Giant Jurassic dragon lacewing larvae with lacustrine palaeoecology represent the oldest fossil record of larval neuropterans.

Neuropterans seem to be less specious among holometabolans, while they are in fact the relicts of a diverse group from the Mesozoic era. Their early radiation resulted in great family level morphological heterogeneity of extant neuropterans, especially of their larvae. The earliest previously reported fossil larvae of this group were from the Early Cretaceous, where they already showed high taxonomic diversity and an extremely wide range of variations in morphotypes. In this work, the earliest record of the larva of the neuropteran Palaeoneurorthus baii gen. et sp. nov. from the Middle Jurassic Daohugou Beds of China is described. The larvae, which have large and elongated bodies, straight stylets with curved apices, an extremely elongated cervix and an extended anterior lobe of pronotum, are placed in Nevrorthidae. The elongated cervix is probably a specialized adaptation for hunting small organisms. The palaeoenvironment of these larvae indicates that larvae of Nevrorthidae have exhibited stable aquatic ecology since the Middle Jurassic, and underwent a possible shift from lakes to more lotic yet constricted modern mountain rivulet habitats over time.

Genomic regions underlying the species-specific mating songs of green lacewings.

Rapid species radiations provide insight into the process of speciation and diversification. The radiation of Chrysoperla carnea-group lacewings seems to be driven, at least in part, by their species-specific pre-mating vibrational duets. We associated genetic markers from across the genome with courtship song period in the offspring of a laboratory cross between Chrysoperla plorabunda and Chrysoperla adamsi, two species primarily differentiated by their mating songs. Two genomic regions were strongly associated with the song period phenotype. Large regions of chromosomes one and two were associated with song phenotype, as fewer recombination events occurred on these chromosomes relative to the other autosomes. Candidate genes were identified by functional annotation of proteins from the C. carnea reference genome. The majority of genes that are associated with vibrational courtship signals in other insects were found within QTL for lacewing song phenotype. Together these findings suggest that decreased recombination may be acting to keep together loci important to reproductive isolation between these species. Using wild-caught individuals from both species, we identified signals of genomic divergence across the genome. We identified several candidate genes both in song-associated regions and near divergence outliers including nonA, fruitless, paralytic, period, and doublesex. Together these findings bring us one step closer to identifying the genomic basis of a mating song trait critical to the maintenance of species boundaries in green lacewings.

Contribution to understanding the evolution of holometaboly: transformation of internal head structures during the metamorphosis in the green lacewing Chrysopa pallens (Neuroptera: Chrysopidae).

BACKGROUND: Metamorphosis remains one of the most complicated and poorly understood processes in insects. This is particularly so for the very dynamic transformations that take place within the pupal sheath of holometabolous insects. Only few studies address these transformations especially with regard to cranial structures of those holometabolous species where the larval and adult forms have a similar diet. It thus remains unclear to what extent the internal structures undergo histolysis and rebuilding. Here, the development of the brain and skeleto-muscular system of the head of Chrysopa pallens (Rambur, 1838) is studied. This species is a predator of aphids in the larval and adult stage. RESULTS: We used micro-computed-tomography (µ-CT) to study the transformations of the larval, prepupal and pupal head within the cocoon. We first assessed the morphological differences and similarities between the stages. We then determined the point in time when the compound eyes appear and describe the re-orientation of the head capsule which transforms the prognathous larva into a hypognathous adult. The internal head muscles are distinctly more slender in larvae than adults. In addition, the adults have a significantly larger brain which is likely needed for the processing of the signals obtained by the adults vastly expanded sensory organs that are presumably needed for dispersal and mating. Our study shows that the histolysis and modification of the inner muscles and skeletal elements take place within the prepupa. The central nervous system persists throughout metamorphosis but its morphology changes significantly. CONCLUSION: Our study reveals that not only the inner structures, but also the outer morphology continues to change after the final larval moult. The adult cuticle and internal structures form gradually within the cocoon. The histolysis and rebuilding begin with the skeletal elements and is followed by changes in the central nervous system before it concludes with modifications of the musculature. This order of events is likely ancestral for Holometabola because it is also known from Hymenoptera, Diptera, Mecoptera, and Coleoptera.

An integrative phylogenomic approach to elucidate the evolutionary history and divergence times of Neuropterida (Insecta: Holometabola).

BACKGROUND: The latest advancements in DNA sequencing technologies have facilitated the resolution of the phylogeny of insects, yet parts of the tree of Holometabola remain unresolved. The phylogeny of Neuropterida has been extensively studied, but no strong consensus exists concerning the phylogenetic relationships within the order Neuroptera. Here, we assembled a novel transcriptomic dataset to address previously unresolved issues in the phylogeny of Neuropterida and to infer divergence times within the group. We tested the robustness of our phylogenetic estimates by comparing summary coalescent and concatenation-based phylogenetic approaches and by employing different quartet-based measures of phylogenomic incongruence, combined with data permutations. RESULTS: Our results suggest that the order Raphidioptera is sister to Neuroptera + Megaloptera. Coniopterygidae is inferred as sister to all remaining neuropteran families suggesting that larval cryptonephry could be a ground plan feature of Neuroptera. A clade that includes Nevrorthidae, Osmylidae, and Sisyridae (i.e. Osmyloidea) is inferred as sister to all other Neuroptera except Coniopterygidae, and Dilaridae is placed as sister to all remaining neuropteran families. Ithonidae is inferred as the sister group of monophyletic Myrmeleontiformia. The phylogenetic affinities of Chrysopidae and Hemerobiidae were dependent on the data type analyzed, and quartet-based analyses showed only weak support for the placement of Hemerobiidae as sister to Ithonidae + Myrmeleontiformia. Our molecular dating analyses suggest that most families of Neuropterida started to diversify in the Jurassic and our ancestral character state reconstructions suggest a primarily terrestrial environment of the larvae of Neuropterida and Neuroptera. CONCLUSION: Our extensive phylogenomic analyses consolidate several key aspects in the backbone phylogeny of Neuropterida, such as the basal placement of Coniopterygidae within Neuroptera and the monophyly of Osmyloidea. Furthermore, they provide new insights into the timing of diversification of Neuropterida. Despite the vast amount of analyzed molecular data, we found that certain nodes in the tree of Neuroptera are not robustly resolved. Therefore, we emphasize the importance of integrating the results of morphological analyses with those of sequence-based phylogenomics. We also suggest that comparative analyses of genomic meta-characters should be incorporated into future phylogenomic studies of Neuropterida.

Ultrasound avoidance by flying antlions (Myrmeleontidae).

The acoustic arms race between insectivorous bats and their invertebrate prey has led to the convergent evolution of ultrasound hearing in seven orders of nocturnal insects. Upon hearing the echolocation calls of an approaching bat, such insects take defensive action. Here, we document a previously unknown sense of ultrasound hearing and phonotactic flight behaviour in the neuropteran family Myrmeleontidae (antlions). The antlion Myrmeleon hyalinus was presented with sound pulses at ultrasonic frequencies used by echolocating bats and its response thresholds in tethered flight determined. Behaviours included abdominal twitches, wing flicks, brief pauses in flight and flight cessation. Such behaviours create erratic evasive flight manoeuvres in other eared insects, particularly mantids and lacewings. Antlions responded best to ultrasound between 60 and 80 kHz (75 dB peSPL at 80 kHz), showing response thresholds similar to those of the related lacewings (Neuroptera, Chrysopidae). Yet, at lower ultrasonic frequencies (20-50 kHz), antlions were far less sensitive than lacewings. Based on calculated response distances, we conclude that antlions respond only after having been detected by bats rather than using early evasive flights. We argue that the high response threshold for low-frequency ultrasound is adaptive for an insect that is mainly active close to and within vegetation, because a behavioural response to the lower ultrasonic frequencies used by high-flying bats would result in evasive action in the absence of actual predation risk.

Comparative life-history responses of lacewings to changes in temperature.

Insects play a crucial role in all ecosystems, and are increasingly exposed to higher in temperature extremes under climate change, which can have substantial effects on their abundances. However, the effects of temperature on changes in abundances or population fitness are filtered through differential responses of life-history components, such as survival, reproduction, and development, to their environment. Such differential responses, or trade-offs, have been widely studied in birds and mammals, but comparative studies on insects are largely lacking, limiting our understanding of key mechanisms that may buffer or exacerbate climate-change effects across insect species. Here, we performed a systematic literature review of the ecological studies of lacewings (Neuroptera), predatory insects that play a crucial role in ecosystem pest regulation, to investigate the impact of temperature on life cycle dynamics across species. We found quantitative information, linking stage-specific survival, development, and reproduction to temperature variation, for 62 species from 39 locations. We then performed a metanalysis calculating sensitives to temperature across life-history processes for all publications. We found that developmental times consistently decreased with temperature for all species. Survival and reproduction however showed a weaker response to temperature, and temperature sensitivities varied substantially among species. After controlling for the effect of temperature on life-history processes, the latter covaried consistently across two main axes of variation related to instar and pupae development, suggesting the presence of life-history trade-offs. Our work provides new information that can help generalize life-history responses of insects to temperature, which can then expand comparative demographic and climate-change research. We also discuss important remaining knowledge gaps, such as a better assessment of adult survival and diapause.

The Morphological Diversity of Dragon Lacewing Larvae (Nevrorthidae, Neuroptera) Changed More over Geological Time Scales Than Anticipated.

Nevrorthidae, the group of dragon lacewings, has often been considered a relic group. Today, dragon lacewings show a scattered distribution, with some species occurring in southern Europe, Japan, Australia, and one in China. The idea that this distribution is only a remnant of an originally larger distribution is further supported by fossils of the group preserved in ambers from the Baltic region (Eocene, ca. 35-40 MaBP) and Myanmar (Kachin amber, Cretaceous, ca. 100 MaBP). Larvae of the group are slender and elongated and live mostly in water. Yet, larvae are in fact very rare. So far, only slightly more than 30 larval specimens, counting all extant and fossil larvae, have been depicted in the literature. Here, we report numerous additional specimens, including extant larvae, but also fossil ones from Baltic and Kachin amber. Together with the already known ones, this sums up to over 100 specimens. We analysed quantitative aspects of the morphology of these larvae and compared them over time to identify changes in the diversity. Despite the enriched sample size, the data set is still unbalanced, with, for example, newly hatched larvae (several dozen specimens) only known from the Eocene. We expected little change in larval morphology over geological time, as indicated by earlier studies. However, on the contrary, we recognised morphologies present in fossils that are now extinct. This result is similar to those for other groups of lacewings which have a relic distribution today, as these have also suffered a loss in diversity in larval forms.

An Expanded View on the Morphological Diversity of Long-Nosed Antlion Larvae Further Supports a Decline of Silky Lacewings in the Past 100 Million Years.

Lacewings have been suggested to be a relict group. This means that the group of lacewings, Neuroptera, should have been more diverse in the past, which also applies to many ingroups of Neuroptera. Psychopsidae, the group of silky lacewings, is one of the ingroups of Neuroptera which is relatively species-poor in the modern fauna. Larvae of the group Psychopsidae, long-nosed antlions, can be easily identified as such in being larvae of antlion-like lacewings without teeth in their stylets (=compound structure of mandible and maxilla), with empodia (=attachment structures on legs) and with a prominent forward-protruding labrum. Therefore, such larvae can also be recognised in the fossil record. An earlier study demonstrated a decline in the morphological diversity of long-nosed antlion larvae over the past 100 million years. Here, we report several dozen new long-nosed antlion larvae and expand the earlier quantitative study. Our results further corroborate the decline of silky lacewings. Yet, a lack of an indication of saturation indicates that we have still not approached the original diversity of long-nosed antlions in the Cretaceous.

The genome sequence of the Black Spongefly, Sisyra nigra (Retzius, 1783).

We present a genome assembly from an individual female Sisyra nigra (the Black Spongefly; Arthropoda; Insecta; Neuroptera; Sisyridae). The genome sequence is 372.6 megabases in span. Most of the assembly is scaffolded into 7 chromosomal pseudomolecules, including the X sex chromosome. The mitochondrial genome has also been assembled and is 16.34 kilobases in length.

The Diversity of Aphidlion-like Larvae over the Last 130 Million Years.

Aphidlions are larvae of certain lacewings (Neuroptera), and more precisely larvae of the groups Chrysopidae, green lacewings, and Hemerobiidae, brown lacewings. The name 'aphidlion' originates from their ecological function as specialised predators of aphids. Accordingly, they also play an economic role as biological pest control. Aphidlions have, mostly, elongated spindle-shaped bodies, and similarly to most lacewing larvae they are equipped with a pair of venom-injecting stylets. Fossils interpreted as aphidlions are known to be preserved in amber from the Cretaceous (130 and 100 million years ago), the Eocene (about 35 million years ago) and the Miocene (about 15 million years ago) ages. In this study, new aphidlion-like larvae are reported from Cretaceous amber from Myanmar (about 100 million years old) and Eocene Baltic amber. The shapes of head and stylets were compared between the different time slices. With the newly described fossils and specimens from the literature, a total of 361 specimens could be included in the analysis: 70 specimens from the Cretaceous, 5 from the Eocene, 3 from the Miocene, 188 extant larvae of Chrysopidae, and 95 extant larvae of Hemerobiidae. The results indicate that the diversity of head shapes remains largely unchanged over time, yet there is a certain increase in the diversity of head shapes in the larvae of Hemerobiidae. In certain other groups of Neuroptera, a distinct decrease in the diversity of head shapes in larval stages was observed.