Varroa destructor and viruses association in honey bee colonies under different climatic conditions.

Honey bee colonies are threatened by multiple factors including complex interactions between environmental and diseases such as parasitic mites and viruses. We compared the presence of honeybee-pathogenic viruses and Varroa infestation rate in four apiaries: commercial colonies that received treatment against Varroa and non-treated colonies that did not received any treatment for the last 4 years located in temperate and subtropical climate. In addition, we evaluated the effect of climate and Varroa treatment on deformed wing virus (DWV) amounts. In both climates, DWV was the most prevalent virus, being the only present virus in subtropical colonies. Moreover, colonies from subtropical climate also showed reduced DWV amounts and lower Varroa infestation rates than colonies from temperate climate. Nevertheless, non-treated colonies in both climate conditions are able to survive several years. Environment appears as a key factor interacting with local bee populations and influencing colony survival beyond Varroa and virus presence.

Effect of Lactobacillus johnsonii CRL1647 on different parameters of honeybee colonies and bacterial populations of the bee gut.

Lactobacillus johnsonii CRL1647, isolated from the intestinal tract of a worker-bee in Salta, Argentina, was delivered to Apis mellifera L. honey bee colonies according to two different administration schedules: 1×10(5) cfu/ml every 15 days (2011) or monthly (2012). The effect of each treatment on the bee-colony performance was monitored by measuring honey production, and the prevalence of varroasis and nosemosis. Worker bees from each assay were randomly captured 3 days after administration and assayed for the following intestinal culturable and defined bacterial populations: total aerobic microorganisms, Bacillus spp. spores, Lactobacillus spp., Enterococcus spp. and enterobacteria. Interestingly, both treatments generated a similar increase in honey production in treated colonies compared to controls: 36.8% (every 15 days) and 36.3% (monthly). Nosema index always exhibited a reduction when lactobacilli were administered; in turn, Varroa incidence was lower when the lactobacilli were administered once a month. Moreover, the administration of L. johnsonii CRL1647 every 15 days produced an increase in the total number of aerobic microorganisms and in bacteria belonging to the genera Lactobacillus and Enterococcus; at the same time, a decrease was observed in the number of total spores at the end of the treatment. The number of enterobacteria was constant and remained below that of control hives at the end of the assay. On the other hand, the delivery of lactobacilli once a month only showed an increase in the number of bacteria belonging to the genus Lactobacillus; meanwhile, viable counts of the remaining microorganisms assayed were reduced. Even though it seems that both treatments were similar, those bee colonies that received L. johnsonii CRL1647 every 15 days became so strong that they swarmed.

Varroa destructor mite in Africanized honeybee colonies Apis mellifera L. under royal jelly or honey production / Varroa destructor em colônias de abelhas africanizadas Apis mellifera submetidas à produção de geleia real ou mel

This study evaluated the level of invasion of Varroa mite into worker brood cells, the infestation rate on adult worker honeybees, total and effective reproduction rates of the mite in Africanized honeybee colonies under royal jelly or honey production. Invasion and infestation rates were not statistically different between honeybee colonies producing honey or royal jelly and the averages for these parameters were 5.79 and 8.54%, respectively. Colonies producing honey presented a higher (p 0.05) total and effective reproduction of Varroa than colonies producing royal jelly. There was a negative correlation between levels of invasion and infestation with minimum external temperature, relative humidity and rainfall. The variables month and season influenced the development of the mite, but rates were low and within the range normally found in Brazil for Africanized honeybee colonies, which confirm the greater resistance of these honeybees to Varroa destructor than European honeybees.

O objetivo foi analisar o nível de invasão do ácaro nas pupas, a taxa de infestação do ácaro nas abelhas adultas, as taxas de reprodução total e efetiva do ácaro em colônias de abelhas africanizadas e se esses níveis são influenciados pela produção de geleia real ou mel. As taxas de invasão nas pupas e infestação nas abelhas adultas não apresentaram diferença estatística entre os tratamentos, as médias para esses parâmetros foram 5,79 e 8,54%, respectivamente. As colônias submetidas à produção de mel apresentaram maior nível de reprodução total e efetiva (p 0,05) do ácaro em relação às colônias produtoras de geleia real. Houve correlação negativa dos níveis de invasão nas pupas e infestação nas abelhas adultas com a temperatura externa mínima, umidade relativa do ar e precipitação. As variáveis mês e o período do ano influenciaram o desenvolvimento do parasita, entretanto, as taxas obtidas foram baixas e dentro dos valores normalmente encontrados no Brasil para abelhas africanizadas.

Varroa destructor mite in Africanized honeybee colonies Apis mellifera L. under royal jelly or honey production / Varroa destructor em colônias de abelhas africanizadas Apis mellifera submetidas à produção de geleia real ou mel

This study evaluated the level of invasion of Varroa mite into worker brood cells, the infestation rate on adult worker honeybees, total and effective reproduction rates of the mite in Africanized honeybee colonies under royal jelly or honey production. Invasion and infestation rates were not statistically different between honeybee colonies producing honey or royal jelly and the averages for these parameters were 5.79 and 8.54%, respectively. Colonies producing honey presented a higher (p 0.05) total and effective reproduction of Varroa than colonies producing royal jelly. There was a negative correlation between levels of invasion and infestation with minimum external temperature, relative humidity and rainfall. The variables month and season influenced the development of the mite, but rates were low and within the range normally found in Brazil for Africanized honeybee colonies, which confirm the greater resistance of these honeybees to Varroa destructor than European honeybees.(AU)

O objetivo foi analisar o nível de invasão do ácaro nas pupas, a taxa de infestação do ácaro nas abelhas adultas, as taxas de reprodução total e efetiva do ácaro em colônias de abelhas africanizadas e se esses níveis são influenciados pela produção de geleia real ou mel. As taxas de invasão nas pupas e infestação nas abelhas adultas não apresentaram diferença estatística entre os tratamentos, as médias para esses parâmetros foram 5,79 e 8,54%, respectivamente. As colônias submetidas à produção de mel apresentaram maior nível de reprodução total e efetiva (p 0,05) do ácaro em relação às colônias produtoras de geleia real. Houve correlação negativa dos níveis de invasão nas pupas e infestação nas abelhas adultas com a temperatura externa mínima, umidade relativa do ar e precipitação. As variáveis mês e o período do ano influenciaram o desenvolvimento do parasita, entretanto, as taxas obtidas foram baixas e dentro dos valores normalmente encontrados no Brasil para abelhas africanizadas.(AU)

Reproduction of Varroa destructor and offspring mortality in worker and drone brood cells of Africanized honey bees.

Varroa destructor is known to be the most serious parasite of Apis mellifera worldwide. In order to reproduce varroa females enter worker or drone brood shortly before the cell is sealed. From March to December 2008, the reproductive rate and offspring mortality (mature and immature stages), focusing on male absence and male mortality of V. destructor, was investigated in naturally infested worker and drone brood of Africanized honey bees (AHB) in Costa Rica. Data were obtained from 388 to 403 single infested worker and drone brood cells, respectively. Mite fertility in worker and drone brood cells was 88.9 and 93.1%, respectively. There was no difference between the groups (X(2) = 3.6, P = 0.06). However, one of the most significant differences in mite reproduction was the higher percentage of mites producing viable offspring in drone cells (64.8%) compared to worker cells (37.6%) (X(2) = 57.2, P < 0.05). A greater proportion of mites in worker brood cells produced non-viable female offspring. Mite offspring mortality in both worker and drone cells was high in the protonymph stage (mobile and immobile). A significant finding was the high rate of male mortality. The worker and drone brood revealed that 23.9 and 6.9%, respectively, of the adult male offspring was found dead. If the absence (missing) of the male and adult male mortality are taken together the percentage of cells increased to 40.0 and 21.3% in worker and drone cells, respectively (X(2) = 28.8, P < 0.05). The absence of the male or male mortality in a considerable number of worker cells naturally infested with varroa is the major factor in our study which reduces the production of viable daughters in AHB colonies in Costa Rica.