Nesting cavity diameter influences Megachile rotundata development, and may be true for other cavity nesting bee species

Last update: 30 December 2023

NEWS: 2023-XI-16 Journal of Economic Entomology
Nesting cavity diameter has implications for management of the alfalfa leafcutting bee (Hymenoptera: Megachilidae)

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.


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