MSc

The study entitled “Etiology of honey bee brood disease in Southern
Kerala” was conducted with the objective to characterize, identify and confirm the
infectivity of the microbial isolate from diseased Indian honey bee brood and also
to test the efficacy of botanicals against it. The study was carried out during the
period 2016-2018 at AICRP on Honey bees and Pollinators, Department of
Agricultural Entomology, College of Agriculture, Vellayani.
Survey was conducted in the Indian bee apiaries of three Southern
districts of Kerala viz. Thiruvananthapuram, Kollam and Pathanamthitta. From
each district, five apiaries with a minimum of 10 colonies were selected
purposively. The infected brood samples were subjected to laboratory study to
understand the etiology of the disease. Evaluation of botanicals against the Indian
bee brood disease using different botanicals was also conducted.
Scattered presence of sealed and unsealed brood giving “pepper-box
symptom”, change in colour of the larvae from pearly white to yellow and finally
dark brown, perforated brood cappings with dead pupae and infected larvae
transform into brown scales which were seen adhered to the bottom of the cell,
were the typical symptoms observed in the infected bee colonies. Apart from
these, the adult bees were found restless and more aggressive, reduced foraging
activity, tendency for absconding and reduced honey yield were also observed.
The monthly incidence of the disease varied among different locations
with the peak infection period during the dearth season (May to August) in
Thiruvananthapuram district, while in Kollam district it was observed in both
dearth season and brood rearing season (Sept. to Dec.). Among the three districts,
highest mean percentage infection was recorded from the apiaries of Kollam
district (44.36) followed by Thiruvananthapuram district (4.45) and the least
infection percentage from the apiaries of Pathanamthitta district (1.07).
Three bacterial colonies were isolated (viz. J1, J2 and J3 isolates) in the
nutrient agar (NA) medium from the infected brood samples taken during survey.
The bacterial isolates, J1 and J3 which were proved pathogenic to the honey bee
larvae
were
subjected
to
morphological,
molecular
and
biochemical
characterisation. The bacteria, identified as Bacillus pumilus and Achromobacter
sp., has already been reported to be associated with Melissococcus plutonius,
causal agent of European Foul Brood.
Evaluation of botanicals for the management of Indian bee brood disease
with crushed garlic (0.25 % and 0.5 %), crushed leaves of Centella asiatica (0.05
% and 0.1 %), crushed leaves of Ocimum sp. (0.05 % and 0.1 %), turmeric
powder (0.2 %), CaSO4 (homeo medicine), along with oxytetracycline
hydrochloride (antibiotic) (40 ppm) as check and a control provided with artificial
feed, was assessed in terms of infected brood area, sealed brood area, unsealed
brood area, pollen storage, honey storage and number of foragers per minute.
After four weeks of treatment, bee colonies treated with crushed garlic 0.25 % and
crushed leaves of Ocimum sp. 0.05 % recorded highest percentage reduction of
the disease with a mean value of 68.52 and 67.57 respectively.
Apart from these, a significant increase in sealed brood area (286.07 cm2
and 261.32 cm2), unsealed brood area (236.80 cm2 and 222.22 cm2), pollen
storage (49.19 cm2 and 47.70 cm2), honey storage (84.74 cm2 and 77.13 cm2) and
number of foragers (3.13 and 3 bees per minute) were also observed in the
colonies treated with crushed garlic 0.25 % and crushed leaves of Ocimum sp.
0.05 % respectively, when compared to their respective control (34.62 cm2;
124.71 cm2; 14.88 cm2; 39.68 cm2and 1.13 bees per minute).
Thus the present investigation revealed that the Indian bee apiaries of
Kollam district recorded the highest incidence of brood disease in southern Kerala
during the dearth and brood rearing season, with a mean percentage infection of
44.36 followed by Thiruvananthapuram district (4.45) and Pathanamthitta district
(1.07) Two bacterial isolates which proved the pathogenicity were identified as
Bacillus pumilus and Achromobacter sp. Crushed garlic 0.25 % and crushed
leaves of Ocimum sp 0.05 % were found effective in the field evaluation of
botanicals, against brood disease, with a mean percentage reduction of 68.52 and
67.57 respectively.
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