Megachile (Maximegachile) maxillosa

Gess, Sarah Kathleen & Roosenschoon, Peter Alexander, 2017, Notes on the nesting of three species of Megachilinae in the Dubai Desert Conservation Reserve, UAE, Journal of Hymenoptera Research 54, pp. 43-56 : 44-47

Megachile (Maximegachile) maxillosa

Taxonomy.

In their phylogenetic analysis of the tribe Megachilini Trunz et al. (2016) found that the subgenus Maximegachilae with the subgenus Neglectella formed a monophyletic group representing an isolated lineage.

Distribution.

Senegal, Namibia, Botswana, South Africa, Zimbabwe, Malawi, Kenya, Sudan, Ethiopia, Saudi Arabia, Yemen and the DDCR ( Gess and Roosenschoon 2016).

Flower visiting.

There are no records for flower visiting by Megachile maxillosa in the DDCR ( Gess and Roosenschoon 2016) nor as far as could be established are there any flower visiting records for this bee from elsewhere in the UAE. However, it has been commonly collected visiting flowers in the semi-arid to arid areas of South Africa and Namibia ( Gess and Gess 2003) where it was collected from flowers of Acanthaceae , Apocynaceae ( Asclepiadoideae ), Asteraceae , Brassicaceae , Fabaceae ( Caesalpinoideae , Mimosoideae and Papilionoideae ), Pedaliaceae and Polygalaceae , although in Namibia it was most commonly visiting Papilionoideae , most notably species of Crotalaria . No distinction was made between pollen collection and nectar uptake. Though clearly polyphagous, a preference for Fabaceae is suggested, possibly indicating some degree of specialization.

Nesting.

The only published mention of the nesting of the subgenus Maximegachile appears to be a comment by Kronenberg and Hefetz (1984, page 178) stating that " Megachile maxillosa nests in canes apparently without any further lining".

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. 7 , trap-nest 3).

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. 7 , trap-nests 3 and 1).

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. 9 ) and Megachile maxillosa had initiated cell construction in the neighbouring trap-nest (trap-nest 2) (Fig. 8 ). By the following day the walls of this cell had been completed and provisioning was in progress (Fig. 10 ). When taken in later during May the nest in trap-nest 2 had four completed cells and that in trap-nest 1 three completed cells, a large sub-divided vestibular cell and an outer seal, indicating that the usurper had been ousted (Fig. 7 , trap nest 1).

At the Camel Farm on 23 April Megachile maxillosa was provisioning a cell in trap-nest 4 (Fig. 11 ). By 28 April she had constructed, provisioned and sealed two cells and was busy constructing a third cell (Fig. 12 ). When inspected on 30 April there were 4 cells, all provisioned and closed. During May Megachile maxillosa had constructed, provisioned and sealed three cells in the neighbouring trap-nest 3 beyond a nest of Pseudoheriades grandiceps (Fig. 13 ). An empty vestibular cell had then been constructed subdividing the vestibular area between the last cell and the opening of the trap-nest, which had been sealed (Fig. 14 ).

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 7 , 15 ).

Provision. The provision was a bright yellow, moist mixture of pollen and nectar (Figs 9-12 ).

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.

Associated insects.

A bombyliid larva was found in nest 1, suggesting that it had been responsible for the failed cell.

Figures

Figure 7. Trap-nests 1 - 4 as at 25 May 2016 after Megachile maxillosa imagines had emerged from all of the cells. Trap-nest 3 shows the remains of the nest of Pseudoheriades grandiceps that preceded the nest of Megachile maxillosa.

Figures 8 - 15. 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 Megachile 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, Megachile maxillosa 11 Trap-nest 4 of trap-nest bundle at the Camel Farm on 27 April, showing one open cell being provisioned by Megachile maxillosa 12 Trap-nest 4 of trap-nest bundle at the Camel Farm on 28 April 2016, showing two closed provisioned cells with Megachile 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 Megachile maxillosa 14 Trap-nest 4 of trap-nest bundle at the Camel Farm showing final seal of nest of Megachile maxillosa 15 Megachile maxillosa female imago (actual length approx. 22 mm) with open cocoon.