Nesting Biology and Immatures of the Oligolectic BeeTrachusa larreae(Apoidea: Megachilidae: Anthidiini)

Abstract

Herein we report on the nesting biology of ground-nesting Trachusa (Heteranthidium) larreae (Cockerell) from New Mexico and Arizona, an oligolege of creosote bush, Larrea tridentata (DC.) Coville (Zygophyllaceae). Nests are single, slanting, open burrows at the lower end of which are horizontal cells lined with resin collected from creosote bush, also the source of the orange, mealy-moist provisions. Eggs are placed on the surface of the provisions, and the first three instars remain in the same position as the eggs from which they hatched. The fourth instar separates its body from the provisions, and only the fifth (final larval) instar moves around the brood chamber while consuming remaining provisions and defecating prior to cocoon spinning. It is suggested that middorsal body tubercles and an integumental body vestiture of short setae and setiform spicules restricted to this instar are adaptations enabling the movement of the fifth instar not only of this species but possibly those of other Megachilinae, all of which have a body vestiture and presumably middorsal body tubercles.The cocoon is spun after most of the feces are voided. Like cocoons of many other Megachilidae, it bears a pronounced nipple at its anterior end. From its construction as well as by comparison with cocoons of other bee taxa, the nipple seems to serve a number of functions: it enables exchange between the interior air of the cocoon and the external ambient air; it screens out parasites and predators from attacking the cocoon inhabitant; and it probably regulates cell humidity.Eggs are briefly characterized, and three females each were found to have three ovarioles per ovary and to carry a single mature oocyte, which is classified as medium in Iwata and Sakagami's classification of egg/mature oocyte size relative to body size of female. The fifth instars (both preand postdefecating forms) are described and found similar to those of other Anthidiini.

Nest and Immatures of the South American Anthidiine BeeNotanthidium(Allanthidium)chilense(Urban) (Apoidea: Megachilidae)

“…Where on the larva's body does the vestiture occur? The study of the setae and spicules of Trachusa larreae (rozen and Hall, 2012) demonstrated the diversity and patterning of the distribution of these structures and hints at the possibility that variation in them from one taxon to the next might demonstrate phylogenetic relationships if better understood.…”

Nest Site Selection and Nesting Behavior of the BeeLithurgopsis apicalis(Megachilidae: Lithurginae)

“…In the cocoons of L. apicalis, the quantity of the white material seems considerably less abundant and conspicuous than in the cocoons of L. chrysurus and, as a result, cocoon fronts of L. chrysurus tend to be more opaque. The source of the white material is unknown, but since it appears well after the exine-laden feces have been voided, we wonder whether it may come from the Malpighian tubules, as suggest by a recent study of Trachusa larreae (Cockerell) (rozen and Hall, 2012).…”

Mature Larvae and Nesting Biologies of Bees Currently Assigned to the Osmiini (Apoidea: Megachilidae)

“…Recently it has been suggested that this feature in megachilids appears to be restricted to the last larval instar, for earlier instars rarely exhibit any vestiture (Rozen et al, 2010a;Rozen and Hall, 2012) (with a few well-documented exceptions, e.g., Rozen et al, 1978). Limited displays of body setae, however, have also been reported in last larval instars of a few nonmegachilid taxa such as Eremapis (Exomalpsini) (Rozen, 2011a) and Emphorini (Rozen, 2011b), both Apidae.…”