Disease screening and antimicrobial activity of stingless bees (Heterotrigona itama Cockerell and Geniotrigona thoracica Smith) in Malaysia
Honeybees are vulnerable to diseases and pests. The presence of pests and diseases in honeybee colonies had caused the honey industry to face many difficulties in the past. Stingless bees are the alternative producer for honey production. The occurrence of honeybee diseases in stingless bees have...
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| Format: | Thesis |
| Language: | English |
| Published: |
2022
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/119416/ http://psasir.upm.edu.my/id/eprint/119416/1/119416.pdf |
| Summary: | Honeybees are vulnerable to diseases and pests. The presence of pests and
diseases in honeybee colonies had caused the honey industry to face many
difficulties in the past. Stingless bees are the alternative producer for honey
production. The occurrence of honeybee diseases in stingless bees have been
reported in oversea and the health status of stingless bees in Malaysia is
unknown. Thus, this was the first attempt in Malaysia to screen the health of
stingless bees to see if they were free from honeybee diseases. Adults of
Heterotrigona itama and Geniotrigona thoracica were collected from eight
different farms and tested negative to seven known honeybee diseases. During
the sampling, one G. thoracica colony at the Department of Plant Protection,
UPM was detected having white mycelia on its propolis, and another H. itama
colony at the Infoport Halal Hub, UPM was collapsed with white dust covered
on the propolis. Isolation of the fungi were done, and pure colonies were
obtained. The fungus isolated from the G. thoracica colony was confirmed as
Lasiodiplodia theobromae, while the fungus isolated from H. itama colony was
confirmed as Aspergillus caelatus by morphological and molecular identification.
A pathogenicity test was conducted using both the fungus species and last
instar larvae the stingless bees. The LC50 value of 9.16 x 103 conidia/μl was
recorded in H. itama larvae infected with L. theobromae. It was not pathogenic
to G. thoracica (22% mortality). When H. itama and G. thoracica were
inoculated with A. caelatus, 100% mortality was obtained in both stingless bee
species. The LC50 value were 7.58 x 103 conidia/μl for H. itama and 6.24 x 103
conidia/μl for G. thoracica. A. caelatus was confirmed pathogenic to both H.
itama and G. thoracica. Antimicrobial susceptibility test was carried out using
the hemolymph of the last instar larvae of H. itama to test against A. caelatus.
No inhibition was observed in the treatment with either induced or non-induced
hemolymph at the end of the broth microdilution assay. The positive control,
intraconazole, had recorded 70.23% inhibition. Again, A. caelatus was
confirmed very pathogenic to H. itama and the insect host immunity was able to
fight against A. caelatus. The antimicrobial susceptibility test was not carried on
G. thoracica with both fungus species and H. itama with L. theobromae as the
bee colonies were stolen during the Covid-19 pandemic. |
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