Molecular Characterization of a New Nosema bombycis Strain Detected in Iranian Silkworm Farms.

PURPOSE: Pebrine as the most dangerous disease of silkworm mostly caused by Nosema species has caused huge economic losses. There is no information on the species and the genomic sequences of the pebrine-causing microsporidia in Iran. METHODS: In the present research, we tried to determine the sequences of two regions of rDNA using molecular methods. First, infected larvae and mother moths were collected from several farms in the north of Iran for identification and molecular characterization of microsporidian isolates. After extracting the spores and genomic DNA from the collected samples, two fragments of internal transcribed spacer (ITS) rDNA and small subunit (SSU) rDNA were amplified and sequenced, and registered in NCBI database and then, the phylogenetic tree was drawn. RESULTS: Results showed the obtained sequences (ITS rDNA: Accession No. MZ322002 and SSU rDNA: Accession No. MZ314703) represent a new strain of Nosema bombycis, which differs from the sequences deposited in the NCBI. CONCLUSION: The new N. bombycis strain identified in our study will help in control and management of the pebrine disease by specific detection of the infectious agent.

Distribution of Nosema Spp. in climatic regions of Iran.

Nosemosis is one of the most prevalent bee diseases in the world causing significant economic losses in the global bee-keeping industry. This cross-sectional study was conducted during April-September, 2016 to investigate the prevalence of nosemosis in different climatic regions of Iran. A total of 183 apiaries were selected based on cluster sampling and the climate of apiaries under study was classified using Domarten method. In each apiary, five percent of the colonies were randomly sampled. A total of 183 adult bee samples were taken and examined by microscopic and polymerase chain reaction (PCR) methods for the presence of Nosema infections. According to the results, infection caused by Nosema ceranae was observed in all regions under study. The prevalence of N. ceranae was 46.40% (42.70-50.10). However, infection with Nosema apis was not observed in the samples in either pure form or as associated infection. Based on the results of PCR, the prevalence of N. ceranae was 53.80% (46.60- 61.00) in humid, 71.00% (53.70-77.50) in semi-humid , 68.10% (61.40-74.80) in very humid, 29.40% (22.70-36.10) in arid, 34.30% (27.40-41.20) in semi- arid and 24.00% (17.90-30.00) in Mediterranean climates. The prevalence of infection in different climatic zones of the country was found to have significant differences (p < 0.001). According to the findings, N. ceranae was the only Nosema species in honeybees with a broad geographical dispersion in Iran. It seems that climate can influence the prevalence of mentioned parasite. .

Molecular detection of Nosema ceranae in the apiaries of Kurdistan province, Iran.

Nosema disease is one of the most important diseases of adult honey bees worldwide. It is known as silent killer because there are no characteristic symptoms. The aim of the present study was to determine prevalence of Nosema species in various towns of Kurdistan province in Iran. A multiplex polymerase chain reaction (multiplex-PCR) was performed for identification of Nosema species infecting European honeybee, Apis mellifera. A total of 100 samples were collected from apiaries (870 hives) in 10 counties of Kurdistan province, located in the west of Iran. Samples were examined using light microscope and PCR. The light microscope was used to determine the presence of Nosema spores in all of the collected samples. Multiplex-PCR based on 16S ribosomal RNA was used to differentiate N. apis from N. ceranae. Overall prevalence of the microscopic evaluation and PCR method were 29.00% and 32.00%, respectively. The analysis of Nosema isolates from interrogation of DNA databank entries of Kurdistan apiaries (based on rRNA sequence data) indicated that only N. ceranae was widespread in these apiaries, and it had already been found in high percentages (50.00%) in Marivan and Kamiaran counties of Kurdistan province. It was shown that only N. ceranae was found by PCR assay in the region.