Courtship behaviour in the genus Nomada – antennal grabbing and possible transfer of male secretions

Due to low population densities, copulation in the cuckoo bee genus Nomada has not previously been observed, although a seminal paper by Teng8 and Bergstrom (1977) on the chemomimesis between these parasitic bees and their Andrena or Melilla hosts postulated that secretions from male glands might be sprayed onto females during copulation. Our observations on the initiation and insertion phase of copulation in three species of Nomada now indicate antennal grabbing as a mechanism by which chemicals are transferred between the sexes. Histological studies of the antennae of N. fucata and N. lathburiana reveal antennal modifications associated with cell aggregations that represent glandular cells, and SEM studies revealed numerous excretory canals.