Perianal Structures in Non-Myrmecophilous Aphids (Hemiptera, Aphididae).

Mutualistic relation with ants is one of the leading features of aphid ecology. For some aphid species, it is a crucial association enhancing their survival capability, while the life mode of some others is completely independent of ants. It was broadly accepted that during the evolution of aphids, the ones relying on ants developed special morphological adaptations for this mutualism, the so-called trophobiotic organ. Its exact structuring, however, posed some explanatory difficulties because many non-myrmecophilous aphids had structural modifications accordant with the trophobiotic organ, while some myrmecophilous did not. Here we present an evaluation of the morphology of perianal structures in 25 non-myrmecophilous aphid species with reference to previous, similar studies on myrmecophilous species based on scanning electron microscopy. We conclude that the trophobiotic organ is an existing adaptation, but its definition requires revision.

Microbiome of the Aphid Genus Dysaphis Börner (Hemiptera: Aphidinae) and Its Relation to Ant Attendance.

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.

Comparative Studies of Perianal Structures in Myrmecophilous Aphids (Hemiptera, Aphididae).

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.

Trophobiotic organ and perianal structures in aphid genus Stomaphis WALKER (Aphididae, Lachninae).

Stomaphis Walker is an obligatorily myrmecophilous, tree-trunk feeding aphid genus, having many peculiar features in its morphology. One poorly studied trait is its perianal anatomy, with suspected existence of trophobiotic organ and intriguing tubercles near abdominal segment VIII. Tubercles on rear end of abdomen in Stomaphis were considered to be marginal tubercles, structure typical of aphids. Only after their investigation under scanning electron microscope they revealed to possess a very rough surface, consisting of many protuberant, sclerotic scales with finger-like processes. Analysis and comparison with other aphids suggests, that these structures - perianal tubercles - may be considered remnants of abdominal sternite IX, atrophied in aphids. Due to their similarity to the surface of cauda of non myrmecophilous aphids, they are suspected to serve as sort of auxiliary caudas, protecting from sticky secretions of aphids e. g. honeydew or mucus while giving birth or ovipositing in confined space. A very well developed trophobiotic organ in this genus has been shown to exist for the first time.

Ant-induced evolutionary patterns in aphids.

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.

Morphological and histological study of the forewing of Orthezia urticae (Linnaeus, 1758) (Hemiptera, Sternorrhyncha).

Wings of Orthezia urticae males were studied. Both ventral and dorsal surfaces of wings were examined under light and scanning electron microscopes. The structure regarded as vein cubitus anterior turned out to be a reinforcement element only. Two elements known as radius sector and media are almost transparent depressions in the wing membrane. Veins at the margin of the fold of the wing anal lobe were not confirmed. Studies indicated a row of sensilla cupola at the beginning of the subcostal ridge. Cross sections of the wing membrane showed a two-layered membrane. The presence of two veins was confirmed in a common stem - subcostal and radius. The change of common stem shape was described. Neither tracheae nor nerves were observed. This is the second paper on cross-sections of wing within Sternorrhyncha.

Aphids Playing Possum - Defensive or Mutualistic Response?

Paper presents the phenomenon of thanatosis or death-feigning in selected aphids species. This specific reaction was predominantly analysed on the example of aphid subfamily Lachninae. Individuals of this group were used in experiments, during which a thanatotic response was induced with various results. The response differed from prolonged thanatosis, lasting for several minutes (Eulachnus rileyi), through shrinking behaviour (e. g. in Stomaphis graffii) to non-responsive species such as Cinara (Schizolachnus) pineti. The large interspecies variation of observed responses can be linked to other defensive mechanisms existing in the studied species, as well as to their mutualistic relationship with ants. The behaviour of shrinking is hypothesized to be the mutualistic response, developed from thanatosis, and being adapted to transportation by ant workers.

New records of an alien aphid species Tinocallis (Sappocallis) takachihoensis from countries in central and northern Europe (Hemiptera, Aphididae, Calaphidinae).

The aphid genus Tinocallis Matsumura, 1919 (Hemiptera: Aphididae: Calaphidinae) in central and northern Europe is reviewed; it includes four species. The first records of the Asian elm aphid Tinocallis takachihoensis Higuchi, 1972 are reported from the Czech Republic, Denmark, and Poland. The record in Denmark is the first in Scandinavia. Alate viviparous females and nymphs of T. takachihoensis were collected from Ulmus glabra "Pendula" (the Czech Republic and Poland) and from U. minor (Denmark) in 2017. Tinocallis takachihoensis is the fourth Tinocallis species to be recorded from Poland and together with two other species from the subgenus Sappocallis, T. nevskyi and T. saltans, is a species of alien origin. The alate viviparous females are reviewed and re-described and their affinities and distribution in central and northern Europe are discussed. A key to the European species of Tinocallis based on the characters of live and slide-mounted specimens is also given.

Sexual morphs of Pterocomma tremulae Börner, 1940 (Aphididae, Aphidinae) with description of male reproductive system.

Paper presents the first description of the so far unknown sexual generation of Pterocomma tremulae (Aphididae, Aphidinae): oviparous female and alate male. It also provides detailed description of the male reproductive system. Discussion focuses on comparative analysis of male reproductive system with other aphid groups and possible importance of its structure in resolving phylogenetic interrelationships within the genus Pterocomma. A key is provided to the known males of European Pterocomma species.

Perianal structures in myrmecophilous subterranean aphids (Insecta: Hemiptera: Aphididae) - Comparative morphology of trophobiotic organ with its first description in Lachninae.

Scanning electron microscopy (SEM) and light stereoscopic microscopy (LSM) were used for the first time to elucidate the external morphology of the so called "trophobiotic organ" on the end of abdomen of apterous viviparous females of six aphid species (Insecta: Hemiptera: Aphididae), representatives of the myrmecophilous, subterranean aphids from the subfamilies Anoeciinae (Anoecia furcata), Eriosomatinae (Forda formicaria, Geoica utricularia, Tetraneura ulmi), and Lachninae (Protrama flavescens, Trama troglodytes). We examined and compared the external morphology in the parthenogenetic generation living on roots of deciduous plants. FE-SEM images based on HMDS preparation techniques revealed great similarity of perianal structures even between not closely related groups. Rectangular, vertically positioned anal plate, extremely shortened cauda and setae around the anus seem to be common features of these aphids. However, some differences in the number and length of setae, their arrangement and inclination of anal plate may be observed. The discussion focuses on the adaptive importance of such modifications, with respect to underground life mode and myrmecophily, but with reservations concerning living in galls by representatives of Eriosomatinae, which is hypothesized to be a factor driving the development of such modifications of perianal structures in this group of aphids.

The structure of extremely long mouthparts in the aphid genus Stomaphis Walker (Hemiptera: Sternorrhyncha: Aphididae).

Scanning electron microscopy and light microscopy were used to elucidate the morphology of labium and mandibular and maxillary stylets of the aphids Stomaphis quercus (L.) and S. graffii Cholodkovsky. The mechanism of labium shortening associated with feeding process was described as well. Stomaphis quercus and S. graffii have cone-shaped labium of 13 and 10 mm in length, respectively, that strongly extend behind the abdomen. The stylets bundle comprises a pair of mandibular and maxillary stylets which are on average as long as labium. Serial cross sections of labium revealed that the first segment is inverted inside and the second is pulled into it; both segments are shifted into abdomen. This study provides new information on S. quercus and S. graffii mouthparts that may help to understand their feeding behavior.

Micromyzusplatycerii sp. n. (Hemiptera, Aphididae) - a new fern-feeding aphid species from Thailand.

A new fern-feeding aphid species, Micromyzusplatycerii, collected in Sakaerat Research Station in Thailand, is described.

Trigonocranus emmeae Fieber, 1876 (Hemiptera, Fulgoromorpha, Cixiidae) - a new species for Poland.

Single macropterous female of Trigonocranus emmeae Fieber, 1876 has been found during the faunistic studies in semi-natural plant communities of Oswiecim city in southern Poland. It is the first record of this species in Poland. Trigonocranus emmeae is rarely collected within the wide range of its distribution, mostly due to its hidden life mode.

Central European Acer- and Salicaceae-feeding aphids of the genus Stomaphis (Insecta: Aphidoidea: Lachnidae) -separate species or populations?

In Europe, there are three aphid species of the genus Stomaphis Walker that feed on trees in the genus Acer and one that feeds on trees in the family Salicaceae. Although these species are considered morphologically distinct, their uncertain host specificity and variation in morphological features has led to misidentifications or questionable attribution of subspecies status. The aim of the present study was to clarify the identity of the Central European representatives on the basis of morphological and molecular analyses. Our study is based on 42 samples from Central Europe and Northern Italy. Mitochondrial markers COXI and COXII were used to determine the molecular identity of the specimens studied. Our molecular analyses revealed the existence of three clades (two on Acer, one on Salicaceae) as defined by both molecular markers. Morphological analysis showed a broad range of variability of the key morphological features in all three clades. Despite significant differences in the mean values of morphometric traits, their range of variability strongly overlapped. Samples from COXI clades on Acer showed two different patterns of geographical distribution. Host specificity is recognized only at the level of host plant genera (Acer) and family (Salicaceae), excluding the possibility of the existence of separate subspecies on single host plant species.