This review investigates ant–aphid mutualism (trophobiosis), in particular focusing on evolutionary processes in aphids resulting from this interaction. This broad literature review allows us to revise existing views on certain aspects of this mutualism and provide the first timeline of its possible development over a geological timescale. We propose a new classification of ant–aphid mutualism with respect to its ecological characteristics and present new explanations of the development of certain morphological structures of aphids as resulting from adaptation to a trophobiotic relationship with ants. In light of these findings, the presence of the so‐called ‘trophobiotic organ’ in all myrmecophilous aphids is questioned. We review various communication modes between aphids and mutualistic ants and the possible influence of this symbiosis on modifications of aphid life cycles. Recent evidence on the suspected role of endosymbiotic bacteria in the development of mutualism is discussed. Finally, we propose a first timeline of ant–aphid interactions leading to the development of particular adaptations of aphids to mutualism, from general interactions between diverging Aphidomorpha and ants in the late Mesozoic to more specific coevolution between the aphid tribe Fordini and the ant genus Lasius.

There are three types of relationships between aphids and ants: non-myrmecophilous, obligatory and facultatively myrmecophilous. The degree of involvement in this mutualism is believed to be corelated with morphological adaptations of perianal structures. In this manuscript, we analyzed the differences of these structures in obligatorily (18 species) and facultatively (10 species) myrmecophilous aphids. Scanning electron microscopy (SEM) and light stereoscopic microscopy (LSM) techniques were used for these studies. Comparison of structures showed no strict relationship between their morphology and the degree myrmecophily, with certain indication that the microsculpture of perianal cuticle may play role in protection of aphids against honeydew droplet in facultatively myrmecophilous aphids.

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Artur taszakowski * & natalia Kaszyca-taszakowska teratological cases of the antennae in the family Aradidae (Hemiptera: Heteroptera) are widely described for the first time. Four hundred seventy-six specimens of flat bugs were studied, and antennal malformations were found in 14 of them (2.94%) (belonging to eight species and three subfamilies: Aradinae, Aneurinae and Mezirinae). All of the teratologies were observed using optical microscopy; moreover, in order to determine any compensatory regeneration, selected cases were also studied using a scanning electron microscope. In almost all of the specimens, the successful regeneration of the sensory organs to various degrees was observed. Additional results were the discovery of a previously unrecognized type of sensillum in flat bugs-a campaniform sensillum as well as significant differences in the distribution of the sensilla depending on the systematic affiliation.

Among mutualistic relationships of aphids with other organisms, there are two that seem to be of major importance: trophobiosis with ants and endosymbiosis of bacteria. While the former is well studied, the latter is the subject of an increasing amount of research constantly revealing new aspects of this symbiosis. Here, we studied the possible influence of ant attendance on the composition of aphid microbiota on primary and secondary hosts exploited by the aphid genus Dysaphis. The microbiome of 44 samples representing 12 aphid species was studied using an Illumina HiSeq 4000 with the V3-V4 region of 16S rRNA. The results showed a higher abundance of common facultative symbionts (Serratia, Regiella, Fukatsuia) in aphid species unattended by ants, but also on secondary hosts. However, in colonies attended by ants, the general species composition of bacterial symbionts was more rich in genera than in unattended colonies (Wolbachia, Gilliamella, Spiroplasma, Sphingomonas, Pelomonas). The results indicate a huge variability of facultative symbionts without clear correlation with ant attendance or aphid species. The possibility of multiple routes of bacterial infection mediated by ant-made environmental conditions is discussed.