Morphology of the European species of the aphid genus Eulachnus (Hemiptera: Aphididae: Lachninae) - A SEM comparative and integrative study

Intraspecific Variability in Trionymus aberrans Goux, 1938 (Hemiptera: Coccomorpha: Pseudococcidae) with Description of the Second-Instar Nymph

The morphological characteristics of adult females of Trionymus aberrans Goux, 1938 (Hemiptera: Coccomorpha: Pseudococcidae) collected from post-industrial wastelands and other habitats in Poland and other countries were studied. Distinctive morphological variations were observed in the specimens from post-industrial wastelands in Poland. Scanning electron micrographs of the morphological characters of T. aberrans are provided. The presence of unusual pores, each with four loculi, was demonstrated for the first time in a species of Pseudococcidae. The importance of introducing additional morphological characters into the species description is discussed. New data on the frequency and host preferences of T. aberrans are also provided. This research is the first long-term study on scale insect species in post-industrial wastelands. The second-instar nymph of T. aberrans is described and illustrated and the presence of translucent pores on the hind coxae of this developmental stage is reported for the first time.

Is Every Vein a Real Vein? Cross-Section of the Wing of Matsucoccus Pini (Insecta, Hemiptera, Coccoidea: Matsucoccidae)

Wings of Matsucoccus pini males were studied. Using light and scanning electron microscopes, both sides of the wing membrane, dorsal and ventral, were examined. The presence of only one vein in the common stem was confirmed by the cross-section, namely the radius. The elements regarded as subcostal and medial veins were not confirmed as veins. On the dorsal side of the wings, a cluster of campaniform sensilla is shown for the first time in the family Matsucoccidae, through SEM, and two additional sensilla were found on the ventral side. There was a lack of alar setae, microtrichia as well as pterostigma. This is the second cross-section of the wing among scale insects. We propose the following nomenclature for the wings in the family Matsucoccidae: subcostal thickening (sct), radius (R), median fold (med) and anal fold (af).

Combined stereomicroscope and SEM disentangle the fine morphology of the undescribed larva and puparium of the hoverfly Milesia crabroniformis (Fabricius, 1775) (Diptera: Syrphidae)

With over 80 species, Milesia Latreille, 1804 is a hoverfly genus (Diptera: Syrphidae) found in all continents except for Australia and the Antarctica. However, little is known about its life cycle and biology. The three Milesia species for which early stages are known have saproxylic larvae, suggesting that the larvae of all other Milesia species are also saproxylic. The early stages of the three Milesia species occurring in Europe are undescribed. Milesia crabroniformis (Fabricius, 1775), a mimic of the hornet Vespa crabro Linnaeus, 1758, is the largest hoverfly in Europe and is listed as Least Concern in the IUCN European Red List of Hoverflies. We here report the first early stages of Milesia ever found in Europe, describing them and their breeding sites. Larvae of M. crabroniformis were collected in water-filled tree holes of live chestnut trees (Castanea sativa Mill.) in Málaga, Southern Spain in 2020-2021. Various studies based on stereomicroscope and scanning electron microscopy (SEM) techniques have proven useful in diagnosing hoverfly early stages by observation of their fine morphology. Thus, these techniques were also used here to characterize the second (L2) and third (L3) stage larvae of M. crabroniformis, as well as the puparium. A Leica M205C binocular stereomicroscope and a Jeol JSM-ITH500HR SEM were used. The head skeleton and chaetotaxy of the L3 larva were described and illustrated. Adjustments to the diagnosis of the larvae of Milesia are proposed based on the number of hooks from the primary row of the main group of hooks. The new early stages are compared with those of other Milesia hoverflies, as well as with those of the sister group Spilomyia Meigen, 1803. The knowledge of the larval biology and breeding sites of saproxylic insects is useful for implementing forest management measures and species' conservation programs.

Ultrastructure of a Mechanoreceptor of the Trichoid Sensilla of the Insect Nabis rugosus: Stimulus-Transmitting and Bio-Sensory Architecture

This paper presents the ultrastructure morphology of Nabis rugosus trichoid sensilla using SEM and TEM data, along with a two-dimensional model of the trichoid sensilla developed in Amira software. The SEM images show the shape and scattering of the trichoid mechanosensilla over the N. rugosus flagellomere. The TEM images present the ultrastructural components, in which the hair rises from the socket via the joint membrane. The dendrite sheath is connected at the base of the hair shaft, surrounded by the lymph space and the socket septum. This dendrite sheath contains a tubular body with microtubules separated by the membrane (M) and granules (Gs). This study presents a model and simulation of the trichoid sensilla sensing mechanism, in which the hair deflects due to the application of external loading above it and presses the dendrite sheath attached to the hair base. The dendrite sheath is displaced by the applied force, transforming the transversal loading into a longitudinal deformation of the microtubules. Due to this longitudinal deformation, electric potential develops in the microtubule's core, and information is delivered to the brain through the axon. The sensilla's pivot point or point of rotation is presented, along with the relationship between the hair shaft length, the pivot point, and the electric potential distribution in the microtubules. This study's results can be used to develop ultra-sensitive, bioinspired sensors based on these ultrastructural components and their biomechanical studies.

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.

Psyttala horrida (Stål, 1865) (Hemiptera: Reduviidae: Reduviinae)-A Morphological Study of Eggs and Nymphs

In terms of body size, species of the genus Psyttala Stål, 1859, are the largest known representatives of the subfamily Reduviinae. Among the species belonging to this genus, Psyttala horrida (Stål, 1865) is the most popular, mainly because it is a laboratory breeding species. Individuals of this species were bred in the laboratory of the Zoology Team at the University of Silesia in Katowice, Poland. A description of the morphology of the nymphs and eggs is presented. In addition to descriptions, photos of the successive immature stages are provided and scanning electron microscopy (SEM) images are included to show morphological details and compare the developmental changes in subsequent stages.

Toxicity and synergistic activity of compounds from essential oils and their effect on detoxification enzymes against Planococcus lilacinus

Mealybug, Planococcus lilacinus Cockerell, is a primary surface-feeding insect pest of fruit and flowering plants and also transmits plant viruses, resulting in economic crop loss. Inappropriate and recurrent use of pesticides for mealybug control results in resistance building and deleterious effects on humans and the environment. Essential oils are the most excellent choice for insecticides. Insecticidal activities of pure compounds of essential oils against P. lilacinus are not reported. The present study aims to study the insecticidal activities of some pure active compounds and their binary mixture's action by topical application against P. lilacinus. Results showed that the pure compounds of L-limonene, β-myrcene, and ocimene revealed toxicity (each at LD₅₀ = 0.37 µg/insect) after 96 h. The binary mixtures of geraniol + L-menthol and L-limonene + geraniol exhibited synergistic effects (each at LD₅₀ = 0.03 µg/insect) after 96 h. The monoterpenes of ocimene and β-myrcene at the higher concentration of 5,000 ppm substantially inhibited the detoxification enzyme activities of AChE (0.93 and 0.78 mU/mg, respectively) and GST (2.19 and 7.29 nmol/min/ml, respectively) in P. lilacinus after 48 h. SEM analysis reported the significant anomalies on the morphology of abdominal cuticle, setae, and thoracic leg after 96-h treatment with ocimene at 1,250 ppm against P. lilacinus. Based on the results, the tested pure compounds and their combinations can be suggested for the control of mealybugs.

Polyphenism in Antennal Sensilla Among Different Adult Morphs of Nonhost-Alternating, Holocyclic Sitobion avenae (Hemiptera: Aphididae)

Aphids, mainly distributed in temperate zones, exhibit seasonal generation-alternating phenomena. Across the life cycle, different morphs are produced. Sitobion avenae (Fabricius 1775) is a major pest of wheat worldwide. To elucidate olfactory perception of morph-specific behavior across their life cycle, we investigated antennal sensilla among seven morphs using scanning electron microscopy. Trichoid, placoid, coeloconic, and campaniform sensilla were identified. Trichoid sensilla, big multiporous placoid sensilla (primary rhinarium), a group of sensilla (primary rhinaria), and campaniform sensilla showed similar distribution and resemblance among morphs, whereas small multiporous placoid sensilla (secondary rhinaria) exhibited obvious differences. Compared to apterous morphs, alate morphs possessed a greater abundance of secondary rhinaria, with the greatest found in males on antennal segments III-V. Alate virginoparae and alate sexuparae ranged from six to fourteen rhinaria on antennal segment III. Fundatrices, apterous virginoparae and apterous sexuparae only had one or two secondary rhinaria on antennal segment III while they disappeared in oviparae. Secondary rhinaria, lying in a cuticle cavity, are convex or concave in their central part. In males, both forms were present, with a greater proportion of convex form than that of the concave form. Fundatrices and virginoparae had the convex form while sexuparae had the concave form. Polyphenism of secondary rhinaria might suggest their association with the olfactory functions of morph-specific behavior. These results have improved our understanding of the adaptive evolution of the antennal sensilla in nonhost-alternating, holocyclic aphids.

Two new genera and species of the Gigantometopini (Hemiptera, Heteroptera, Miridae, Isometopinae) from Borneo with remarks on the distribution of the tribe

Two new genera, each represented by a single new species, Planicapitus luteus Taszakowski, Kim & Herczek, gen. et sp. nov. and Bruneimetopus simulans Taszakowski, Kim & Herczek, gen. et sp. nov., are described from Borneo. Detailed photographs of male habitus and genital structures are presented. The checklist with distributional records for all known taxa of Gigantometopini is also provided.

Teratological cases of the antennae in the family Aradidae (Hemiptera: Heteroptera)

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.

The reproductive system of the male and oviparous female of a model organism-the pea aphid, Acyrthosiphon pisum (Hemiptera, Aphididae)

The structure of the reproductive system of the sexual generation-males and oviparous females-of the pea aphid Acyrthosiphon pisum (Harris) (Hemiptera, Aphididae), a serious pest of cultivated plants of Fabaceae, was investigated. For the first time we describe the morphology, histology and ultrastructure of the reproductive system in both morphs of the sexual generation of aphids within one species, using light and fluorescent microscopy, as well as transmission and scanning electron microscopy. The results revealed that males have testes composed of three follicles fused by the upper ends of the vasa efferentia, the vasa deferentia run independently, the accessory glands are asymmetric and the ejaculatory duct shortened. Oviparous females have ovaries composed of seven ovarioles each. The lateral oviducts join to a short common oviduct connected with the unpaired spermatheca and paired accessory glands. Yolky eggs with an aggregation of symbiotic bacteria at the posterior pole are produced. Histologically, the components of genital tracts are broadly similar: the epithelial cells of the walls of the vasa deferentia and accessory glands of the male and oviparous female have secretory functions which correlate with the age of the studied morphs. We also found symbiotic bacteria within the vasa deferentia epithelial cells in males and within the cells of the lateral oviducts of females. Because the pea aphid is listed among the 14 species that are of the greatest economic importance, our results will be useful for managing aphid populations, protecting plants and ensuring global food security.

Sulawesimetopushenryi, a new genus and species of Isometopinae (Hemiptera, Heteroptera, Miridae) from Sulawesi

A new genus and species, Sulawesimetopushenryi Herczek, Gorczyca & Taszakowski, sp. n., are described from Sulawesi, Indonesia. Photographs of the male and female habitus and male genitalia are presented and a short comparison with morphologically similar genera is drawn.

Molecular data and species diagnosis in Essigella Del Guercio, 1909 (Sternorrhyncha, Aphididae, Lachninae)

Morphological and molecular data are used to describe three new species of Essigella (Sternorrhyncha: Aphididae: Lachninae): Essigelladomenechisp. n., Essigellagagnonaesp. n., and Essigellasorensenisp. n.; and to re-establish as valid Essigellapatchae Hottes, 1957, stat. n., until now considered a synonym of E.pini Wilson, 1919. The catalogue of Essigella species is updated. This study highlights the need and utility to use discreet DNA characters in aphid species diagnoses.

DNA barcoding and a precise morphological comparison revealed a cryptic species in the Nippolachnus piri complex (Hemiptera: Aphididae: Lachninae)

Nippolachnus is a small Palaearctic-Oriental genus of very characteristic aphids that live on the leaves of woody Rosaceae. One species, N. piri, has hitherto been regarded to be widely distributed and relatively polyphagous. Members of this genus are considered to be easy to recognize due to the absence of the ocular tubercle and triommatidia on the head. We conducted research on the morphology and generic characters of Nippolachnus piri complex using scanning electron microscopy (for the first time) and DNA barcoding. We analyzed N. piri populations on Pyrus and other plants (Eriobotrya, Rhaphiolepis and Sorbus) in Japan and the Republic of Korea. Specifically, a high genetic divergence value was found between the N. piri populations associated with different host plants. SEM investigation of the head capsule revealed that a triommatidium is present under the compound eye, despite their lack of an ocular tubercle. We propose Nippolachnus micromeli Shinji, 1924 stat. nov. as a cryptic species in the N. piri complex based on a morphological comparison, DNA barcoding and different host-plant associations. Illustrations and descriptions of studied species are given. Morphological keys to the apterae and alatae of all known species of the genus Nippolachnus are also provided.

A comparative morphological revision of the aphid genus Myzaphis van der Goot, 1913 (Insecta: Hemiptera: Aphididae) revealed a new genus and three new species

The aphid genus Myzaphis van der Goot, 1913 from the tribe Macrosiphini is revised to include eight species. Apterous and alate viviparous females, known fundatrices and known sexual morphs (oviparous females and males) of Myzaphis bucktoni, M. juchnevitschae, M. rosarum, M. tianshanica and M. turanica are re-described and illustrated. Lectotype and paralectotypes of Myzaphis bucktoni and M. turanica are designated. The status of M. komatsubarae nomen dubium is discussed. Myzaphis avariolosa is regarded as a species belonging to the genus Ericaphis. Three new species: M. oezdemirae Kanturski & Barjadze sp. nov., M. tuatayae Kanturski & Barjadze sp. nov. from Turkey and M. rezwanii Kanturski & Barjadze sp. nov. from Iran are described and illustrated. Myzaphis bucktoni is recorded from Portugal for the first time. Diagnosis of the genus Myzaphis van der Goot, 1913 is redefined and a new genus Richardsaphis Kanturski & Barjadze gen. nov. is erected with the type species R. canadensis (Richards) comb. nov. Richardsaphis is for the first time recorded from the USA and hitherto unknown oviparous female and alate male are described and illustrated. Original keys to species of the genus Myzaphis and aphid genera of the tribe Macrosiphini with 2-2-2 first tarsal chaetotaxy are also provided.

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.

The forewing of the Aphis fabae (Scopoli 1763) (Hemiptera, Sternorrhyncha): a morphological and histological study

Dorsal and ventral sides of the forewing of Aphis fabae (Scopoli 1763) (Sternorrhyncha, Hemiptera) were examined by scanning electron microscopy. Reinforcement elements on their surface as well as scale-like elements were described. Using histological methods, cross-sections of the material were done. They showed a two-layered membrane with a circular foramen inside. The course of veins and places of their bifurcation were followed. Common stem of radius (R), media (M), and cubitus anterior (CuA) veins were composed of separate tracheae, which ran separately at the beginning, then continued in a single tunnel, and finally disappeared. Nerves were not observed. Neither were tracheae visible on the further course of those veins. The presence of a devoid-of-trachea costal vein was confirmed. Under scanning electron microscope, convex reinforcements on dorsal side of the wing turned out to be more sclerotized parts of chitin, not giving a zigzag-like profile of the wing on sections. In this paper, we show for the first time a cross-section of a very delicate wing of an aphid representative.

The Bhutan Pine Aphid Pseudessigella brachychaeta Hille Ris Lambers (Hemiptera: Aphididae: Lachninae) From India Reveals the Hitherto Unknown Oviparous Female and Dwarfish Male

Mariusz Kanturski, Shahid Ali Akbar, and Colin Favret (2017) Here we describe the presence of the monotypic and poorly known aphid genus Pseudessigella Hille Ris Lambers (Hemiptera: Aphididae: Lachninae) in India. So far, the genus has only been known from Punjab, Pakistan. Representatives of P. brachychaeta Hille Ris Lambers were collected from Pinus wallichiana A.B. Jacks. in the Yousmarg region of the state of Jammu and Kashmir in India. Hitherto unknown oviparous females and dwarfish males, the latter reported in Eulachnini for the first time, are described and illustrated. The male's antennal sensilla and genitalic morphology are additionally studied and presented using Scanning Electron Microscopy. Notes on the biology, distribution, and previously overlooked generic features are given. We provide morphological identi cation keys to the genera of the tribe Eulachnini and to the species of aphid living on P. wallichiana.

The relationships within the Chaitophorinae and Drepanosiphinae (Hemiptera, Aphididae) inferred from molecular-based phylogeny and comprehensive morphological data

The Chaitophorinae is a bionomically diverse Holarctic subfamily of Aphididae. The current classification includes two tribes: the Chaitophorini associated with deciduous trees and shrubs, and Siphini that feed on monocotyledonous plants. We present the first phylogenetic hypothesis for the subfamily, based on molecular and morphological datasets. Molecular analyses were based on the mitochondrial gene cytochrome oxidase subunit I (COI) and the nuclear gene elongation factor-1α (EF-1α). Phylogenetic inferences were obtained individually on each of genes and joined alignments using Bayesian inference (BI) and Maximum likelihood (ML). In phylogenetic trees reconstructed on the basis of nuclear and mitochondrial genes as well as a morphological dataset, the monophyly of Siphini and the genus Chaitophorus was supported. Periphyllus forms independent lineages from Chaitophorus and Siphini. Within this genus two clades comprising European and Asiatic species, respectively, were indicated. Concerning relationships within the subfamily, EF-1α and joined COI and EF-1α genes analysis strongly supports the hypothesis that Chaitophorini do not form a monophyletic clade. Periphyllus is a sister group to a clade containing Chaitophorus and Siphini. The Asiatic unit of Periphyllus also includes Trichaitophorus koyaensis. The analysis of morphological dataset under equally weighted parsimony also supports the view that Chaitophorini is an artificial taxon, as Lambersaphis pruinosae and Pseudopterocomma hughi, both traditionally included in the Chaitophorini, formed independent lineages. COI analyses support consistent groups within the subfamily, but relationships between groups are poorly resolved. These analyses were extended to include the species of closely related and phylogenetically unstudied subfamily Drepanosiphinae, which produced congruent results. Genera Drepanosiphum and Depanaphis are monophyletic and sister. The position of Yamatocallis tokyoensis differs in the molecular and morphological analyses, i.e. it is either an independent lineage (EF-1α, COI, joined COI and EF-1α genes) or is nested inside this unit (morphology). Our data also support separation of Chaitophorinae from Drepanosiphinae.