Osmia latreillei (Spinola 1806)

Osmia (Chalcosmia) latreillei (Spinola)

On 9 March, while on a collecting trip along the Suez Canal, I noted several females of latreillei nesting within abandoned borings of other insects inside wooden posts in a garden devoted to commercial flower growing at Ismailia. I captured two of the females for identification. On 3 April I revisited this site, found latreillei still nesting in the posts, and set out a number of empty borings. On 23 April I checked these borings and found that latreillei females had completed nests in one 4.8-mm (No. 151) and in four 6.4-mm borings (Nos. 252, 253, 264, 382) and were storing cells in two 4.8-mm (Nos. 152, 158) and two 6.4-mm borings (Nos. 265,381).

NEST ARCHITECTURE.—The single completed nest in a 4.8-mm boring contained five stored cells, an intercalary cell 30 mm long between cells 3 and 4, and lacked a vestibular cell. There was one completed cell and one partially stored cell in each of the other 4.8-mm borings; the mother bees had left empty spaces of 5 and 30 mm at the inner end of these borings. The seven completed cells were 7–14 mm long (mean 12); males were reared from three cells 12–14 mm long, and presumably would have developed in the other four cells. The closing plug in the completed nest was 0.5 mm thick, and the partitions capping the cells were 0.14–0.4 mm thick. Both the closing plugs and partitions were made of masticated leaf pulp which dried to form a tough, stiff septum.

There were no empty spaces at the inner end in the 6.4-mm borings. There were 3–7 stored cells (mean 5.5) in the four completed nests. One 6-celled nest (No. 253) had an intercalary cell 65 mm long between cells 5 and 6. One nest (No. 253) lacked a vestibular cell, and the other three had vestibular cells 75–107 mm long (mean 91); two of the cells were divided into two sections by transverse partitions of leaf pulp. There was only one completed cell in the two partially stored 6.4-mm borings. One cell from which a female was reared was 14 mm long. The other 22 cells were 8–13 mm long (mean 9); males were reared from 16 of them, having the same range and mean in length. The closing plugs were 4–7 mm thick (mean 5), and cell partitions were 0.14–0.4 mm thick. Usually the partitions and closing plugs were made of masticated leaf pulp, but one plug had a layer of mud sandwiched between two layers of leaf pulp, and another plug had some thin interspersed layers of wood-pulp fragments from the sides of the boring, and the outer end was plastered with a thin layer of mud.

LARVAL FOOD.—The pollen-nectar masses were rather dry and contained a lesser proportion of nectar than in nests of some other Osmia. The pollen-nectar masses in male cells in 4.8-mm borings were 4–10 mm long (mean 6.6), and 3.5–7 mm long (mean 5.4) in male cells in 6.4-mm borings.

In six nests the bees stored pollen of Compositae, probably Dahlia. Pollen of a species of Rosaceae was stored in another nest. In the remaining two nests the bees stored pollen from still a third family of plants.

LIFE HISTORY.—Larvae had hatched in all of the completed cells when I opened the nests on 26 April, three days after gathering the nests. Egg hatch probably occurred only a day or two earlier in several of the cells in incompleted nests. The larval feeding period apparently lasted 20–25 days; larvae in these nests completed feeding 11–20 May. Newly hatched larvae fed for about 3–4 days before beginning to void fecal pellets; 10 days later the larvae began to spin these fecal pellets into a silken net against the anterior end and walls of the cell; feeding was completed in another 5–10 days.

Spinning of the cocoon required more than a day. The single female cocoon is 9 mm long; 18 male cocoons are 7–9 mm long (mean 8). The cocoon is ovoid in shape and slightly narrower than the diameter of the boring. It is composed of several layers of silk, the outermost being a loose network of fine white fibers attaching the inner cocoon to the cell wall. Beneath this is a thin layer of unvarnished white silk which can be readily peeled from the innermost layer of tough, brown varnished silk. At the anterior end there is a small cap composed of several layers of dense white silk which covers the nipple of the cocoon. The nipple is a rounded protuberance about 0.6 mm thick and 1.2 mm wide; it is composed of about four layers of coarse, reddish silk fibers.

After spinning the cocoon the larvae began a prolonged period of diapause which lasted variable lengths of time. In 6-celled nest 253 the male in cell 3 pupated before 16 August and eclosed as an adult the first week in September; I removed it from the cocoon in mid-October. (Males in cells 1, 4, 5, and 6 of this nest pupated in June the following year.) In nest 264 three males pupated about 1 September and eclosed as adults about 1 October; I removed them from the cocoons in mid-October.

No pupation occurred in the other nests by mid-October, so I put all of them outdoors in Arlington, Virginia, for a month to expose them to cooler but not freezing temperatures in an attempt to break the larval diapause. I brought them into my office in mid-November where they were kept at a temperature of 70° F. The prepupae continued to wriggle about actively when I examined the nests periodically, but pupation did not begin until mid-May 1966; pupation continued at intervals until 29 June. Newly eclosed pupae were entirely pale; the eyes turned pink four days later, dark brown after another three days, and black a day later; the rest of the body darkened gradually during the next 18 days. Periods of 25–31 days (mean 27) elapsed between pupation and eclosion of the adult. These adults remained in their cocoons for as long as two months before I removed and killed them.

The North American Osmia are vernal species which do not have a prolonged larval diapause. In pumila Cresson, for example, pupation occurs about 16–21 days after the larvae complete feeding, and the adults eclose in a month or less (Krombein, 1967, pp. 312–318). The adults remain in their cocoons for the remainder of the summer, autumn, and winter; they emerge from the nests early in the spring. It will be of interest to ascertain the developmental cycle of latreillei under normal conditions in Egypt. The data from these traps are possibly not typical because they were subjected to other than normal temperatures after 29 May 1965. Also, the sex ratio (1 ♀ : 19 ♂) is undoubtedly abnormal; many more females would probably have been obtained had the traps been set out when nesting began.

PARASITES.—The cuckoo wasp Chrysura pustulosa (Abeille) is probably a social parasite of latreillei. I captured a female of pustulosa on 9 March alighting on the same wooden post in which latreillei was nesting. I found a small, recently hatched chrysidid larva in one cell in each of three nests (Nos. 151, 252, 253) when I opened the latreillei nests on 26 April. These were bristly, fish-tailed larvae very similar in appearance to those of the North American Chrysura kyrae Krombein, which parasitizes Osmia lignaria Say (Krombein, 1967, pp. 444–445, figs. 87, 88, 128–130).

Chrysura larvae hatch several days later than the host bee larva, attach by their mandibles to the host bee, and suck a small amount of blood. They do not increase much in size, nor do they molt until the host larva has completed feeding and spun its cocoon. Then the Chrysura larva molts to the second instar and feeds on the resting larva of the host. It spins its own cocoon inside that of the host, then pupates and transforms to an adult that same summer. It emerges from the cocoon the following spring concurrently with the host bees.

A chrysidid larva 1.6 mm long was just emerging from the egg shell in cell 3, nest 252, at 1300 hours on 26 April, several days after the host bee larva hatched. The chrysidid egg had been deposited on the bottom side of the pollen-nectar mass. By 1400 the chrysidid larva had attached by its mandibles to the host bee larva several segments behind the head. It was still attached four days later. Subsequently, a male bee developed in this cell. I presume that the chrysidid larva may have become detached at the time the host larva spun its cocoon and was devoured by it.

The small chrysidid larva in cell 3, nest 253, was loose on the floor of the cell on 26 April. It finally attached to the bee larva on 29 or 30 April, and I noted it on the bee larva as late as 9 May. A male bee eventually developed in this cell, however, and I suppose it may have killed the parasite at the time of cocooning.

There was a newly hatched chrysidid larva just emerging from the egg in cell 5, nest 151, on 26 April. This cuckoo wasp egg was laid on the upper side of the pollen-nectar mass. The parasite larva attached to the bee larva on 29 or 30 April. The bee larva had almost completed feeding on 11 May, and the chrysidid larva was still attached securely and had not increased much in size. When I next examined this cell on 16 August, I found a pale, dark-eyed chrysidid pupa in the cocoon. It was accidentally injured the next time I examined it and died subsequently. Development had proceeded far enough so that the pupa could be definitely identified as that of a species of Chrysura.

Chrysura pustulosa has been reared from several other species of megachilid bees. Trautmann (1927, p. 111) reared it at Nuremberg from Osmia adunca (Panzer) and O. aenea (Linnaeus), and mentions that Frey-Gessner had bred it also from adunca and from O. caementaria Gerstaecker. Stoeckhert (1933, pp. 200, 204) reported Osmia adunca, O. caementaria, and O. aenea as hosts in southwestern Germany. Linsenmaier (1959, p. 80) stated that Bytinski-Salz had reared pustulosa from nests of the mud-daubing megachilid bee, Chalicodoma muraria (Retzius) in Palestine. Mocsáry (1912) notes that it was reared from Osmia solskyi Morawitz by Chobaut and from O. melanogaster aterrima Morawitz by Ferton as well as from two other hosts mentioned above.

Osmia latreillei is a species of mason bee belonging to the family Megachilidae subfamily Megachilinae.

Osmia latreillei é uma espécie de insetos himenópteros, mais especificamente de abelhas pertencente à família Apidae.

A autoridade científica da espécie é Spinola, tendo sido descrita no ano de 1806.

Trata-se de uma espécie presente no território português.

Osmia latreillei är en biart som först beskrevs av Maximilian Spinola 1806. Osmia latreillei ingår i släktet murarbin och familjen buksamlarbin. Den förekommer framför allt i Syd- och Mellaneuropa.

Osmia latreillei là một loài Hymenoptera trong họ Megachilidae. Loài này được Spinola mô tả khoa học năm 1806.