Battling with bee brood disease in Apis cerana in W. Nepal - Some findings (2000)
Naomi M. Saville
Paper for the Pests and Diseases Session of the 7th IBRA Conference on Tropical bees: management and diversity
& 5th Asian Apicultural Association Conference, 19-25 March 2000, Chang Mai, Thailand
Thai Sac Brood Virus (TSBV) disease has been described by Bailey (1982). First found in Thailand in 1976 (Aemprapa and Wongsiri 2000), TSBV spread to the state of Bihar in India by 1979 and hence from East to West within Northern India during the 1980s (Kshirsagar et al 1982, 1984, 1981). The first outbreak was devastating to Apis cerana bee populations in Nepal (Morse 1982). Underwood and Khatri (1985) reported that TSBV was found first in E. Nepal between 1978 and 1981. It took 4 years for the disease to sweep across the country, reaching all areas by 1984. They estimated that 72% of Apis cerana in 11 zones and 98% in 3 districts around Lumle were lost, resulting in an overall estimated 89% loss of colonies at that time. Populations made a quick recovery and the other 3 native bee species were not affected. However, A. mellifera inoculated with TSBV died (Underwood and Khatri 1985).
Since this first dramatic epidemic of TSBV in Nepal, levels of the disease have fluctuated in different parts of the country, still causing large scale absconding when disease levels get high. Arguably though nowadays TSBV is less deleterious to indigenous bees than European Foul Brood Disease (EFB). This disease almost certainly entered Nepal with introduced Apis mellifera in the early 1990s and since that time has become increasingly problematic. Unlike TSBV, it appears that EFB can affect Apis laboriosa and Apis dorsata. High levels of EFB were detected in brood combs of Apis dorsata in the plains of Nepal in 1994 (H. Pechhacker pers. comm) and declining populations of A. laboriosa are also reported in areas where EFB is common.
In the district of Jumla where ICIMOD conducted farmer participatory action research, Apis cerana cerana was identified as a valuable genetic resource with potential for matching Apis mellifera in terms of production and ease of management (Verma 1992, 1998). Despite this an attempt to introduce Apis mellifera to Jumla was made by an NGO around 1991. This probably introduced EFB into the district since colonies of Apis mellifera infected with EFB were identified in KTS apiary in 1994 (H. Pechhacker pers. comm.). TSBV was also found to be present in the experimental apiary at KTS and throughout the district. So, at the time of the ICIMOD project from 1995 - 1998, colonies were dying and absconding in large numbers. This meant that hive testing research broadened out into action research into bee brood disease control and farmer-led extension to assist beekeepers to control bee diseases.
1 Surveys to assess the impact of the diseases and associated extension activities
Two questionnaire surveys were conducted in Jumla district:
- In September and October 1996 for two 15-day periods 2-3 local extension workers interviewed 60 farmers from selected beekeeping areas; and
- Between May and September 1997, a team of 10-12 'farmer-trainers' interviewed 302 farmers from communities throughout the district.
The 'farmer-trainers' who conducted the surveys and extension work were lead beekeepers trained in bee diseases and extension. They completed some or all of the following activities in villages:
- completion of questionnaire survey forms (minimum 2 per village);
- inspection of combs (which usually have to be cut out from traditional log and wall hives);
- removal of diseased combs in colonies where the level of infection was serious and provision of queen gates to prevent absconding;
- completion of comb inspection records sheets and diagnosis of the problems (these may be starvation, pesticide poisoning, worker laying, as well as brood disease);
- taking smear samples of diseased brood from the colonies whose combs were cut;
- demonstrations on how to feed sugar syrup, 'Terramycin' antibiotics and herbal medicine;
- informal classes on:
- EFB and TSBV diseases using the combs cut to demonstrate and / or showing photographs of brood disease symptoms;
- beeswax purification, candle making and hand-cream making (with demonstration where possible);
- modifying log hives into log top-bar hives.
The questionnaires accessed information on indigenous knowledge of bee disease control practices, hive baiting practices, honey / wax harvesting, processing and subsequent usage, markets and prices, numbers of colonies and honey yields, disease symptoms observed, perceptions about the disease and so on.
2 Documenting Experiences with Disease Control Measures
In the course of battling with TSBV and EFB, experiences gained in disease control and colony management in the ICIMOD trial and demonstration apiary at Karnali Technical School (KTS), farmer-managed demonstration apiaries (using top-bar and frame hives) and traditional beekeepers' log and wall hives were carefully documented.
3 Training and Extension about Bee Diseases and their Control
After completing the disease survey in 1997 a district wide farmer-led extension programme was initiated 1997-1998 (Saville 2000). The purpose of this was to tackle the diseases by increasing awareness amongst farmers about how to prevent them, how to identify them and control measures to take once detected. In the spring of 1998 hive sanitation measures were taught to farmers to try to influence hive baiting practices and minimise sources of re-infection. These included scorching the hives with flames or pouring boiling water across the inner surfaces of the hives and drying them in the sun. Throughout 1998, farmer trainers provided training on basic beekeeping with emphasis on diagnostic symptoms of brood disease and control measures coupled with promotion of the Jumla top-bar hive, adapted from the traditional log or wall hive, which allows timely disease management to be undertaken.
To increase the value from beekeeping despite the losses of colonies, extension efforts concentrated on increasing awareness of the uses of beeswax (for candles, skin creams, polishes, etc). Establishment of a small enterprise for value addition to beeswax and marketing of beeswax products provided a market for farmers. Beeswax could be harvested from dead / absconded colonies and put to productive use. This helped farmers to benefit from bees despite severe losses of bee colonies and also removed diseased combs from empty hives, which would otherwise spread the diseases.
1 Results of disease surveys in 1996 and 1997
Both Melissococcus pluton (the EFB bacterium) and Thai Sac Brood Virus were detected from smear samples taken in Jumla, confirming the diagnosis of the diseases made on the basis of appearance of the brood.
In 1996, starving bees or bees with worker laying were more commonly found than diseases in colonies that were inspected. These could have been the final outcome of unmanaged disease, since they occur in queenless and / or weak colonies. Lack of feeding and other management practices may have been important in hastening death or absconding of colonies. Disease symptoms described complied with TSBV since larvae were being thrown out, absconding was heavy, larvae were rotten and smelling bad. The honey was sour or bitter in many cases and also was said to have had a bad effect on those who ate it.
The impact of brood diseases on bee populations in Jumla district between 1987 and 1997 was estimated by pooling farmer's responses to questions (in 1997) concerning numbers of bee colonies occupying hives and estimated annual honey yields for the preceding 2, 5 and 10 years (Figure 1.). Numbers of occupied beehives fell dramatically between 1992 and 1996, but increased again slightly in 1996-7. Numbers of colonies did not appear to increase in the year of the survey (1997), but this may have been because the entire season's crop of swarms could not be estimated at the time of sampling. Similarly, honey had not been harvested by many of the farmers in 1997 (only 56 farmers) at the time of the survey, so yields may be misleadingly small. Nevertheless a steady decline in honey yields is suggested between 1987 and 1997. This may be mainly due to brood disease, but depletion of forage resources and bee nesting habitat may also have had a negative impact.
Many farmers remembered the first TBSV epidemic, struck Jumla around 1983-1984 but may have started as early as 1978, and some claimed that the recent epidemic was equally as devastating. The main symptoms of brood disease observed by farmers were: slowed activity at the hive entrance; larvae (likened to cooked rice grains) being carried out of the hive; the bees becoming black and more defensive (due to few young bees surviving); sour or bad smells coming from the hive; and inactive bees clinging to each other inside hives. Perceptions as to the cause of the disease varied. Some farmers blamed infection on 'pollution' of hives from the touch of menstruating women or 'untouchable' (occupational caste) people! Others associated it with the introduction of apples and peaches into the district by the District Agricultural Development Office. This may be because the first TSBV epidemic coincided with the introduction of apples but it may also be associated with the introduction of pesticide usage that accompanied agricultural developments. Others directly blamed insecticides.
Information gathered suggested that indigenous hive baiting practices might also be responsible for rapid spread of brood diseases in traditional hives. Combs from absconded or dead colonies traditionally are kept aside for production of hive bait locally known as "ghosard". This is made from old combs beaten together in a pestle and mortar with honey and certain scented herbs. Combs with dried scales of dead larvae infected with TSBV and EFB become mixed into this mixture and probably inoculate the disease organism into baited hives. Extension workers tried to persuade farmers to dry-fry the combs thoroughly before they mixed them into 'ghosard' and to use combs from non-infected colonies in preference to combs from dead or absconded colonies. By providing training in beeswax processing to make candles and medicinal skin creams, and by buying beeswax from farmers for a processing and value addition enterprise in Jumla bazaar, combs from infected colonies were put to use and removed as a source of re-infection. Though farmers sold wax and used it to make creams and candles after receiving training, few accepted the practice of scorching inside their hives or of changing their method of making 'ghosard'.
Some farmers claimed that scorching their hives in the spring of 1998 caused a lack of swarms to be captured later in the season. They said that the comb imprints from previous years attract swarms and that if these are removed by scorching the smell of the hive becomes unattractive to bees. It was impossible to tell whether the low levels of occupation by swarms in 1998 was due to the scorching practice or the decline in populations of wild bees as a result of the 1997 disease epidemic.
Indigenous treatment of bee disease mainly involved smoking diseased colonies with Juniperus indica but various others herbs and organic material were also listed as smoking material by some farmers. These included:
- fish eggs, Jurinea dolonmiaea ('Bhut khes'), wild sheep horn, roots of a forest spinach known as 'ruga sag', Verbascum thapsus ('Gune Pucchar'), rice husks;
- Saussurea gossypiphora ('nau mukhi bhut khes'), lichens or fungi locally known as 'dinkine cheau' and 'chuna jurro', a species locally called 'Gokhal dhoop', and Juniperus indica ('dhoopy');
- Swertia chirata (Pate Tito) / Swertia racemosa (Danthe Tito);
- Aconite spp. (beek);
- 'Chuna mullo' probably another Aconite sp;
The latter 4 smokes probably have a 'knock-out' effect on bees and their parasites.
Feeding of bees with buckwheat and honey 'candy' in winter, applying a concentrate of a red turnip locally known as 'koira' around the mouths of hives, feeding very old honey and concentrates of peaches or forest fruits of Pyrus pashia, and infusion of pine needles (Pinus wallichiana) in sugar syrup, were said to be medicinal to bees. Sprinkling cow urine onto hives with special herbs is said to cure pollution from menstruating women!
2 Results of Experiences with Different Disease Control Measures
Practical experiences of managing bees in Jumla in movable and fixed comb hives in project-managed and farmers' apiaries are summarised as follows.
Feeding with sugar and medicines
Three main medicines were found to be useful for treatment of brood diseases in Apis cerana in Jumla. EFB responded to all three treatments and TSBV to the herbal treatments only.
- 'Terramycin' (oxytetracycline) antibiotic powder (as recommended by Morse and Nowogrodzki 1990, Akratanakul 1987, etc.) mixed into sugar syrup in dosages of 60-65 mg per colony and fed on alternate days for a total of three times.
- Azadirachta indica (neem) oil mixed in sugar syrup at dosage of 2-3 drops per colony depending of the size of the colony. This is fed at least three times per colony on alternate days but may need to be fed for up to seven doses in total, depending on the severity of the infection. Care must be taken with dosages as high concentrations of neem oil will kill the bees feeding on the syrup.
- Ayurvedic (herbal) medicine formulated by Kaminee Vaidya of Tribhuvan University using the following measurements (for approx. 1/2 litre of water):
These should be boiled together for 5-10 minutes and the resulting decoction used to make sugar syrup for feeding colonies. If herbs were dried, less could be used but in the same proportions. Local varieties of all the plants except Melia and C. longa are found in Jumla and turmeric is used in cooking in every household. One local beekeeper tried Swertia chirata and / or Swertia recemosa (locally called Chiraiti or Pate Tito and Danthe Tito respectively) in place of Melia with positive results. Artemisia can be used instead rather than in addition to Melia also.
Although the antibiotic removed disease symptoms more rapidly than the herbal remedies it did not cure the EFB long term. Most colonies had to be treated repeatedly, suggesting that oxytetracycline masks symptoms rather than providing a long-term solution to EFB disease. With TSBV the antibiotic serves only to further weaken colonies. Herbal remedies had greater application because they supported the bees in resisting both TSBV and EFB. Also problems of residues in honey and of resistance occurring in the pathogens are lower with herbs in combination than with use of a single antibiotic. However, herbal treatments need to be fed for longer and were not able to arrest infections that were already very advanced.
Biotechnical disease control practices together with feeding were more effective than simply feeding with syrup (with or without medicine). Timely sugar feeding, so that colonies were not stressed, was more effective than treatment with medicines once infection had developed.
Biotechnical methods work on the basis of breaking the cycle of infection by removing diseased larvae and / or preventing new larvae from being available for infection (PHCC 1996). Removal of infected brood combs and giving new comb foundation to break the cycle of infection into new larvae was more effective than attempts to cage queens. Removal of all brood combs and transfer into a new sanitised hive (i.e. artificial absconding), though a good way to remove the infection usually caused absconding, especially when the hive site was changed. So, later on only the most infected brood combs were removed and only in most severe cases were the boxes changed. Siting of colonies was not changed after initial attempts at artificial absconding resulted in absconding of colonies. Re-queening colonies with strong young queens, coupled with sugar feeding would have been a preferred option (cf. Chinh 2000) had new queens been available, but colonies weakened by disease were not strong enough to rear queens and usually other queens were not available.
Experiences of managing Apis cerana cerana bee colonies in modified log top-bar and other hives suggest that empirical trials should be made of the efficacy of Neem and the Nepali ayurvedic herbal decoction for controlling TSBV and EFB. Also, the influence of indigenous practices of smoking bees with Juniperus indica and other herbs on all forms of bee disease needs investigation
Promotion of movable comb beekeeping using appropriate technology log top-bar hives and training in diagnosis and control of bee diseases is possible even with illiterate farmers of the remote Himalaya. Such approaches should be adopted wherever disease is severely effecting bee populations.
TSBV and EFB brood diseases were confirmed to be present in Jumla district and responsible for wide-scale death and absconding of colonies from traditional and 'improved' hives, especially between 1995 and 1998. Control measures taken were to train farmers:
- how to feed bees with sugar syrup and antibiotic and / or herbal medicines;
- in use of the Jumla Top-bar hives to allow for early detection of disease;
- use of biotechnical control measures (especially removal of infected combs); and
- in hive sanitation practices to reduce sources of re-infection.
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The authors would like to thank the following for their assistance with this work: Satananda Upadhaya, Karna Bir Sunar and Kaali Bahadur Thapa; Anirudha Nath Shukla; Rabi Lal Budha and all the other farmer trainers of the Himalayan Beekeepers Association Jumla; Ganesh Rokaya, Karma Budha, Narayan Prasad Acharya and Jora Singh Budha of Surya Social Service Society (4S) Jumla for assistance with conducting the disease surveys, farmer-led extension and training programmes on beekeeping, top-bar hive making and bee disease control. Jumla beekeepers for answering questions and participating in the participatory action research; Ms. Mahalaxmi Shrestha of The Beekeeping Shop, Kathmandu for identification of Melissococcus pluton and Dr. Otto Boeking for identification of Thai Sac Brood Virus in smear samples from Jumla; Karnali Technical School for providing office and apiary locations; ICIMOD for project management; Austroprojekt and the Government of Austria for funding the project and for employing the author from October 1996 to October 1999; DFID for employing the author from April 1995 to October 1996.