Megachile (Callomegachile) sculpturalis Smith, 1853

Ivanov, S. P. & Fateryga, A. V., 2019, First record of the invasive giant resin bee Megachile (Callomegachile) sculpturalis Smith, 1853 (Hymenoptera: Megachilidae) in the Crimea, Far Eastern Entomologist 395, pp. 7-13 : 10-11

Megachile (Callomegachile) sculpturalis Smith, 1853

Figs 1–6

MATERIAL EXAMINED. Russia: Crimea : Simferopol, 44°56′13″N 34°08′07″E, dead in a lecture room, 2.IX 2019, 1 ♀ , S.P. Ivanov; ibid., dead under a bee hotel, 2.IX 2019, 3 ♀ ,

S.P. Ivanov; ibid ., exhausted after nesting finish, 6.IX 2019, 2 ♀, S.P. Ivanov [ CFUS]; ibid .,

natural death, 9.IX 2019, 1 ♀, S.P. Ivanov [ CAFK] .

DISTRIBUTION. China (including Taiwan), Korean Peninsula, Japan; introduced into

USA, Canada, Spain, France, Switzerland, Italy, Germany, Austria, Slovenia, Hungary (see references in the Introduction), and Russia (*new record).

BIONOMICS. Females of M. sculpturalis made their nests in paper tubes ( Fig. 2 ) and reed stems. One female observed on the morning of September 2 (from 8.15, solar time) was provisioning her nest while two other ones carried resin pellets with their mandibles. The resin was obviously taken from conifers as far as it had peculiar scent. Four species of conifers grew in the neighborhood of the balcony with the nests: Pinus nigra subsp. pallasiana (Lamb.)

Holmboe, P. brutia var. pityusa (Steven) Silba , Picea abies (L.) H. Karst. ( Pinaceae ), and

Platycladus orientalis (L.) Franco ( Cupressaceae ). It was impossible to establish which of them was used as the resin source. The resin was transparent and rather fluent. One of paper tube sheaves was nearly completely splashed with resin spread from just one nest plug.

The female provisioning her nest arrived each 20–25 min. in the morning and 30–45 min. in the evening. There was not much pollen in her scopa ( Fig. 2 ). Females were observed visiting inflorescences of Eryngium campestre ( Fig. 3 ), Inula helenium ( Fig. 4 ), and Carduus acanthoides while pollen samples taken from the foraging female at her nest contained only pollen of Ballota nigra . Low rate of foraging behavior was obviously associated with the age of the bees: all of them had substantially damaged wings ( Fig. 3 ). Forage recourses were also scarce due to the end of the season and the presence of competitive bee species such were

M. centuncularis ( Fig. 4 ) as well as Apis mellifera Linnaeus, 1758 (Apidae) and various sweat bees ( Halictidae ). Foraging flights were stopped at approximately 15.15.

Two dissected and studied nests were built in reed stems. The first one was dissected on

September 3, directly after it had been sealed by the female. It was located in a stem which was 26 cm in length and 10.2–11.3 mm in inner diameter. The nest itself occupied 8.5 cm of the stem length and contained three cells. The cells were built of resin with adding of mud at least to some elements of their structure. First cell was located directly at the bottom of the cavity; the second one was separated from it with a partition which was 1.2 mm thick in its center. The third cell was separated from the second one by much thicker partition consisted of three layers. Two outer layers were 1.5 mm thick each and made of resin and mud. A space between them was filled with mud with much less proportion of resin ( Fig. 5 ). Inner spaces of the cells were more or less ellipsoidal. Their sizes were 19.1×10.1, 19.0×10.2, and

18.0× 10.3 mm. The origin of the mud used as the building material was unclear. It was impossible to establish whether it was brought by M. sculpturalis female or remained from an old nest of any another bee species nested in this cavity earlier. Pollen loaf occupied less than a half of each nest cell volume. It had thick consistency and shining surface. The first and the second cells contained feeding larvae while the third one contained an egg ( Fig. 5 ).

The size of the egg was 5.6× 1.4 mm. Pollen loafs had distinctly different color in the second and the third cells. This difference was obviously caused by changing of a forage plant after provisioning of the second cell. All larvae finished their feeding and started cocooning by

October 1.

The second nest was dissected two weeks after it had been sealed by the female. It was located in a stem which was 28 cm in length and 14.4 mm in inner diameter. The nest itself occupied 4.7 cm of the stem and contained two cells. This nest also contained mud used as building material in addition to resin. Particularly, the mud was used for lateral walls of the cells where it was mixed not only with resin but with sawdust as well. These walls were up to

3 mm thick. The inner sizes of the cells were 24.9×10.6 and 19.6× 9.9 mm. The second cell was sealed with plug which was 2.6 mm thick in its center. The first cell contained a prepupa while the second one contained a false pollen loaf, a mass of pollen and nectar covering the cell wall by a 2–3 mm-thick layer, and no progeny ( Fig. 6 ).

Figures

Figs 1–6. Bionomics of Megachile sculpturalis Smith in the Crimea: 1 – “bee hotel”