Mechanical factors in the reproductive isolation of Thynninae (Hymenoptera, Tiphiidae)

Abstract

?Mechanical factors in the reproductive isolation of Thynninae (Hymenoptera, Tiphiidae)?

The sequence of premating mechanisms in the reproductive isolation of four species of Thynninae (Elaphroptera scoliaeformis, E. atra, Anodontura tricolor, and Telephoromyia laeta) is studied in this paper. The following barriers are considered for the species involved: habitat isolation, olfactory stimuli and mechanical factors. Olfactory stimuli apparently play a double role as a locating and as an isolating mechanism; visual stimuli are important only to determine the exact position of females at a close range. In both species of Elaphroptera the male performs a very brief antennal tactile exploration of the female body; it was not possible to ascertain the role of this activity either as olfactory or as a mechanical recognition of female posture. The mechanical isolation is accomplished by the mandibular-prosternum grasping mechanism and by some special modifications of male mesosternum in relation to the metasoma of females; these modifications are highly specific and represent one of the most significant barriers in the reproductivo isolation of Thynninae.