1983] 
Frolich & Parker — Eumegachile 
207 
more than one egg per provision, makes partitions and plugs com- 
posed of leaf pulp and two layers of small compressed leaflets with 
no soil or pebbles, and constructs no vestibular or intercalary cells. 
No other biologies in the subgenus Sayapis are known and no biol- 
ogies or nest architectures are known in the other subgenera of 
Eumegachile. 
The manner in which E. pugnata constructs individual cells rend- 
ers its adoption as a potential pollinator of commercial sunflower 
somewhat problematical under certain circumstances. Eumegachile 
pugnata construct cells that are separated from each other by parti- 
tions and are not surrounded by a leaf envelope. This is unfortunate 
because E. pugnata is susceptible to a chalkbrood fungus, Ascos- 
phaera aggregata Skou, the treatment of which in other bees takes 
advantage of nest architecture. The disease sometimes decimates 
populations of the alfalfa leafcutting bee. Megachile rotundata 
(Fabricius), which construct cells that are completely leaf lined. 
During treatment, nests are opened, individual cells are separated as 
discrete leaf lined units, treated, and stored (Parker and Torchio 
1980). When M. rotundata emerge only egress from individual cells 
is necessary and adults are not required to chew through cells con- 
taining dead larvae with infectious spores. Since E. pugnata are 
protected only by a thin cocoon and no leaf lined envelope, removal 
from the nest would cause excessive mortality. This “loose cell” 
management is also used to control various M. rotundata parasites. 
In the case of E. pugnata parasites could emerge from individual 
cells and reparasitize other cells without leaving the nest. 
A second point that will have to be considered in commercial 
pollination is the fact that E. pugnata incorporates a fair amount of 
nectar into the provision. If growers are going to increase bee popu- 
lations, sunflower cultivars that provide adequate nectar will have 
to be available. 
Finally, one trait that makes E. pugnata a good candidate for 
sunflower pollination is its habit of provisioning cells early in the 
day. Male fertile sunflower cultivars dehisce overnight and in the 
early morning. Thus, the greatest amount of pollen is available 
during the time that E. pugnata are provisioning and pollinating 
flowers. 
