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AbstractBombus pauloensisis a native bumble bee species widely distributed over South America and a key pollinator for native plants and commercial crops. This species is affected by pathogens such as Nosema ceranae, Crithidia bombiand Apis melliferaFilamentous Virus (AmFV). This work aims to document the presence and intensity of exogenous pathogens on the native bumble bee B. pauloensisin different periods of the year during spring and summer. Bumble bees were sampled in four study areas with contrasting land uses to preliminary evaluate if anthropization levels can be related to the presence and intensity of pathogens. DNA was isolated from twenty individuals per sampling site and N. ceranae, C. bombiand AmFV pathogens load were quantified by quantitative PCR. The results showed a wide and ubiquitous prevalence of N. ceranaeand C. bombipathogens in all the sampled bumble bees throughout the year, with a pathogens load that did not differ significantly among the sampling sites. AmFV was undetected in any of the individuals analyzed in any sampling site. This suggests that human activities could equally impact all habitats populated by B. pauloensis. Honey bees were detected with a relevant abundance in all the sampling sites and could be one of the main anthropogenic drivers of pathogens spread and host switches in the analyzed sampling sites. This study analyzes the general occurrence of the prevalence and intensity of the pathogens in a native Argentinian bumble bee species and attempts the correlation with the land use

Although many honey bee RNA viruses have been correlated with colony declines, little is known regarding the potential role of DNA viruses. Apis melliferafilamentous virus (AmFV) is a large double stranded DNA virus of honey bees and its prevalence and relationship with other parasites is poorly known. In the present work, we have described a high prevalence of AmFV in Argentinian apiaries, and a retrospective survey of archived honey bee samples revealed that AmFV has been present in Argentina since at least 2006. This is the first report involving AmFV in South America.

African honey bee subspecies Apis mellifera scutellatabegan to spread in the American continent from southern Brazil in 1956. The process of Africanization involved both maternal and paternal bidirectional gene flow between European and Africanized honey bees. In Argentina, Africanized honey bees dominate in the northern semitropical regions and a hybrid area is defined between (ca. 32°–34°latitude). Although previous analysis has been carried out in Buenos Aires province, no analysis has been made south of this latitude. We used mitochondrial DNA (mtDNA) assays and wing geometric morphometrics to determine the prevalence of Africanized honey bees in managed populations. African mitotype origin and subspecies identity, were determined at three regions from Argentina. In our study, we analyzed 480 samples by wing morphometry and 157 by cytochrome-b assays, collected during 2013–2016. Our results show that North of 35°N latitude, honey bees with African mitotype were quite common (88.64%) finding high similarity with A. m. scutellata. South of that latitude, in temperate regions, we found African mitotype in only 18 of 133 colonies analyzed and a mixture of both European (A. m. ligustica, A. m. cárnica, A. m. mellifera) and African subspecies, most likely derived from North African honey bee (A. m. intermissa). Our results confirmed the existence of Africanized honey bee populations with a gradual cline from north to south, as a result from recent A. m. scutellata-derived bee expansion. Beyond the transition area between the 30°–35°S parallels bees carrying the European mitotype were fairly common.

Apis melliferafilamentous virus (AmFV) is a large double stranded DNA virus of honey bees and its prevalence and relationship with other parasites is poorly known. Samples consisted of fifty-one adult bees belonging to eight native species collected using entomological nets in six provinces of Argentina, from 2009 to 2018. Total genomic DNA was extracted from individual bees and a 551 bp fragment of the Bro-N gene of AmFV was amplified by qPCR. In the present work we have reported for the first time both the presence and the wide geographic distribution of AmFV in Argentinian species of native bees. This is the first report of the presence of this virus associated with Xylocopa atamisquensis, X. augusti, X. frontalis, X. spendidula, Bombus pauloensisand Peponapis fervens. Detecting pathogens that could threaten native bee health is of outmost importance to generate both conservation and management strategies.

Varroa destructor (Anderson & Trueman, 2000) causes the most important parasitosis of beekeeping in the world. For this reason, prevention is needed to avoid colony death. The most typical treatments involve synthetic acaricides. However, the use of these acaricides results in the emergence of resistant populations of mites to these products and in the appearances of drug residues in products of the hives. Compounds of essential oils have emerged as an alternative to traditional acaricides; however the toxicity produced by these mixtures is currently poorly explored. The aim of this work was to assess, by means of in vitro tests with adult bees, how acaricidal action and toxic interactions in a binary mixture of essential oil compounds (Thymol, Phellandrene, Eucalyptol, Cinnamaldehyde, Myrcene, and Carvacrol) affect V. destructor. Calculations of LC50 ’s of the individual compounds on A. mellifera and V. destructor made clear that the toxic effect of each compound is different for both species. Thymol and Phellandrene turned out to be lethal for mites at lower concentrations than for bees. The binary mixture of these two substances presented a different toxicity than one produced by each pure compound, as it was highly selective for mites in bioassays at 24 hours through complete exposure to both A. mellifera and V. destructor. These results make such formulations optimal substances to be considered as alternative controls for the parasitosis.

The honey bee tracheal mite Acarapis woodi(Rennie) (Acari: Tarsonemidae) is an internal obligate parasite of the respiratory system of adult honey bees (Apis mellifera), which may be one of the factors causing the loss of bee colonies and the decrease in the beekeeping industry. In Argentina, the last prevalence study of A. woodiwas in 1998, and therefore there is no current data on the prevalence and impact of the mite in colonies of A. melliferain this country. For this reason, the objective of this study was to determine the prevalence of A. woodiin honey bee colonies of apiaries belonging to different geographic regions of Argentina (Northwest, Chaco, Mesopotamic, Pampean and Patagonic) using two different methods of diagnosis. One method was traditional microscopy, which is based on direct visualization of A. woodiin the prothoracic tracheas of bees, and the other technique was molecular analysis using real-time PCR with specific primers to amplify CO1 gene of A. woodi. To perform the analysis of prevalence, bees were collected during winter, because during this season, populations of A. woodiare more abundant in bee colonies. The results were negative for both methods of diagnosis, with prevalence equal to 0%. Considering that in recent years it has been reported an increased mortality in bee colonies in Argentina, we note that acarapisosis is not currently impacting on the disappearance of A. melliferacolonies in Argentina.

Varroa destructoris the most serious parasitic mite that infests the honey bee Apis mellifera. Different treatments with systemic acaricides are applied to control, but due to the intensive use of these chemicals, resistance to organophosphates and pyrethroids has developed worldwide. Most of the resistance episodes have been registered for fluvalinate, and only in a few cases has flumethrin resistance been reported. In Uruguay, no studies on V. destructorresistance to flumethrin have yet been recorded. High infestation levels of V. destructorare continuously detected in colonies of A. melliferaafter treatments with flumethrin. Hence, this study aimed to estimate the possible resistance to flumethrin of a V. destructorpopulation from the Colonia Department. Furthermore, the LC50baseline levels for flumethrin in two Uruguayan populations were determinated. The LC50for flumethrin for the population from Colonia Department was 3.8 μg/Petri dish, which means an increase of 34.5 fold when compared to the corresponding baseline, suggesting the development of resistance. These results are the first report of resistance to flumethrin in V. destructorin Uruguay, and extend the knowledge of acaricide resistance in the country.