Excerpts from the thesis of Truong Anh Tuan

1. GENERAL INFORMATION:

– PhD candidate: TRƯƠNG ANH TUẤN (Mr.)

– Title: “Studying Sacbrood disease on native bees (Apis cerena) and imported bees (Apis mellifera) in Northern Vietnam and methods for prevention and control”.

– Major: Veterinary Microbiology                      Code: 62 62 50 10

– Scientific supervisors:

PGS.TS.Phùng Quốc Chướng and TS. Lê Quang Trung

– Training institution: National Institute of Veterinary Research

2.  CONTENTS

2.1. Research purposes and scope of the dissertation

The purpose of this study was to evaluate situation of Sac-brood disease on Apis cerana and Apis mellifera, being kelp and harvested in the North of Vietnam, to identify agents causing the disease and to apply alterative treatments for effective prevention and control against the disease.

2.2. Research methodology

The main methods applied in this study were to investigate and evaluate the percentage of Sac-brood virus on Apis cerana in Hoabinh, Hanoi, Hungyen provinces and ong A. mellifera in Sonla, Dienbien provinces using questionnaires and statistical analysis. RT-PCR and RT-PCR/RFLPs were employed to determine Sac-brood viruses (SBVs) causing Sac-brood disease. Traditional approaches were used to extract ribonuclease enzyme (RNase) from cow’s pancreas and to do experiments of biological methods,  medicament using Rnase and IPM application for prevention and treatment of Sacbrood disease on A. mellifera. The best trial on A. mellifera would be selected to prevent and treat the disease on A. cerana.

 2.3. Major results and conclusions:

– Sacbood disease level on both honeybee species was highest during Spring and Autumn-Winter inter-seasons. Incidence of the disease was negative correlation to temperature and rainfall. Apiary size was not related to level of Sacbrood disease. Of 2 beekeeping models, the inter-provincial movement revealed lesser percentage of diseased colonies than the local movement model.

– On both honey bee species in the North, the agent of Sacbrood disease on A. mellifera was AmSBV with molecular marker of 335bp, and on A. cerana was AcCSBV showiwith molecular marker of 124bp and 211bp when using RT-PCR/RFLP techniques.

.- The highest effectiveness after 90 days of treatment to control against Sacbrood disease was to use RNase with the following medicaments: 1) spraying directly on worker bees inside diseased colonies with solution of RNAse and sugar (ratio 1:9 in volume) with dose of 40ml of the solution/8-frame colony; 3 times/cycles anf 4 day interval of 2 cycles; 2) Feeding a diseased colony 100ml of RNase and sugar solution (ratio 1:100 in volume) per night. The treatment lasts 5 durations with 3 feeding nights per duration. Interval between 2 durations was 4 days.

Scientific significance:

The results of the study provide additional scientific literatures for bee disease studies in Vietnam and references to the researchers, teachers and beekeepers.

Practical significance:

The obtained results are the scientific significance for Sacbrood disease diagnosis, provide an effective prevention and control of the disease using RNase, which is less negative affection to the bees, saves time of beekeepers and reduces residues in honeybee products. Results of this study will improve economic and social effectiveness so as to contribute sustainable development of the beekeeping industry in Vietnam.

Hà Nội, ngày       tháng 12 năm 2014

NEW CONTRIBUTIONS OF THE DSSERTATION

 This is the first systematical study about Sacbrood disease on both domestic bee (Apis cerana) and imported bees (Apis mellifera), which are kept and harvested in the North of Vietnam. The research also develops molecular markers to accurate and quick diagnoses of the disease. In addition, the thesis also contributes an effective approach on using biological management combined with RNase treatment to prevent and control against Sacbrood disease.