Biosystematic studies on stingless bees (apidae: meliponini ) of Kerala
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Date
2018
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Department of Agricultural Entomology, College of Agriculture, Vellayani
Abstract
The study entitled “Biosystematic studies on stingless bees (Apidae:
Meliponini) of Kerala” was conducted during the year 2016-2018 at the
Department of Agricultural Entomology, College of Agriculture, Vellayani with
the objectives of studying the stingless bee diversity of Kerala and to document
their nest entrance architecture.
A total of 225 different colonies of stingless bees were sampled from all
districts of the state. The sampling altitude ranged from 8 m (Kakkanad,
Alappuzha district) to 1064 m (Pampadumpara, Idukki district) above mean sea
level.
Two new species (Tetragonula sp. nov. 1, and Tetragonula sp. nov. 2) of
stingless bees based on adult worker specimens are described and illustrated with
the help of photographs. They are compared morphologically and molecularly
with closely related species. Differences in morphology based on principal
component analysis and genetic analysis based on partial sequences of the
mitochondrial COI gene barcode region support the recognition of the two new
species.
Along with the description, an analysis of their phylogenetic relatedness is
provided. The genetic analysis reveals that, Tetragonula sp. nov. 1 is closely
related to the common species T. iridipennis whereas Tetragonula sp. nov. 2 is
distantly related. The inter-specific genetic variation observed between T.
iridipennis was in a range 9.02-9.93% and 19.49-20.76% for Tetragonula sp. nov.
1 and Tetragonula sp. nov. 2 respectively.
Out of various morphological characters observed, the number of hamuli
was found varying within the T. iridipennis colonies. The current study revealed
that, there is 10.54% variation in the number of hamuli among the 1651 number
of individual bees studied. The normal number of hamuli recorded in this species
is 5 on each wing but it varied from 4 to 6 on both wings and also exhibited
asymmetry between the left and right wings.
The nest entrances of stingless bees varied widely within the colonies of
Tetragonula spp. The variation of nest entrance between the genera Tetragonula
and Lisotrigona were more prominent. It was observed that, the nest entrance
shape of Tetragonula sp. nov. 1 was square whereas it was round in Tetragonula
sp. nov. 2. The most common form preferred by T. iridipennis was slit like
entrance over oval, heart, round, and arch shaped ones. Length of the nest
entrance mouth preferred by T. iridipennis was less than 2cm and the nest
entrance width was recorded in a range of 1-2 cm. Out of 54 feral colonies of the
T. iridipennis studied, 24 were located at a height less than 1m from the ground
level, 25 were located at a height of 1-2 m and 5 colonies were located more than
2 m above the ground.
Two stingless bee species. viz., T. iridipennis (Smith) and Lisotrigona
cacciae (Nurse) were the only records from Kerala before this study. The
discovery of two new species during the present study elevates the total stingless
bee fauna of Kerala from 2 to 4 species. As the number of hamuli shows 10.54 %
variation, this character should be relied upon with caution while distinguishing
species.
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