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Large-scale honey bee colony losses reported around the world have been associated with intoxication with pesticides, as with the presence of pests and pathogens. Among pesticides, neonicotinoid insecticides are the biggest threat. Due to their extensive use, they can be found in all agricultural environments, including soil, water, and air, are persistent in the environment, and are highly toxic for honey bees. In addition, infection by different pests and pathogens can act synergistically, weakening bees. In this study, we investigated the effects of chronic exposure to sublethal doses of imidacloprid alone or combined with the microsporidia Nosema ceranae on the immune response, deformed wing virus infection (DWV), gut microbiota, and survival of Africanized honey bees. We found that imidacloprid affected the expression of some genes associated with immunity generating an altered physiological state, although it did not favor DWV or N. ceranae infection. The pesticide alone did not affect honey bee gut microbiota, as previously suggested, but when administered to N. ceranae infected bees, it generated significant changes. Finally, both stress factors caused high mortality rates. Those results illustrate the negative impact of imidacloprid alone or combined with N. ceranae on Africanized honey bees and are useful to understand colony losses in Latin America. [ABSTRACT FROM AUTHOR]

High rates of honey bee colony losses have been reported worldwide; however, data about colony loss rates in South America is scarce. This study quantified colony losses experienced in Uruguay during the 2013-2014 season and identifies the self-diagnosed causes for these losses. An estimated 2.6% of all Uruguayan beekeepers, who collectively managed 5% of the estimated 550,000 colonies in the country, responded to this survey. We found that total summer and winter losses were similar (summer 19.0% (95% CI 13.26-24.77%), winter 20.2% (95% CI 14.98-25.39)), as were the average operational losses (summer 19.8% (95% CI 14.01-25.52), winter 18.3% (95% CI 13.15-23.56%)). The total annual loss was 28.5% (95% CI 22.42-34.51%), with each beekeeper losing, on average, 28.6% (95% CI 22.52-34.61%) of the colonies in their operation. Loss rates were similar across operations of different sizes. Queen failure, diseases and parasites, and pesticides were the leading self-reported and self-diagnosed causes of colony losses. This study is the first to document honey bee colony losses in Uruguay, establishing a baseline for future long-term monitoring. [ABSTRACT FROM AUTHOR]

Honeybees are susceptible to a wide range of pathogens, which have been related to the occurrence of colony loss episodes reported mainly in north hemisphere countries. Their ability to resist those infections is compromised if they are malnourished or exposed to pesticides. The aim of the present study was to carry out an epidemiological study in Uruguay, South America, in order to evaluate the dynamics and interaction of honeybee pathogens and evaluate their association with the presence of external stress factors such as restricted pollen diversity and presence of agrochemicals. We monitored 40 colonies in two apiaries over 24 months, regularly quantifying colony strength, parasite and pathogen status, and pollen diversity. Chlorinated pesticides, phosphorus, pyrethroid, fipronil, or sulfas were not found in stored pollen in any colony or season. Varroa destructor was widespread in March (end of summer-beginning of autumn), decreasing after acaricide treatments. Viruses ABPV, DWV, and SBV presented a similar trend, while IAPV and KBV were not detected. Nosema ceranae was detected along the year while Nosema apis was detected only in one sample. Fifteen percent of the colonies died, being associated to high V. destructor mite load in March and high N. ceranae spore loads in September. Although similar results have been reported in north hemisphere countries, this is the first study of these characteristics in Uruguay, highlighting the regional importance. On the other side, colonies with pollen of diverse botanical origins showed reduced viral infection levels, suggesting that an adequate nutrition is important for the development of healthy colonies. [ABSTRACT FROM AUTHOR]

The Africanization process of the honeybee Apis mellifera in America is considered one of the most spectacular biological invasions documented so far. It started in São Paulo (Brazil) in 1956 and the process has extended to almost all the continent (from the United States, to Argentina and Uruguay). The aim of this study was to evaluate the present status of Africanization in Uruguay after 40 years of its entrance, as well as to determine the circulating honeybee haplotypes through genetic (mitochondrial DNA) and morphometric approaches. Results showed that Africanized bees are completely established in Uruguay, representing 80 % of the analyzed colonies, distributed throughout the whole country. A great genetic diversity was found, detecting eight different haplotypes. Some of them have been previously reported in the country, while others are new. The persistence of the non-African haplotypes in western provinces (Paysandú, Río Negro, Soriano and Colonia) may be due to a strong importation of European queens. This fact is probably avoiding the complete Africanization of the Uruguayan colonies. [ABSTRACT FROM AUTHOR]

Two microsporidia species have been shown to infect Apis mellifera, Nosema apis and Nosema ceranae. This work present evidence that N. ceranae infection significantly suppresses the honey bee immune response, although this effect was not observed following infection with N. apis. Immune suppression would also increase susceptibility to other bee pathogens and senescence. Despite the importance of both Nosema species in honey bee health, there is no information about their effect on the bees' immune system and present results can explain the different virulence between both microsporida infecting honeybees. [ABSTRACT FROM AUTHOR]

Glyphosate is the most used pesticide around the world. Although different studies have evidenced its negative effect on honey bees, including detrimental impacts on behavior, cognitive, sensory and developmental abilities, its use continues to grow. Recent studies have shown that it also alters the composition of the honey bee gut microbiota. In this study we explored the impact of chronic exposure to sublethal doses of glyphosate on the honey bee gut microbiota and its effects on the immune response, infection by Nosema ceranae and Deformed wing virus (DWV) and honey bee survival. Glyphosate combined with N. ceranae infection altered the structure and composition of the honey bee gut microbiota, for example by decreasing the relative abundance of the core members Snodgrassella alvi and Lactobacillus apis. Glyphosate increased the expression of some immune genes, possibly representing a physiological response to mitigate its negative effects. However, this response was not sufficient to maintain honey bee health, as glyphosate promoted the replication of DWV and decreased the expression of vitellogenin, which were accompanied by a reduced life span. Infection by N. ceranae also alters honey bee immunity although no synergistic effect with glyphosate was observed. These results corroborate previous findings suggesting deleterious effects of widespread use of glyphosate on honey bee health, and they contribute to elucidate the physiological mechanisms underlying a global decline of pollination services. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Lotmaria passim was detected in honey bees from Uruguay, Argentina and Chile. • This trypanosomatid was detected in European and Africanized bees. • L. passim infected colonies showed high V. destructor parasitization level. • Crithidia mellificae was not detected. Abstract Trypanosomatids affecting honey bees, Crithidia mellificae and Lotmaria passim, have been poorly studied in South America. We therefore analyzed their presence in Africanized and European honeybees from Uruguay, Argentina and Chile collected between 1990 and 2011 and assessed their association with other bee parasites and pathogens. Crithidia mellificae was not detected while L. passim was wide-spread. This report shows that L. passim has been present in this region at least since 2007 and it infects both Africanized and European honey bees. L. passim infected colonies showed high V. destructor parasitization levels, suggesting an association between them. [ABSTRACT FROM AUTHOR]

Abstract: The mite Varroa destructor is an ectoparasite affecting honey bees worldwide. Synthetic acaricides have been among the principal tools available to beekeepers for its control, although several studies have shown its negative effects on honey bee physiology. Recent research suggests that those molecules strongly impact on immune signaling cascades and cellular immunity. In the present work, LC50 in six-day-old bees were determined for the following acaricides: tau-fluvalinate, flumethrin, amitraz and coumaphos. According to this obtained value, a group of individuals was treated with each acaricide and then processed for qPCR analysis. Transcript levels for genes encoding antimicrobial peptides and immune-related proteins were assessed. Flumethrin increased the expression of hymenoptaecin when comparing treated and control bees. Significant differences were recorded between coumaphos and flumethrin treatments, while the first one reduced the expression of hymenoptaecin and abaecin, the last one up-regulated their expressions. No significant statistically changes were recorded in the expression levels of vitellogenin, lysozyme or glucose dehydrogenase among bees treated with acaricides and control bees. This work constitutes the first report, under laboratory conditions, about induction of immune related genes in response to synthetic miticides. [Copyright &y& Elsevier]

Abstract: Mortality of honeybees is a serious problem that beekeepers have to face periodically in Uruguay and worldwide. The presence of RNA viruses, in addition to other pathogens may be one of its possible causes. In this work, we detected Chronic bee paralysis virus, Acute bee paralysis virus, Black queen cell virus, Sacbrood virus and Deformed wing virus in samples of Uruguayan honeybees with or without Varroa destructor and Nosema apis. The detection of viruses in different provinces, simultaneous co-infection of colonies by several viruses and the fact that 96% of the samples were infected with one or more virus, indicates they are widely spread in the region. [Copyright &y& Elsevier]

Abstract: Chronic bee paralysis virus (CBPV) causes a disease characterized by trembling, flightless, and crawling bees, while Acute bee paralysis virus (ABPV) is commonly detected in apparently healthy colonies, usually associated to Varroa destructor. Both viruses had been detected in most regions of the world, except in South America. In this work, we detected CBPV and ABPV in samples of Uruguayan honeybees by RT-PCR. The detection of both viruses in different provinces and the fact that most of the analyzed samples were infected, suggest that, they are widely spread in the region. This is the first record of the presence of CBPV and ABPV in Uruguay and South America. [Copyright &y& Elsevier]

Abstract: Paenibacillus larvae is the causative agent of American Foulbrood (AFB), a deleterious disease that affects honeybees. In Uruguay it was first reported in 1999. In 2001 the bacterium was spread all over the country, and its prevalence in honey was estimated in 51%. Two P. larvae genotypes were found; ERIC I – BOX A, worldwide distributed and ERIC I – BOX C, exclusively detected in Argentina until then. In the present manuscript we analyzed the evolution of AFB outbreaks from 1999 to 2009, presented a new nation-wide survey carried out during 2011 when a prevalence of 2% was found and discuss national strategies for prevention of the disease. Since Uruguay is a small country where almost all beekeepers are registered, Uruguayan experience can be useful to be applied in other countries. [Copyright &y& Elsevier]

American foulbrood is a severe bacterial disease affecting larvae of the honeybee Apis mellifera and it is caused by Paenibacillus larvae larvae. The disease is present worldwide and cases have been reported in almost all the beekeeping regions of the five continents. During 2001 and 2002 we carried out a nationwide study to assess the presence and amount of P. l. larvae spores in honey samples from Uruguay, combining classic bacteriological, and molecular approaches. The distribution of P. l. larvae spores in honey of the whole country showed a clear pattern and may provide useful data for a control and prevention strategy of American foulbrood. [Copyright &y& Elsevier]