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Figure 1: Male Xylocopa latipes (Creative commons: G. Bohne, Flickr)

Table of Contents


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1. Introduction

It is big. It is black. It is scary. These are just some phrases that a layperson will describe the largest bee in Singapore, the Tropical Carpenter Bee (Xylocopa latipes)

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. However,Xylocopaspecies have a shiny abdomen which differentiates them from theBombusspecies with hairy abdomen.

Xylocopa latipesshares many similarities withX. aestuansin terms of foraging, nesting and pollination behaviour—mostly covered by Ng Kai Yi in the species page 'Xylocopa aestuans'. Hence, this page would focus more on the other interaction that X. latipeshas with the environment. The page targets insect enthusiasts as well as students in the field of environmental biology and ecology.

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2. Diagnosis

Click here to link you to detailed labelling of the different body parts of a bee.

Due to its large size (largest bee in Singapore), Xylocopa latipes can be easily distinguished from the other carpenter bees found in Singapore. X. latipes is about the size of a 9 volt battery (Figure 2).

Figure 2: Size comparison between X. latipes and a 9V battery
© 2016 G. W. Yong

2.1. Female comparison

Although not taxonomically fair, but it is generally possible to distinguish the female carpenter bees of Singapore to 2 or 1 species based on thoracic hair colour alone (Table 3). But fair warning, this should only serves as a guide and has to be taken with a pinch of salt. For more detailed species delimitation based on morphology characters refer to section 2.2.

Table 3: All species of carpenter bees (female) in Singapore generally categorised by thoracic hair colour (Images: © 2016 S. X. Chui). Every scale bar length is 10mm.
Black

X. latipes

X. auripennis

Blue

X. caerulea

X. insularis

Yellow

X. flavonigrescens

X. aestuans

White

X. dejeanii


Orange

X. myops



2.2. Female Diagnosis

The real problem lies when trying to distinguish between X. latipes and X. auripennis because both species look very similar. However, X.latipes is generally larger in size than X. auripennis. Figure 4 presents the key to distinguish the Xylocopa species in Singapore:

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Figure 5a: Thorax of X. latipes showing acute declivity
© 2016 Y. G. Tan
Figure 5b: Thorax of X. auripennis showing the relatively flat declivity
© 2016 S. X. Chui


2.3. Male comparison

Like the female Xylocopas of Singapore, it is generally possible to distinguish the male carpenter bees based on their thoracic hair colour (Table 6).

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Figure 7a: Male X. latipes showing front white tarsi © 2016 Y. G. Tan
Scale bar length is 10mm
Figure 7b: White tarsus of Male X. latipes © 2016 S. X. Chui
Scale bar length is 1mm


2.4. Male Diagnosis

Presented in Figure 8 are additional morphological characteristics that describe X. latipes. This is to ensure precise delimitation of male X. latipes from the other Xylocopa species from Singapore.

Figure 8: Diagnostic description of male X. latipes (contributed by J. S. Ascher)


2.5. Male VS Female

The males have enlarged eyes which converges above the head (Figure 9b). This is unlike the female, whose eyes do not strongly converge towards the top of her head (Figure 9a). Additionally, the males also have the front white tarsus (Figure 7), which is absent in females.

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Figure 9a: Head of female X. latipes © 2016 S. X. Chui
Scale bar length is 1mm
Figure 9b: Head of male X. latipes © 2016 S. X. Chui
Scale bar length is 1mm


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3. Behaviour

3.1. Pollination

Xylocopa latipes diurnal species and is most active from about 8am to 11am in the morning (personal observation, 2016). It is also a generalist when it comes to floral resource use—and will frequent large flowers due to its large body size (Video 10). For more detailed description, click here to go to the 'X. aestuans' page.

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Video 10: X. latipes pollinating


3.2. Buzz pollination

Xylocopa latipes holds on to a flower, shivering its indirect flight muscles at specific frequencies

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Video 11: Buzz pollination explained

3.3. Nectar robbing

At times, Xylocopa latipes uses its proboscis to cut through the tubular bases of flowers to obtain nectar (Video 12). The plant is not pollinated in the process of nectar robbing, and this behaviour reduces the reward (nectar) for other legitimate pollinators who visits the flower

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Video 12: Nectar robbing explained


3.4. Mating

During mating the male X. latipes uses his mid legs to hold onto the female thorax, pressing her wings down in the process (J. S. Ascher, personal communication) (Figure 13). The male then uses its front tarsi with the elongated white hairs to cover the female compound eyes. If the female tries to move he would then stroke her eyes, calming her down. This is similar to other species of solitary bees, like leaf-cutter bees (family: Megachilidae) with similar structures on their front tarsi

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Figure 13a: Male of a Megachile species brushing the compound eyes
with his pale tarsus (arrow) during copulation (pending permission

Footnote Macro

Batra, S. W. T. (1978). Aggression, Territoriality, Mating and Nest Aggregation of Some Solitary Bees (Hymenoptera: Halictidae, Megachilidae, Colletidae, Anthophoridae). Journal Of The Kansas Entomological Society, 51(4), 547-559.

)

Figure 13b: Schematic drawing of the mating behaviour
(pending permission

Footnote Macro

Wittmann, D. & Blochtein, B. (1995). Why males of leafcutter bees hold the females' antennae with their front legs during mating. Apidologie, 26(3), 181-196.

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3.5. Nesting

Xylocopa latipes utilises wooden beams, logs or hollow bamboo to make their nest

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, as they weaken the structure. The male does not play a role in constructing or providing for the nest. For more detailed description, click here to go to the 'X. aestuans' page.

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4. Ecology

4.1. Mites community

Figure 14: Acarinarium of a bee (pending permission

Footnote Macro

Batra, S. W. T. (1977). Bees of India (Apoidea), their Behaviour, Management and a Key to the Genera. Oriental Insects, 11(3), 289-324.

)

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. However, these mites are not specific to Xylocopa latipes and can be found on other paleotropical Xylocopa species. These mites are found either living in the brood cells of the nest of the Xylocopa species or in the acarinarium (Figure 14) of the Xylocopa bees.

There are mites that act as negative selection pressure on the host as they either are kleptoparasites (Horstia virginica; steals food from host) or by killing off the host eggs or larvae possibly consuming it as a resource (Sennertia americana).

Not all the mites are considered to interfere with the development with the host, in fact it was postulated that there is a positive selection for one of the mite species Dinogamasus sp. This genus of mites, feeds on microorganisms that potentially harms the bee larvae and pupa.

There are other mites that have a commensal relationship with the host. One species (Tarsonemus platynopodae) is a fungivore which helps the host to rid fungi from the nest; other species (Cheletophyes sp.) preys on smaller mites.

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5. Distribution

5.1. Global

Xylocopa latipes is typically found in the eastern tropical region of the world (Figure 15). The specimen in Germany, Guatemala and Mexico (red pins) is most likely to be erroneous as X. latipes is an eastern tropical species

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Figure 15: Global distribution of X. latipes (with permission, Discover Life)


5.2. Local

Generally, X. latipes can be found throughout Singapore and on some islands around Singapore. Figure 16 below depicts the localities where X. latipes has been caught from. However, the map may not be complete as there might be unexplored places with X. latipes sightings.

Figure 16: Local distribution of X. latipes (Source: NUS Insect Diversity Lab)


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6. Taxonomy & Phylogeny

6.1. Taxonomic classification

kingdomAnimalia
PhylumArthropoda
ClassInsecta
OrderHymenoptera
SuperfamilyApoidea
FamilyApidae
TribeXylocopini
GenusXylocopa
SubgenusPlatynopoda
Species epithetlatipes

6.2. Validity of subgenus Platynopoda

Michener (2007) have synonymised the subgenus Platynopoda into the subgenus Mesotrichia Westwood, 1838. However, this is believed to be incorrect. Phylogenetic analysis has shown that the subgenus Mesotrichia is paraphyletic to the subgenus Platynopoda 

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. This is evident from morphological evidence. Modifications to the first pair of legs were present in males from Platynopoda, while the modification were on the second pair of legs in Mesotrichia. The non-overlaping and apomorphic modification, within their own lineage, suggest the presence of 2 separate but closely related lineages.

Hence, this evidence suggest that Platynopoda is a subgenera on its own. However, further comprehensive phylogenetic analysis is required to fully understand the status of these lineages.

6.3. Phylogeny

Leys et al. (2002) investigated which phylogenetic analysis is the most robust to compare between different subspecies of carpenter bees. The 3 phylogenetic analysis used in the study were maximum parsimony, maximum likelihood and Bayesian analysis. The linearised Bayesian tree (Figure 17c) has been proposed to be the most reliable for phylogenetic analysis

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. Hence, bootstrap values are more conservative and more appropriate as errors tat occur at random probability is always present in original sequences.
Presented in the same paper by Leys et al. (2002) is the maximum parsimony tree (Figure 17a) and maximum likelihood tree (Figure 17b) which might be a viable alternative to the linearised Bayesian tree. The common themes in all three trees are that the genus Xylocopa is further separated into 3 clades—Ethiopian (made up of African and Oriental clade), Xylocopa s. l. clade (geographically diverse group) and a American clade.
The 3 clade this is supported by all 3 trees just indicates that there were 3 common ancestors, 1 for each clade. These 3 common ancestors went through many speciation events to give the many subgenera seen in the trees. Additionally, based Figure 10c, the common ancestor for the Xylocopa S. I. clade begun to speciate first, followed by the common ancestor in the American clade and Ethiopian clade.

Perhaps, the common ancestor of all 3 clades was a global species very much like the Xylocopa S. I. clade. Then one of the individuals of the common ancestral species decided to nest and propagate within the new world (America) around 35 million years ago, and another decided to nest and propagate within the old world (Africa + Oriental) around 30 million years ago. This could possibly have given rise to reproductive isolation, and the common ancestral lineage began to split into 3 distinct lineages, producing the 3 clades that we see now.

On a side note, X. auripennis (other black Xylocopa species found in Singapore) is the representative for the subgenus Biluna, which was found to be basal to all the other subgenus with strong support from both the maximum parsimony and Bayesian analysis.

6.4. Type information

Type materialMale holotype
Type localityAnjouan island (Union of Cosmoros)
Type repositoryDrury collection (London Natural History Museum)
CollectorDru Drury
Year collected1773
Type First mentioned

D. Drury, 1773. Illustrations of natural history

Footnote Macro

Drury, D. (1773). Illustrations of natural history. Wherein are exhibited upwards of two hundred and twenty figures of exotic insects, according to their different genera; very few of which have hitherto been figured by any author, being engraved and coloured from nature, with the greatest accuracy, and under the author's own inspection, on fifty copper-plates. With a particular description of each insect: interspersed with remarks and reflections on the nature and properties of many of them. By D. Drury. To which is added, a translation into french. Vol. II. London: Printed for the author, and sold by B. White, at Horace's Head in Fleet-street. 1773.

Original nameApis latipes Drury, 1773
SynonymsApis gigas DeGeer, 1773; Mesotrichia latipes (Drury, 1773); Xylocopa (Koptortosoma) latipes (Drury, 1773);
Mesotrichia (Platynopoda) latipes (Drury, 1773); Xylocopa (Platynopoda) latipes (Drury, 1773);
Mesotrichia (Platynopoda) latipes basiloptera (Cockrell, 1917)

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, hence there is a high chance there might be a mistake in sorting or recording the locality.


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7. References

Display Footnotes Macro


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This page was authored by Tan Yong Guang

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