Biology Reference
In-Depth Information
2.3.1 Case Study of
Ceratina l avipes
Japanese researchers Shoichi Sakagami and Yasuo Maeta worked with
a small carpenter bee called
Ceratina l avipes.
Females excavate the
pithy centers of stems and then provision cells with loaves of pollen
mixed with nectar, beginning at the point farthest from the entrance.
At er completing a pollen loaf, the female lays an egg on it, seals the
cell, and begins foraging to provision the next cell.
Ceratina l avipes
females are solitary. Females guard the entrance of the nest from para-
sites and predators by plugging the entrance hole with their bodies.
Sakagami and Maeta forced pairs of females to nest together in cages by
restricting the number of twigs they could excavate. At er making at-
tempts with 178 females, the researchers were successful in getting only
i ve pairs to nest together. In each of these i ve cases, one female be-
came the primary egg layer and guarded the entrance, while the other
foraged. A division of labor emerged between what are normally two
solitary individuals.
2.3.2 Case Studies of
Pogonomyrmex spp.
Jennifer Fewell did a similar experiment with ant queens from the spe-
cies
Pogonomyrmex barbatus. P. barbatus
queens begin excavating a
nest in the sandy soils of southern Arizona soon at er they make their
dispersal l ights from the natal nest and mate. h ey shed their wings
and then begin digging. h ey initiate nests on their own. Studies of one
population in Arizona have been ongoing for more than 30 years with-
out a single observation of two queens inhabiting the same nest. h ere-
fore, they are strictly solitary in their nest-founding behavior. Fewell
placed 63 pairs of individually marked, new queens in glass vials con-
taining sand and observed their digging behavior (Figure 2.5). Nest
excavation took place in all vials. In most cases, there was a signii cant
dif erence in the amount of time the two queens forced to cohabit spent
digging. In other words, a digging division of labor emerged.
Fewell pretested 18 solitary
P. barbatu s
queens to determine their
propensity to dig. She then combined them in pairs, observed their
