Research on the Alfalfa leafcutter bee (Megachile rotundata) shows the development of these in cavity nesting bees can be influenced by the diameter of the cavity:
- A diameter of eight to nine millimeters resulted in the largest specimens and largest survival ratio.
- A diameter of seven millimeters resulted in the most females.
- A diameter of five to six millimeters produced the most offspring, of which predominantly females.
- A diameter of five millimeters resulted in bees with similar size as those in six and seven diameter nests, but needed less provisions to do so.
- The research suggests bees from nests with a diameter of four to six millimeters can carry more weight per gram body mass than their larger conspecifics.
- A diameter of four millimeters yields the highest diapause rates.
- Bees from the nine millimeter nests were not larger than those from eight millimeter. Furthermore a different nesting architecture consisting of two parallel rows of nest cells was observed at that diameter.
I can imagine a female adopting this in here nesting strategy in order to produce offspring with different characteristics. Observations made on the bee hotels in our garden shows that a species can use multiple nesting diameters, not only in bees but in cavity nesting wasps as well.
M. rotundata occurs in the Netherlands and is currently classified as very rare.
JOURNAL OF ECONOMIC ENTOMOLOGY article source