic resistant bacteria (ARB) are associated with poor health outcomes and are recognised globally as a serious health problem. Much research has been conducted on the ...transmission of ARB to humans. Yet the role the natural environment plays in the spread of ARB and antibiotic resistance genes is not well understood. Antibiotic resistant bacteria have been detected in natural aquatic environments, and ingestion of seawater during water sports is one route by which many people could be directly exposed.
The aim was to estimate the prevalence of resistance to one clinically important class of antibiotics (third-generation cephalosporins (3GCs)) amongst Escherichia coli in coastal surface waters in England and Wales. Prevalence data was used to quantify ingestion of 3GC-resistant E. coli (3GCREC) by people participating in water sports in designated coastal bathing waters. A further aim was to use this value to derive a population-level estimate of exposure to these bacteria during recreational use of coastal waters in 2012.
The prevalence of 3GC-resistance amongst E. coli isolated from coastal surface waters was estimated using culture-based methods. This was combined with the density of E. coli reported in designated coastal bathing waters along with estimations of the volumes of water ingested during various water sports reported in the literature to calculate the mean number of 3GCREC ingested during different water sports.
0.12% of E. coli isolated from surface waters were resistant to 3GCs. This value was used to estimate that in England and Wales over 6.3 million water sport sessions occurred in 2012 that resulted in the ingestion of at least one 3GCREC.
Despite the low prevalence of resistance to 3GCs amongst E. coli in surface waters, there is an identifiable human exposure risk for water users, which varies with the type of water sport undertaken. The relative importance of this exposure is likely to be greater in areas where a large proportion of the population enjoys water sports. Millions of water sport sessions occurred in 2012 that were likely to have resulted in people ingesting E. coli resistant to a single class of antibiotics (3GCs). However, this is expected to be a significant underestimate of recreational exposure to all ARB in seawater.
This is the first study to use volumes of water ingested during different water sports to estimate human exposure to ARB. Further work needs to be done to elucidate the health implications and clinical relevance of exposure to ARB in both marine and fresh waters in order to fully understand the risk to public health.
•3GC-resistant E. coli were detected in surface waters around England and Wales.•The mean prevalence of 3GC-resistance in E. coli in coastal waters is low.•There is an identifiable risk to water users of exposure to 3GC-resistant E. coli.
Antibiotic-resistant bacteria (ARB) present a global public health problem. With numbers of community-acquired resistant infections increasing, understanding the mechanisms by which people are ...exposed to and colonised by ARB can help inform effective strategies to prevent their spread. The role natural environments play in this is poorly understood. This is the first study to combine surveillance of ARB in bathing waters, human exposure estimates and association between exposure and colonisation by ARB in water users.
97 bathing water samples from England and Wales were analysed for the proportion of E. coli harbouring blaCTX-M. These data were used to estimate the likelihood of water users ingesting blaCTX-M-bearing E. coli. Having identified surfers as being at risk of exposure to ARB, a cross-sectional study was conducted. Regular surfers and non-surfers were recruited to assess whether there is an association between surfing and gut colonisation by blaCTX-M-bearing E. coli.
11 of 97 bathing waters sampled were found to contain blaCTX-M-bearing E. coli. While the percentage of blaCTX-M-bearing E. coli in bathing waters was low (0.07%), water users are at risk of ingesting these ARB. It is estimated that over 2.5 million water sports sessions occurred in 2015 resulting in the ingestion of at least one blaCTX-M-bearing E. coli. In the epidemiological survey, 9/143 (6.3%) surfers were colonised by blaCTX-M-bearing E. coli, as compared to 2/130 (1.5%) of non-surfers (risk ratio=4.09, 95% CI 1.02 to 16.4, p=0.046).
Surfers are at risk of exposure to and colonisation by clinically important antibiotic-resistant E. coli in coastal waters. Further research must be done on the role natural environments play in the transmission of ARB.
•E. coli in coastal waters harbour various blaCTX-M genes, which confer resistance to multiple beta-lactam antibiotics.•Surfers are at higher risk of ingesting CTX-M-producing E. coli while surfing than other water users.•Surfers are at a higher risk of being colonised by CTX-M-producing E. coli compared to non-surfers.
Karl von Frisch’s studies of bees’ color vision and chemical senses opened a window into the perceptual world of a species other than our own. A century of subsequent research on bees’ visual and ...olfactory systems has developed along two productive but independent trajectories, leaving the questions of how and why bees use these two senses in concert largely unexplored. Given current interest in multimodal communication and recently discovered interplay between olfaction and vision in humans and Drosophila, understanding multisensory integration in bees is an opportunity to advance knowledge across fields. Using a classic ethological framework, we formulate proximate and ultimate perspectives on bees’ use of multisensory stimuli. We discuss interactions between scent and color in the context of bee cognition and perception, focusing on mechanistic and functional approaches, and we highlight opportunities to further explore the development and evolution of multisensory integration. We argue that although the visual and olfactory worlds of bees are perhaps the best-studied of any non-human species, research focusing on the interactions between these two sensory modalities is vitally needed.
The synthesis of secondary metabolites is a hallmark of plant defence against herbivores. These compounds may be detrimental to consumers, but can also protect herbivores against parasites. Floral ...nectar commonly contains secondary metabolites, but little is known about the impacts of nectar chemistry on pollinators, including bees. We hypothesized that nectar secondary metabolites could reduce bee parasite infection. We inoculated individual bumblebees with Crithidia bombi, an intestinal parasite, and tested effects of eight naturally occurring nectar chemicals on parasite population growth. Secondary metabolites strongly reduced parasite load, with significant effects of alkaloids, terpenoids and iridoid glycosides ranging from 61 to 81%. Using microcolonies, we also investigated costs and benefits of consuming anabasine, the compound with the strongest effect on parasites, in infected and uninfected bees. Anabasine increased time to egg laying, and Crithidia reduced bee survival. However, anabasine consumption did not mitigate the negative effects of Crithidia, and Crithidia infection did not alter anabasine consumption. Our novel results highlight that although secondary metabolites may not rescue survival in infected bees, they may play a vital role in mediating Crithidia transmission within and between colonies by reducing Crithidia infection intensities.
Numerous illnesses are associated with bathing in natural waters, although it is assumed that the risk of illness among bathers exposed to relatively clean waters found in high-income countries is ...negligible. A systematic review was carried out to quantify the increased risk of experiencing a range of adverse health outcomes among bathers exposed to coastal water compared with non-bathers.
In all 6919 potentially relevant titles and abstracts were screened, and from these 40 studies were eligible for inclusion in the review. Odds ratios (OR) were extracted from 19 of these reports and combined in random-effect meta-analyses for the following adverse health outcomes: incident cases of any illness, ear infections, gastrointestinal illness and infections caused by specific microorganisms.
There is an increased risk of experiencing symptoms of any illness OR = 1.86, 95% confidence interval (CI): 1.31 to 2.64, P = 0.001 and ear ailments (OR = 2.05, 95% CI: 1.49 to 2.82, P < 0.001) in bathers compared with non-bathers. There is also an increased risk of experiencing gastrointestinal ailments (OR = 1.29, 95% CI: 1.12 to 1.49, P < 0.001).
This is the first systematic review to evaluate evidence on the increased risk of acquiring illnesses from bathing in seawater compared with non-bathers. Our results support the notion that infections are acquired from bathing in coastal waters, and that bathers have a greater risk of experiencing a variety of illnesses compared with non-bathers.
1. Many floral displays are visually complex, transmitting multi-coloured patterns that are thought to direct pollinators to nectar rewards. These ' nectar guides' may be mutually beneficial, if they ...reduce pollinators' handling time, leading to an increased visitation rate and promoting pollen transfer. Yet, many details regarding how floral patterns influence foraging efficiency are unknown, as is the potential for pollinator learning to alter this relationship. 2. We compared the responses of bumblebee (Bombus impatiens Cresson) foragers to artificial flowers that either possessed or lacked star-like patterns. By presenting each bee with two different foraging scenarios (patterned flowers rewarding/plain flowers unrewarding, plain flowers rewarding/patterned flowers unrewarding) on different days, we were able to assess both short-and long-term effects of patterns on bee foraging behaviour. 3. Bees discovered rewards more quickly on patterned flowers and were less likely to miss the reward, regardless of whether corollas were circular or had petals. Nectar guides' effect on nectar discovery was immediate (innate) and persisted even after experience, although nectar discovery itself also had a learned component. We also found that bees departed patterned flowers sooner after feeding. Finally, when conditions changed such that flowers no longer provided a reward, bees visited the now-unrewarding flowers more persistently when they were patterned. 4. On the time-scale of a single foraging bout, our results provide some of the first data on how pollinators learn to forage efficiently using this common floral trait. Our bees' persistent response to patterned flowers even after rewards ceased suggests that, rather than being consistently mutually beneficial to plant and pollinator, nectar guide patterns can at times promote pollen transfer for the plant at the expense of a bee's foraging success.
Neonicotinoid pesticides are well-known for their sublethal effects on insect behavior and physiology. Recent work suggests neonicotinoids can impair insect olfactory processing, with potential ...downstream effects on behavior and possibly survival. However, it is unclear whether impairment occurs during peripheral olfactory detection, during information processing in central brain regions, or in both contexts. We used Drosophila melanogaster to explore the potential for neonicotinoids to disrupt olfaction by conducting electrophysiological analyses of single neurons and whole antennae of flies exposed to varying concentrations of the neonicotinoid imidacloprid (IMD) that were shown to cause relative differences in fly survival. Our results demonstrated that IMD exposure significantly reduced the activity of a single focal olfactory neuron and delayed the return to baseline activity of the whole antenna. To determine if IMD also impacts olfactory-guided behavior, we compared flies' relative preference for odor sources varying in ethanol content. Flies exposed to IMD had a greater relative preference for ethanol-laced pineapple juice than control flies, demonstrating that neuronal shifts induced by IMD that we observed are associated with changes in relative preference. Given the interest in the sensory impacts of agrochemical exposure on wild insect behavior and physiology, we highlight the potential of Drosophila as a tractable model for investigating the effects of pesticides at scales ranging from single-neuron physiology to olfactory-guided behavior.
Neonicotinoid pesticides can impair bees' ability to learn and remember information about flowers, critical for effective foraging. Although these effects on cognition may contribute to broader ...effects on health and performance, to date they have largely been assayed in simplified protocols that consider learning in a single sensory modality, usually olfaction. Given that real flowers display a variety of potentially useful signals, we assessed the effects of acute neonicotinoid exposure on multimodal learning in free-flying bumblebees. We found that neonicotinoid consumption differentially impacted learning of floral stimuli, impairing scent, but not colour, learning. These findings raise questions about the mechanisms by which pesticides might differentially impair sensory systems, with implications for how neonicotinoids affect multiple aspects of bee ecology.
As bees' main source of protein and lipids, pollen is critical for their development, reproduction, and health. Plant species vary considerably in the macronutrient content of their pollen, and ...research in bee model systems has established that this variation both modulates performance and guides floral choice. Yet, how variation in pollen chemistry shapes interactions between plants and bees in natural communities is an open question, essential for both understanding the nutritional dynamics of plant-pollinator mutualisms and informing their conservation. To fill this gap, we asked how pollen nutrition (relative protein and lipid content) sampled from 109 co-flowering plant species structured visitation patterns observed among 75 subgenera of pollen-collecting bees in the Great Basin/Eastern Sierra region (USA). We found that the degree of similarity in co-flowering plant species' pollen nutrition predicted similarity among their visitor communities, even after accounting for floral morphology and phylogeny. Consideration of pollen nutrition also shed light on the structure of this interaction network: Bee subgenera and plant genera were arranged into distinct, interconnected groups, delineated by differences in pollen macronutrient values, revealing potential nutritional niches. Importantly, variation in pollen nutrition alone (high in protein, high in lipid, or balanced) did not predict the diversity of bee visitors, indicating that plant species offering complementary pollen nutrition may be equally valuable in supporting bee diversity. Nutritional diversity should thus be a key consideration when selecting plants for habitat restoration, and a nutritionally explicit perspective is needed when considering reward systems involved in the community ecology of pollination.
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