No abstract

Honeybees are threatened by various pathogens and parasites. More than 18 viruses have been described in honeybees and many of them have been detected in China and Argentina. In China, both Apis cerana and Apis mellifera are raised. In Argentina, beekeepers raise different ecotypes of A. mellifera: European honeybees (in both temperate and subtropical regions) and Africanised honeybees (in subtropical areas only). A thorough study was carried out in both China and Argentina to analyse the current virus presence and distribution in different climatic zones and gather information on different bee species/subspecies. Adult honeybees were collected from apiaries in temperate and subtropical regions of China (including areas with exclusive populations of A. mellifera, areas where A. mellifera and A. cerana co-exist, and areas with exclusive populations of A. cerana) and Argentina. Six viruses, namely, deformed wing virus (DWV), black queen cell virus (BQCV), sacbrood virus (SBV), chronic bee paralysis virus (CBPV), acute bee paralysis virus (ABPV) and Israeli acute paralysis virus (IAPV) were detected in China, both in A. cerana and in A. mellifera, while four viruses (DWV, BQCV, CBPV and ABPV) were present in Argentina. Interestingly, multiple infections were commonly found in China, with up to five different viruses co-circulating in some colonies without apparent abnormalities. In this study, no Chinese samples were positive for slow bee paralysis virus. The most prevalent viruses were BQCV (China) and DWV (Argentina). Kashmir bee virus was absent from samples analysed for both countries.

Honeybee defensive behavior is a useful selection criterion, especially in areas with Africanized honeybees (Apis mellifera L). In all genetic improvement programs the selected characters must be measured with precision, and because of this we evaluated a metabolic method for testing honeybee defensive behavior in the laboratory for its usefulness in distinguishing between honeybee ecotypes and selecting honeybees based on their level of defensive responses. Ten honeybee colonies were used, five having been produced by feral queens from a subtropical region supposedly colonized by Africanized honeybees and five by queens from a temperate region apparently colonized by European honeybees. We evaluate honeybee defensive behavior using a metabolic test based on oxygen consumption after stimulation with an alarm pheromone, measuring the time to the first response, time to maximum oxygen consumption, duration of activity, oxygen consumption at first response, maximum oxygen consumption and total oxygen consumption, colonies being ranked according to the values obtained for each variable. Significant (p < 0.05) differences were detected between ecotypes for each variable but for all variables the highest rankings were obtained for colonies of subtropical origin, which had faster and more intense responses. All variables were highly associated (p < 0.05). Total oxygen consumption was the best indicator of metabolic activity for defensive behavior because it combined oxygen consumption and the length of the response. This laboratory method may be useful for evaluating the defensive behavior of honey bees in genetic programs designed to select less defensive bees.

American foulbrood (AFB), caused by the bacterium Paenibacillus larvae is a serious disease of honey bees worldwide that inflicts considerable economic losses on beekeepers. The aim of this investigation was to determine the spread of AFB in a commercial apiary headed by queens selected for hygienic behaviour (HB), and to estimate the agreement between microbiological methods for the isolation of P. larvae from honey samples (HS) or bee samples (BS). All work was undertaken in a commercial apiary that showed visual signs of AFB infection. Hives positive for AFB were isolated from the apiary and the queens of the remaining hives replaced by others selected for HB. The prevalence of AFB was then recorded by monitoring visual signs of the disease, and via the isolation of P. larvae spores from HS and BS. The hives showed no clinical signs of AFB although HS testing showed 50% to harbour P. larvae spores after one year. This percentage decreased to 26% by the end of the study. The spore loads of the HS and BS were low (between 0.33 and 5 CFU/plate for HS and 0.33 and 12 CFU/plate for BS). No agreement was seen between the two microbiological isolation methods as assessed by the Kappa coefficient (P > 0.05). Sixty percent false negatives were recorded for the HS method. The BS method was more sensitive and is the best option for the early diagnosis of AFB; this, plus the use of HB lines may be sufficient for the control of this disease.

Centro de investigaciones en CienciasAgronómicas y Veterinarias (CICVyA), Argentina Recently, BQCV was detected in Argentinean apiaries located along different geographic regions, with a prevalence of 8% [8]. Acute bee paralysis virus (ABPV) is a widespread bee pathogen that has been linked with colony losses [14]. Previous reports demonstrated highly increased percentage of infection by ABPV in Slovenian queen rearing apiaries [5]. ABPV usually shows low prevalence values and its detection is not associated with clinical signs. However, when the virus is present at high titers, elevated mortality rates are evident [14].