Nosemosis, a disease caused by a microsporidian infection, is one of the most frequently observed parasitic pathologies affecting adult honeybees. Presently, Nosema ceranae seems to be the main microsporidian infection in Apis mellifera. The antibiotic fumagillin is the only compound available to treat Nosema diseases; however, it is no longer licensed in most EU member states; therefore, the need to identify new molecules/substances prevails. The intent of this paper is to test bacterial metabolites by Bacillus and Enterococcus strains, isolated from bee midgut and honey. The toxicity on bees and the antiparasitic activity on N. ceranae were assessed under laboratory conditions. Results did not yield toxicity for the administered surfactin or bacteriocin concentrations. Spores exposed to direct contact with a particular surfactin revealed a significant infectivity reduction when inoculated on bees. This surfactin, administered ad libitum from the individuals' emergence, led to a significant reduction in parasitosis development when bees were infected with untreated spores 7 days postemergence. Based on the results obtained, one of the surfactins is herein postulated as a molecule capable of reducing N. ceranae development, acting either by direct exposure to purified spores or incorporated into the digestive tract of the bee.

To investigate the effect of nutritional condition of the honey bee Apis mellifera on the development of the microsporidian parasite Nosema ceranae under laboratory conditions, newly emerged bees were confined and fed on three ad libitum diets: high fructose corn syrup (HFCS) + fresh bee bread; HFCS + a commercial mixture of amino acid and vitamin, and HFCS. On day 7 post-emergence, bees from each diet treatment were individually infected with 4.60 x 10 4 , 2.30 x 10 5 or 1.15 x 10 6 spores of N. ceranae, keeping later on the same diet. On days 3, 6, 9, and 12, post-infection bee midguts were removed to individually quantify the spores developed. The results indicate that this parasite multiplies successfully regardless of the inoculum given or the nutritional status of its host. When bees are fed on pollen, however, the parasite develops quickly, exhibiting significantly higher intensities than under other treatments. The longevity of infected bees fed on the same diet was not affected by the degree of parasitism, but by the quality of the ad libitum diet administered. The data demonstrate a parasite development that depends on host-condition. This should be considered when designing experiments to evaluate the development and virulence of this pathogen. Desarrollo de Nosema ceranae en Apis mellifera: influencia de la dieta y el inoculado infectivo Resumen Para estudiar el efecto de la condición nutricional de obreras de Apis mellifera sobre el desarrollo de Nosema ceranae, se confinaron abejas recién emergidas y se sometieron a alimentación ad libitum con tres dietas diferentes: jarabe de alta fructosa (HFCS) + polen fresco ensilado; HFCS + mezcla comercial de aminoácidos y vitaminas, y una tercera de HFCS. Siete días luego de la emergencia, cada tratamiento nutricio fue subdividido en tres grupos y sus individuos fueron individualmente infectados con 4.60 x 10 4 , 2.30 x 10 5 o 1.15 x 10 6 esporos de N. ceranae, manteniéndose luego la dieta previa a la infección. A los 3, 6, 9 y 12 días posteriores a la infección se sacrificaron abejas para obtener el ventrículo y cuantificar individualmente el número de esporos presentes. Los resultados demuestran que este parásito se multiplica exitosamente, independientemente del inóculo administrado y del estado nutricional de su hospedador. De todos modos, cuando las obreras son alimentadas con polen fresco, la infección se desarrolla rápidamente, mostrando intensidades significativamente mayores a las desarrolladas bajo otros tratamientos. La longevidad de los individuos infectados y alimentados con la misma dieta no fue afectada del grado de parasitismo desarrollado, sino por la calidad de la dieta administrada. Los datos nos muestran un desarrollo del parásito que es dependiente de la condición del hospedador, y por lo tanto, deberían ser considerados cuando se diseñan experimentos para evaluar el desarrollo y la virulencia de este patógeno.

Using molecular techniques, we documented the presence of Nosema ceranae in honeybees (Apis mellífera) from Argentina. Samples were collected from A. mellifera colonies in 38 districts of Buenos Aires province, Argentina. Molecular characterization was achieved with a multiplex PCR-based method, which allows parallel diagnosis of N. ceranae and N. osema apis. N. ceranae was identified in all the samples analyzed. Moreover, coinfections with N. apis were detected in Balcarce and Maipú districts. We identified three rRNA sequence variants of N. ceranae, which may represent diverse sources of bee importation. The results suggest that N. ceranae is widely distributed in Argentina and that the genetic variation observed between the different isolates could be related with the difference in the symptomatology found previously by our work group. Our results highlight the need to re-assess the health protocols currently in force so that they recognize N. ceranae as the main causal agent of Nosemosis in this country.

This study evaluated the activity of plant extracts on Nosema ceranae development and their toxicity on the infected host Apis mellifera. Newly emerged bees were fed ad libitum with enriched syrups after individual infection. Diets consisted of ethanolic extracts obtained from Artemisia absinthium, Allium sativum, Laurus nobilis, and Ilex paraguariensis diluted in syrup at 1% and 10% concentrations. Examination of individual midgut homogenates on day 19 post-infection indicated that 1% concentration of L. nobilis extract significantly inhibited N. ceranae development. Absinth extract, previously reported as effective against Nosema apis, did not diminish the number of N. ceranae spores throughout the experiment. Ten percent concentrations showed high toxicity on infected bees, but also a significant activity diminishing parasitosis development in short periods. Syrups with the addition of extracts were consumed avidly as the control, even more in some cases. The present study constitutes the first report of antiparasitic activity in vivo of plant extracts against the Microsporidian N. ceranae and postulate natural substances as an alternative for antiparasitic treatment.Apis mellifera / Nosema ceranae / plant extract / antiparasitic treatment

-An organic product based on oxalic acid was evaluated for use in Varroa control under spring/summer climatic conditions in Argentina. The formulation consists of four strips made of cellulose impregnated with a solution based on oxalid acid. Forty-eight beehives were used to assess the product efficacy. Residues of the product were also tested in honey, bees, and wax. Each trial had respective control groups without oxalic treatment. At the beginning of the experiment, four strips of the formulation were applied to the colonies belonging to the treated group. Falling mites were counted after 7, 14, 21, 28, 35, and 42 days. After the last count, the strips were removed and colonies received two flumethrin strips for 45 days. Falling mites were counted throughout this period. Average efficacy of the organic product was 93.1 % with low variability. This product is an organic treatment designed for Varroa control during brood presence and represents a good alternative to the synthetic treatments.Varroa destructor / control / oxalic acid / bee brood / Argentina

Wild pollinators are declining and the number of managed honey bee colonies is growing slower than agricultural demands for pollination. Because of these contrasting trends in pollinator demand and availability, breeding programs for many pollinator-dependent crops have focused on reducing the need for pollinators. Although numerous crop varieties are now available in the market with the label of pollinator-independent, the real dependence of these varieties on pollinators is mostly unknown. We evaluated the hypothesis of pollinator independence in the Independence almond variety, the fastest growing variety in california that is the main almond production region in the world. in this presumed pollinator-independent variety, we measured the effect of honey bees on fruit set, yield, and kernel nutritional quality at tree level. Fruit set was 60% higher in bee-pollinated than bee-isolated trees, which translated into a 20% increase in kernel yield. Despite its effect on almond production, there was no evidence that bee visitation affected almond nutritional quality. Based on these results, we recommend the use of bees, whether they are wild or managed, to maximize yield even in self-fertile almond varieties.Dependence on animal pollination is increasing in global agriculture 1 . In 2005, the total estimated value of pollination worldwide was about $172 billion and accounted for nearly 10% of the world's agricultural crop production consumed by humans 2 . However, this percentage is increasing year after year as the area cultivated with pollinator-dependent crops is continuously expanding 3 . Unfortunately, wild pollinators are declining whereas managed honey bees are growing slower than agricultural demands for pollination 4,5 . Because of these uneven trends in pollinator demand and availability, breeding programs for many pollinator-dependent crops are targeted to reducing the need of biotic transfer of pollen for ovule fertilization, and thus for seed and fruit production. Many varieties of several typically pollinator-dependent crops are now available in the market with the label of "self-fertile" and sold as pollinator-independent. However, the extent to which these varieties depend on pollinators for either yield quantity or quality under field conditions is unknown.Almond (Prunus dulcis) production in California, USA, clearly illustrates this trend. California produces more than 80% of world's almonds, and the area devoted to this crop is continuously growing 6,7 . For decades, almond varieties cultivated in California have been self-incompatible and growers have relied almost exclusively on managed honey bees (Apis mellifera) for pollen transfer and effective pollination 8,9 . Because of almond's high pollinator-dependence and high-market value, more than a million honey bee colonies are moved to California from all over the U.S. every season, representing the largest man-driven pollination event in the world 10,11 . However, the number of honey bee colonies has been dwindling in the U.S. over the last deca...

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