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It has been suggested that the widespread use of neonicotinoid insecticides threatens bees, but research on this topic has been surrounded by controversy. In order to synthesize which research approaches have been used to examine the effect of neonicotinoids on bees and to identify knowledge gaps, we systematically reviewed research on this subject that was available on the Web of Science and PubMed in June 2015. Most of the 216 primary research studies were conducted in Europe or North America (82%), involved the neonicotinoid imidacloprid (78%), and concerned the western honey bee Apis mellifera (75%). Thus, little seems to be known about neonicotinoids and bees in areas outside Europe and North America. Furthermore, because there is considerable variation in ecological traits among bee taxa, studies on honey bees are not likely to fully predict impacts of neonicotinoids on other species. Studies on crops were dominated by seed-treated maize, oilseed rape (canola) and sunflower, whereas less is known about potential side effects on bees from the use of other application methods on insect pollinated fruit and vegetable crops, or on lawns and ornamental plants. Laboratory approaches were most common, and we suggest that their capability to infer real-world consequences are improved when combined with information from field studies about realistic exposures to neonicotinoids. Studies using field approaches often examined only bee exposure to neonicotinoids and more field studies are needed that measure impacts of exposure. Most studies measured effects on individual bees. We suggest that effects on the individual bee should be linked to both mechanisms at the sub-individual level and also to the consequences for the colony and wider bee populations. As bees are increasingly facing multiple interacting pressures future research needs to clarify the role of neonicotinoids in relative to other drivers of bee declines.

Lactic acid bacteria (LAB) are well recognized beneficial host-associated members of the microbiota of humans and animals. Yet LAB-associations of invertebrates have been poorly characterized and their functions remain obscure. Here we show that honeybees possess an abundant, diverse and ancient LAB microbiota in their honey crop with beneficial effects for bee health, defending them against microbial threats. Our studies of LAB in all extant honeybee species plus related apid bees reveal one of the largest collections of novel species from the genera Lactobacillus and Bifidobacterium ever discovered within a single insect and suggest a long (>80 mya) history of association. Bee associated microbiotas highlight Lactobacillus kunkeei as the dominant LAB member. Those showing potent antimicrobial properties are acquired by callow honey bee workers from nestmates and maintained within the crop in biofilms, though beekeeping management practices can negatively impact this microbiota. Prophylactic practices that enhance LAB, or supplementary feeding of LAB, may serve in integrated approaches to sustainable pollinator service provision. We anticipate this microbiota will become central to studies on honeybee health, including colony collapse disorder, and act as an exemplar case of insect-microbe symbiosis.

Neonicotinoid seed coating is associated with reduced density of wild bees, as well as reduced nesting of solitary bees and reduced colony growth and reproduction of bumblebees, but appears not to affect honeybees. Bees' responses to neonicotinoids examined Reports that neonicotinoid insecticides have adverse effects on bee populations remain controversial. Some studies have been criticized as using unrealistically high insecticide dosages or conditions far removed from those in the field, and it has been suggested that bees might be able to detect the insecticides and avoid treated crops. Two papers in this issue of Nature present results that fill some of the gaps in our knowledge. In laboratory experiments Sébastien Kessler et al . use field-level doses of three commonly used neonicotinoids — clothianidin, imidacloprid and thiamethoxam — to show that both honeybees and bumblebees are able to detect their presence. However, the bees do not avoid neonicotinoid-treated food and may even prefer it. Maj Rundlöf et al . sowed oilseed rape with and without a clothianidin seed coating in matched and replicated agricultural landscapes. They found the seed coating to be associated with reduced density of wild bees, as well as reduced nesting of solitary bees and reduced colony growth of bumblebees, but they did not detect an effect on honeybees. Understanding the effects of neonicotinoid insecticides on bees is vital because of reported declines in bee diversity and distribution 1 , 2 , 3 and the crucial role bees have as pollinators in ecosystems and agriculture 4 . Neonicotinoids are suspected to pose an unacceptable risk to bees, partly because of their systemic uptake in plants 5 , and the European Union has therefore introduced a moratorium on three neonicotinoids as seed coatings in flowering crops that attract bees 6 . The moratorium has been criticized for being based on weak evidence 7 , particularly because effects have mostly been measured on bees that have been artificially fed neonicotinoids 8 , 9 , 10 , 11 . Thus, the key question is how neonicotinoids influence bees, and wild bees in particular, in real-world agricultural landscapes 11 , 12 , 13 . Here we show that a commonly used insecticide seed coating in a flowering crop can have serious consequences for wild bees. In a study with replicated and matched landscapes, we found that seed coating with Elado, an insecticide containing a combination of the neonicotinoid clothianidin and the non-systemic pyrethroid β-cyfluthrin, applied to oilseed rape seeds, reduced wild bee density, solitary bee nesting, and bumblebee colony growth and reproduction under field conditions. Hence, such insecticidal use can pose a substantial risk to wild bees in agricultural landscapes, and the contribution of pesticides to the global decline of wild bees 1 , 2 , 3 may have been underestimated. The lack of a significant response in honeybee colonies suggests that reported pesticide effects on honeybees cannot always be extrapolated to wild bees.

Honey bee societies (Apis mellifera), the ectoparasitic mite Varroa destructor, and honey bee viruses that are vectored by the mite, form a complex system of host–parasite interactions. Coevolution by natural selection in this system has been hindered for European honey bee hosts since apicultural practices remove the mite and consequently the selective pressures required for such a process. An increasing mite population means increasing transmission opportunities for viruses that can quickly develop into severe infections, killing a bee colony. Remarkably, a few subpopulations in Europe have survived mite infestation for extended periods of over 10 years without management by beekeepers and offer the possibility to study their natural host–parasite coevolution. Our study shows that two of these “natural” honey bee populations, in Avignon, France and Gotland, Sweden, have in fact evolved resistant traits that reduce the fitness of the mite (measured as the reproductive success), thereby reducing the parasitic load within the colony to evade the development of overt viral infections. Mite reproductive success was reduced by about 30% in both populations. Detailed examinations of mite reproductive parameters suggest these geographically and genetically distinct populations favor different mechanisms of resistance, even though they have experienced similar selection pressures of mite infestation. Compared to unrelated control colonies in the same location, mites in the Avignon population had high levels of infertility while in Gotland there was a higher proportions of mites that delayed initiation of egg‐laying. Possible explanations for the observed rapid coevolution are discussed. European honey bees in two subset populations located in France and Sweden have demonstrated host adaptation to natural infestation levels of the parasitic mite, Varroa destructor. The mite's reproductive success was reduced almost equally in both populations by 30% compared to control colonies but the evolved mechanisms for this host resistance appear to be different between these populations.

Although pollinator declines are a global biodiversity threat, the demography of the western honeybee (Apis mellifera) has not been considered by conservationists because it is biased by the activity of beekeepers. To fill this gap in pollinator decline censuses and to provide a broad picture of the current status of honeybees across their natural range, we used microsatellite genetic markers to estimate colony densities and genetic diversity at different locations in Europe, Africa, and central Asia that had different patterns of land use. Genetic diversity and colony densities were highest in South Africa and lowest in Northern Europe and were correlated with mean annual temperature. Confounding factors not related to climate, however, are also likely to influence genetic diversity and colony densities in honeybee populations. Land use showed a significantly negative influence over genetic diversity and the density of honeybee colonies over all sampling locations. In Europe honeybees sampled in nature reserves had genetic diversity and colony densities similar to those sampled in agricultural landscapes, which suggests that the former are not wild but may have come from managed hives. Other results also support this idea: putative wild bees were rare in our European samples, and the mean estimated density of honeybee colonies on the continent closely resembled the reported mean number of managed hives. Current densities of European honeybee populations are in the same range as those found in the adverse climatic conditions of the Kalahari and Saharan deserts, which suggests that beekeeping activities do not compensate for the loss of wild colonies. Our findings highlight the importance of reconsidering the conservation status of honeybees in Europe and of regarding beekeeping not only as a profitable business for producing honey, but also as an essential component of biodiversity conservation.

Mites in the genus Tropilaelaps (Acari: Laelapidae) are ectoparasites of the brood of honey bees (Apis spp.). Different Tropilaelaps subspecies were originally described from Apis dorsata, but a host switch occurred to the Western honey bee, Apis mellifera, for which infestations can rapidly lead to colony death. Tropilaelaps is hence considered more dangerous to A. mellifera than the parasitic mite Varroa destructor. Honey bees are also infected by many different viruses, some of them associated with and vectored by V. destructor. In recent years, deformed wing virus (DWV) has become the most prevalent virus infection in honey bees associated with V. destructor. DWV is distributed world-wide, and found wherever the Varroa mite is found, although low levels of the virus can also be found in Varroa free colonies. The Varroa mite transmits viral particles when feeding on the haemolymph of pupae or adult bees. Both the Tropilaelaps mite and the Varroa mite feed on honey bee brood, but no observations of DWV in Tropilaelaps have so far been reported. In this study, quantitative real-time RT-PCR was used to show the presence of DWV in infested brood and Tropilaelaps mercedesae mites collected in China, and to demonstrate a close quantitative association between mite-infested pupae of A. mellifera and DWV infections. Phylogenetic analysis of the DWV sequences recovered from matching pupae and mites revealed considerable DWV sequence heterogeneity and polymorphism. These polymorphisms appeared to be associated with the individual brood cell, rather than with a particular host.

A sensitive hemi-nested polymerase chain reaction (PCR) was used for detection of Melissococcus plutonius, the causative agent of European foulbrood (EFB). Sampling was made in Switzerland, where EFB is a widespread disease and incidences have increased in recent years. Larvae from brood samples with and without clinical signs of disease (n = 92) and honey (n = 92) from the same colonies were investigated. Individual larvae (n = 60) and pupae (n = 30) from diseased brood in single colonies were also investigated to study the distribution of the bacterium within the brood between larvae. M. plutonius was detected in larvae in all apiaries where symptoms of EFB could be seen, but not in all colonies judged as cases of EFB in the field, when healthy-looking larvae from such colonies were tested. The occurrence of the bacterium within the brood was not limited to larvae with symptoms only, but was mainly found in diseased larvae. The bacterium was also found in pupae. Healthy-looking larvae-even from heavily diseased combs-failed, in a number of cases, to amplify product in the PCR. M. plutonius could only be detected in 35% of the brood nest honey from clinically diseased colonies.

The full statement should read: \"Alejandra Vasquez and Tobias Olofsson are the founders of and hold stocks in ConCellae AB, a biotech company that develops and markets functional food products, including honey-based products.Alejandra Vasquez and Tobias Olofsson are inventors and owners of a patent application related to the applications of Lactobacillus and Bifidobacterium strains isolated from honey.

It has been suggested that the widespread use of neonicotinoid insecticides threatens bees, but research on this topic has been surrounded by controversy. In order to synthesize which research approaches have been used to examine the effect of neonicotinoids on bees and to identify knowledge gaps, we systematically reviewed research on this subject that was available on the Web of Science and PubMed in June 2015. Most of the 216 primary research studies were conducted in Europe or North America (82%), involved the neonicotinoid imidacloprid (78%), and concerned the western honey bee Apis mellifera (75%). Thus, little seems to be known about neonicotinoids and bees in areas outside Europe and North America. Furthermore, because there is considerable variation in ecological traits among bee taxa, studies on honey bees are not likely to fully predict impacts of neonicotinoids on other species. Studies on crops were dominated by seed-treated maize, oilseed rape (canola) and sunflower, whereas less is known about potential side effects on bees from the use of other application methods on insect pollinated fruit and vegetable crops, or on lawns and ornamental plants. Laboratory approaches were most common, and we suggest that their capability to infer real-world consequences are improved when combined with information from field studies about realistic exposures to neonicotinoids. Studies using field approaches often examined only bee exposure to neonicotinoids and more field studies are needed that measure impacts of exposure. Most studies measured effects on individual bees. We suggest that effects on the individual bee should be linked to both mechanisms at the sub-individual level and also to the consequences for the colony and wider bee populations. As bees are increasingly facing multiple interacting pressures future research needs to clarify the role of neonicotinoids in relative to other drivers of bee declines.