Corresponding author: Sarah Kathleen Gess ( email@example.com )
Academic editor: Jack Neff
© 2017 Sarah Kathleen Gess, Peter Alexander Roosenschoon.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation: Gess SK, Roosenschoon PA (2017) Notes on the nesting of three species of Megachilinae in the Dubai Desert Conservation Reserve, UAE. Journal of Hymenoptera Research 54: 43-56. https://doi.org/10.3897/jhr.54.11290
Some observations on the nesting of three species belonging to phylogenetically interesting lineages of Megachilinae are presented. Published knowledge of the nesting of these species, Megachile (Maximegachile) maxillosa Guérin-Méneville (Megachilini), Megachile (Eurymella) patellimana Spinola (Megachilini), and Pseudoheriades grandiceps Peters (currently assigned to the Osmiini), is fragmentary making the notes presented here a worthwhile addition. The brood cells of M. maxillosa and of P. grandiceps, constructed from a mixture of resin and sand, were positioned in pre-existing cavities, trap-nests, above ground. The cells of the former are equal in diameter to the boring and are constructed in linear series. Those of the latter are small ovoid and are grouped to form a cluster. Megachile patellimana was nesting in burrows in compacted sandy ground beneath a plant and in the banks of an irrigation furrow. At the former site a female was carrying a freshly cut leaf piece and at the latter another was carrying a cut length of narrow, tough, green plastic. The nest contained a group of identical lengths of plastic, clearly a substitute for leaves.
Megachilinae, nests, sand, resin, leaves, plastic, trap-nests
In 2015 a brief preliminary survey of the aculeate wasps and bees of the Dubai Desert Conservation Reserve in the United Arab Emirates was undertaken between 18 April and 4 May, at the end of spring, by Sarah Gess assisted by Peter Roosenschoon, Conservation Officer. The principal focus of the survey was flower visitation. The results of the flower visiting survey with accounts of the history, climate and vegetation of the DDCR and descriptions of the study sites have been published (
Disappointingly little nesting activity was observed during this brief preliminary survey. However, notes were made on the nesting of some species. Included were three species of Megachilinae, Megachile (Maximegachile) maxillosa Guérin-Méneville (four nests), Megachile (Eurymella) patellimana Spinola (two nests) and Pseudoheriades grandiceps Peters (one nest). As these three species represent phylogenetically interesting lineages of the megachiline bees and as the published knowledge of the nesting of these species is fragmentary these notes offer a useful addition.
As flower visiting was being targeted most of the sampling was undertaken using hand nets. At all sites plants in flower were sampled for flower visitors. In addition wasps and bees perching on plants, resting on the ground, cruising, nesting and visiting water were collected.
Bundles of trap-nests (Figs
The positions selected for the trap-nests were: A branch of a the small tree Calotropis procera (Aiton) W.T. Aiton (Apocynaceae: Asclepiadoideae) (Fig.
The trap nests were set out on 20 April 2105. Construction of nests within these trap-nests was monitored up until the end of April by SKG and PAR. After SKG’s departure PAR continued to observe the nests and, after each was completed, took in the trap-nest and taped a vial over the open end to receive the imagines when they emerged. After the emergence of the imagines the Perspex sheets were removed and the opened trap-nests and the imagines were sent to SKG to be housed in the Albany Museum.
1a, b Branches of Calotropis procera: a opening to boring b cut longitudinally to show a boring with at its base nest cells of a leaf cutting megachilid bee 2 Boring openings in the leaf bases of Phoenix dactylifera 3 C. procera tree outside the drip irrigation area at Tawi Ruwyyan with a bundle of trap-nests suspended from a branch 4 Tawi Ruwayyan, looking from the C. procera tree towards the drip irrigation area 5 Trap-nest bundle on trunk of Phoenix dactylifera in the date palm grove at the Camel Farm 6 Date palm grove at the Camel Farm.
In their phylogenetic analysis of the tribe Megachilini
Senegal, Namibia, Botswana, South Africa, Zimbabwe, Malawi, Kenya, Sudan, Ethiopia, Saudi Arabia, Yemen and the DDCR (
There are no records for flower visiting by Megachile maxillosa in the DDCR (
The only published mention of the nesting of the subgenus Maximegachile appears to be a comment by
Four nests of Megachile maxillosa were constructed in trap-nests. Two of these trap-nests, both of 12.7 mm bore were part of the bundle suspended from the branch of the Calotropis procera tree at Tawi Ruwayyan and two of 9.5 mm bore were part of the bundle attached near the base of a date palm at the Camel Farm.
The walls of the cells, the cell closures and the nest closure were constructed from a mixture of sand and resin. The average length of the cells is 26.4 mm (sample of 12 cells). In three of the nests the first cell was initiated in contact with the inner end of the boring and in the fourth, one of the two from the Camel Farm, the first cell was initiated 25 mm from the inner end beyond a nest of Pseudoheriades grandiceps (Fig.
In completed nests the opening of the boring had been sealed with a 3 mm thick plug of sand and resin in consistency similar to that of the cell walls and closures. The empty space, the vestibular cell, between the last cell and the closure varied from 12 to 40 mm. In one of the nests the vestibular cell had been divided into two and in another three compartments (Fig.
Nesting progress. At Tawi Ruwayyan on 23 April a female Megachile maxillosa was provisioning a newly constructed cell in one of the trap-nests (trap-nest 1). By 27 April this nest consisted of two completed and sealed provisioned cells. After the second cell had been completed a leaf-cutting megachilid had usurped the nest (Fig.
At the Camel Farm on 23 April Megachile maxillosa was provisioning a cell in trap-nest 4 (Fig.
When PAR inspected the nests in early April 2016 no imagines had emerged but by 11 May five females and four males had emerged (Figs
Provision. The provision was a bright yellow, moist mixture of pollen and nectar (Figs
The identity of the pollen was not established. In order not to damage the nests the Perspex sheets were not removed until after the imagines had emerged.
Cocoon. The cocoons were brown, smooth and papery on the inside and lightly covered with silk spinnings on the outside. Each cocoon occupied the inner two thirds of a cell, the outer third being closely packed with fecal pellets.
A bombyliid larva was found in nest 1, suggesting that it had been responsible for the failed cell.
The female of Megachile patellimana, like most species of Eurymella, has robust mandibles with particularly large and acute teeth, as also seen in the subgenus Creightonella. In Eutricharaea, in contrast, the female mandibles are mostly less robust and the teeth smaller.
Widely distributed in western Palaearctic, particularly in the Mediterranean, Asia Minor, Egypt and UAE, also south-western Africa, Sudan, Niger and Mozambique (
In the DDCR Megachile patellimana has been recorded from flowers of Apocynaceae: Asclepiadoideae, Leptadenia pyrotechnica; Asteraceae: Centaurea pseudosinaica Czerep.; Boraginaceae: Heliotropium kotschyi; Brassicaceae: Farsetia linearis Decne ex Boiss.; Fabaceae: Mimosoideae: Prosopis cineraria ; Fabaceae: Papilionoideae: Crotalaria aegyptiaca Benth.; Zygophyllaceae: Tribulus maropterus Boiss.(
In Namibia this species has been recorded from flowers of Crotalaria podocarpa DC (Papilionoideae) (
The only published mention of the nesting of Megachile patellimana appears to be the statement in
The only other observations on nesting by a species of the subgenus Eurymella seem to be those for Megachile bucephala (Fabricius) (as M. semifulva Friese, recently placed in synonymy with M. bucephala (Eardley, 2013); this synonymy requires confirmation given that
It therefore seems worth recording the fragmentary observations on the nesting of Megachile patellimana in the DDCR where it was observed to be nesting at Tawi Manana in burrows excavated in compacted sand beneath Heliotropium kotschyi plants and at the Camel Farm in burrows excavated in the compacted sand banks of an irrigation furrow. It was not clear whether the burrows had been originated by M. patellimana or were pre-existing.
At Tawi Manana a female was captured carrying a piece of cut green leaf (approx. length 10 mm and approx. width 5 mm) and at the Camel Farm a female was captured carrying into a burrow a piece of tough green plastic approximately 10 mm in length cut from a strip 2 mm wide and almost 1 mm in thickness (Fig.
The use of plastic by Megahile patellimana, though surprising, is supported by the observations of
It is clear that the flexible pieces cut from polyethylene bags by Megachile rotundata were successfully used to construct cells whereas it is seems unlikely that Megahile patellimana would have successfully constructed cells from the stiff, narrow strips of plastic that she was assembling within her nesting burrow.
Provision. As both the nesting females were captured carrying nesting materials their scopae were empty and as nesting was in an early stage no provision was obtained from the nests.
The phylogenetic position of the genus Pseudoheriades is debated. In a molecular phylogeny of the Osmiini (
Saudi Arabia, United Arab Emirates, Iran, Pakistan and India (
The only published information on nesting by Pseudoheriades appears to be a brief account of the nesting biology of P. moricei (Friese) (
Krombein described the construction of four nests of Pseudoheriades moricei in trap-nests positioned variously on a vine-covered summer-house, a trellis and the trunk of a casuarina tree in gardens at three sites in Egypt. The cells, of the same diameter as the borings, were in linear series. The partitions capping the cells, dividing vestibular cells, and the closure of the nest were of resin or resin mixed with tiny pebbles.
The nest of Pseudoheriades grandiceps described by Rozen and Praz is based on notes, nest fragments and cocoons pinned with adults from the UAE preserved at Logan, Utah. Their figures 64 and 65 show two adults, one a female pinned with a leaf covered nest cell and a male pinned with a petal covered nest cell from which they had emerged. It was recorded that cell partitions within the leaf covering and petal covering were constructed from resin. It was not clear whether the leaves and petals had been placed by the female P. grandiceps or whether, as suggested by Praz, the trap-nest had been previously occupied by a different megachilid. The use of a pre-existing cavity, and the use of resin are the only similarities with the nest from the DDCR.
The notes presented here on nesting by Pseudoheriades grandiceps in the DDCR provide the first detailed observations on nest structure for this species. The nest was constructed in a trap-nest of 9.5 mm bore, part of the bundle attached near the base of the trunk of a date palm at the Camel Farm. It consisted of a cluster of cells constructed from a mixture of sand and resin. The cells free from the walls of the boring were ovoid, approximately 6 mm in length and at the widest point 3.5 mm in width with the wall approximately 1 mm in thickness. Those constructed against the Perspex cover were incompletely constructed, the Perspex forming part of the cell wall (Fig.
That no leaves or petals formed part of the nests of either Pseudoheriades moricei described by Krombein nor that of P. grandiceps described in the present contribution confirms the suggestion that the leaves and petals present in the nest of P. grandiceps nest described by Rozen and Praz were present in the trap nest before the female P. grandiceps started her nesting activities and that she had constructed her cells within the walls of cells of another megachilid that had previously occupied the cavity. Furthermore that the cells, composing the nest of P. grandiceps here described, were in a boring of larger diameter than the cells and that the cells were not constructed in linear series but were grouped to form a cluster suggests that P. grandiceps may be found to nest in cavities other than straight borings.
Nesting progress. The first cell had been constructed by 27 April and by 2 May five cells had been constructed. Sometime later the boring was usurped for nesting by Megachile maxillosa (Fig.
Provision. The identity of the pollen used in provisioning was not established. In order not to damage the cells the Perspex sheet was not removed until after the imagines had emerged.
Three specimens of Zonitoschema iranica Kasab, 1959 (Meloidae) from Ras al-Khaymah in the United Arab Emirates were recorded as having been reared from a nest of Pseudoheriades grandiceps (
8 Trap-nest 2 of trap-nest bundle at Tawi Ruwayyan on 27 April 2015, showing Megachile maxillosa initiating a cell 9 Trap-nest 1 of trap-nest bundle at Tawi Ruwayyan on 27 April 2015, showing two closed cells of M. maxillosa followed by leaf pieces, presumed to be those of a leaf cutting Megachile sp. 10 Trap-nest 2 of trap-nest bundle at Tawi Ruwayyan on 28 April 2015, showing first cell being provisioned by the builder, M. maxillosa 11 Trap-nest 4 of trap-nest bundle at the Camel Farm on 27 April, showing one open cell being provisioned by M. maxillosa 12 Trap-nest 4 of trap-nest bundle at the Camel Farm on 28 April 2016, showing two closed provisioned cells with M. maxillosa initiating a third cell 13 Trap nest 3 of trap-nest bundle at the Camel Farm showing nest of Pseudoheriades grandiceps at inner end followed by three-celled nest of M. maxillosa 14 Trap-nest 4 of trap-nest bundle at the Camel Farm showing final seal of nest of M. maxillosa 15 M. maxillosa female imago (actual length approx. 22 mm) with open cocoon.
Megachile patellimana: female (actual length approx. 16 mm) with a leaf piece (green and fresh when collected) and female (actual length approx. 16 mm) with cut lengths of plastic, one from female and the rest from her nesting burrow.
17a–c Cells of Pseudoheriades grandiceps in trap-nest 3 of trap-nest bundle at the Camel Farm 18 Nest of P. grandiceps after emergence of imagines, visible trapped between their natal nest and a nest of Megachile maxillosa which usurped trap-nest 3 19 P. grandiceps, imago (actual approx.7mm) from nest.
The large genus Megachile (sensu
Furthermore, resin appears to be an important nesting material broadly in the Megachilinae. In addition to its use in the Megachilini, resin is used by members of three of the four nest-building groups of the tribe Anthidiini (
It is clear that further studies on the nesting biology of additional species of Megachilidae will add to a fuller understanding of their phylogeny.
Grateful thanks are expressed by Sarah Gess to the following people and organizations:
Greg Simkins, Manager of the DDCR, for his invitation to work in the DDCR, for having made available, Peter Roosenschoon, Conservation Officer, DDCR, as her co-worker, for having provided transport, accommodation, meals and laundry during her stay; Rhodes University for her airfare and travel insurance; Tamer Khafaga, Conservation Officer, DDCR, for assistance with plant determinations; Christophe Praz, University of Neuchâtel, Switzerland for determining specimens of Megachile maxillosa, M. patellimana and Pseudoheriades grandiceps, and for assistance with the literature search; Jerome Rozen for determining the bombyliid larva from nest 1; Jerome Rozen and Christophe Praz for their encouragement, for reading and commenting on an early version of the manuscript and for their helpful comments and suggestions; Christophe Praz, reviewer, and Jack Neff, subject editor, for their constructive comments and suggestions for the improvement of the manuscript as originally submitted; and Christophe Praz for assistance with the discussion of the results in the context of megachilid phylogeny and evolution.