Occurrence of sexual morphs in Trama troglodytes von Heyden, 1837 (Hemiptera, Aphididae)

Abstract

The root-feeding aphids of the tribe Tramini have been cited as a possible case of ancient apomixis, as there are no substantiated records in the literature of a functional bisexual generation, even in common and well-known European species. The karyotypic variation found in this group, involving considerable structural heterozygosity within species, also pointed to the decay of diploidy that would be an expected consequence of loss of sexuality and absence of meiosis. However, we have now found a small number of oviparae (mating females) and males in populations of the common species Trama troglodytes. Fertilized eggs were not obtained, but adult oviparae contained large, yolky eggs. The single adult male was apterous, small and blind, but had fully developed mouthparts and genitalia, and contained mature sperm. Both sexual morphs are described, and the karyotrypic variation is reassessed in the light of these findings. Occasional sexual reproduction is in concordance with recent molecular evidence that some recombination occurs in T. troglodytes and related species.

Keywords:

• Aphids Tramini Ancient Apomixis Cryptic Recombination