EMERGENCE MODEL FOR BLUE ORCHARD BEE (OSMIA LIGNARIA)

The blue orchard bee (Osmia lignaria propinqua Cresson) is indigenous to the western United States and is a highly efficient pollinating insect for fruit trees.
Behavior and management studies by Torchio have shown that the adult bee’s active stage lasts 4–6 weeks and coincides with blossoming of stone and pome fruit trees.
This solitary bee is required to collect pollen and nectar on every foraging trip in contrast to the honey bee and is active over a wider range of environmental conditions.
The bee readily accepts man-made nesting materials, and nests can be transported from orchard to orchard.

As the blue orchard bee collects 80–85% of its pollen from fruit trees when placed in an orchard environment, and as emergence appeared to coincide with fruit tree blossom development irrespective of bloom date, we theorized that bee emergence could be predicted by the phenological models developed for fruit trees.

During the winters of 1982–1983, 1983–1984 and 1984–1985 four wooden traps, each containing 25 nests of blue orchard bee adults, were placed within a standard U.S. Weather Service instrument shelter located in a mixed fruit orchard.
Ambient temperature of the instrument shelter and temperature inside the bee trap were monitored throughout the winter.

The male bees emerge over a period of several days, 7–28 days prior to the female, depending upon the temperature regime.
Male bee emergence was best approximated by the ‘Tilton’ apricot chill unit and ASYMCUR models.
The chilling requirements for blue orchard bee is approximately 720 chill units.
Following completion of chilling the male bees emerge over a range of 1400–2800 growing degree hour (base 4.0° C) accumulation.
Female bee activity was observed at approximately 3900 GDH.

I International Symposium on Computer Modelling in Fruit Research and Orchard Management

J.L. Anderson, E.A. Richardson, P.F. Torchio

https://doi.org/10.17660/ActaHortic.1986.184.11