Effects of larval antlions Euroleon nostras (Neuroptera, Myrmeleontidae) and their pits on the escape-time of ants

Abstract. Pit-building antlions are predators with a unique predation strategy, namely using pitfall traps constructed in loose sand to catch prey. Here, prey escape-time in the field is measured by introducing ants into one of four different treatment arenas. The first treatment lacks pits and antlions, the second includes 10 antlions that did not build pits, the third comprises eight artificially constructed pits, and the fourth is a treatment of eight antlions in pits and two without pits. Their pits are of a similar size to those used in the third treatment. When antlions are present without constructing pits, they impede the dispersal of prey. The mean escape-time for one half of the released ants is twice as long with antlions present as without them. When pits are present, the time taken for one half of the released ants to escape the predator is more than 10 times as long as when pits are absent. Escape-time from artificial pits is three times that from nonpit building antlions. Pits hinder the escape of ants and therefore increase the amount of time that the prey is available for capture. In the area where the pits are occupied by antlions, escape-time is four times longer than in a treatment with similar sized artificial pits. Thus, it appears that not only a pit, but also the presence of antlions influences the capture success.     

New records and new synonyms of antlions (Neuroptera, Myrmeleontidae) from China

The antlions from the subfamilies Nemoleontinae and Myrmecaelurinae deposited in the Entomological Museum of the China Agricultural University (CAU) belong to 16 species, among which 11 are recorded for China for the first time. Four species with mostly Oriental distribution are recorded for the first time from the northern localities in Palaearctic China. The Dzungarian faunistic center of antlions with two species recently described from Turan is distinguished. Some species characteristic of Mongolia were found in adjacent China. Occurrence in China of three species, collected by Russian expeditions 100 years ago, is confirmed. Five species described by Yang from China have been synonymized with widely distributed species.     

Chromosome numbers in antlions (Myrmeleontidae) and owlflies (Ascalaphidae) (Insecta,Neuroptera)

A short review of main cytogenetic features of insects belonging to the sister neuropteran families Myrmeleontidae (antlions) and Ascalaphidae (owlflies) is presented, with a particular focus on their chromosome numbers and sex chromosome systems. Diploid male chromosome numbers are listed for 37 species, 21 genera from 9 subfamilies of the antlions as well as for seven species and five genera of the owlfly subfamily Ascalaphinae. The list includes data on five species whose karyotypes were studied in the present work. It is shown here that antlions and owlflies share a simple sex chromosome system XY/XX; a similar range of chromosome numbers, 2n = 14-26 and 2n = 18-22 respectively; and a peculiar distant pairing of sex chromosomes in male meiosis. Usually the karyotype is particularly stable within a genus but there are some exceptions in both families (in the genera Palpares and Libelloides respectively). The Myrmeleontidae and Ascalaphidae differ in their modal chromosome numbers. Most antlions exhibit 2n = 14 and 16, and Palparinae are the only subfamily characterized by higher numbers, 2n = 22, 24, and 26. The higher numbers, 2n = 20 and 22, are also found in owlflies. Since the Palparinae represent a basal phylogenetic lineage of the Myrmeleontidae, it is hypothesized that higher chromosome numbers are ancestral for antlions and were inherited from the common ancestor of Myrmeleontidae + Ascalaphidae. They were preserved in the Palparinae (Myrmeleontidae), but changed via chromosomal fusions toward lower numbers in other subfamilies.     

Sand as a medium for transmission of vibratory signals of prey in antlions Euroleon nostras (Neuroptera: Myrmeleontidae)

Abstract.  European pit-building antlions ( Euroleon nostras / Geoffroy in Fourcroy/) detect their prey by sensing the vibrations that prey generate during locomotory activity. The behavioural reactions and some of the physical properties of substrate vibrations in sand are measured to observe signal transmission through the substrate. The frequency range of the signals of four arthropod species ( Tenebrio molitor , Pyrrhocoris apterus , Formica sp. and Trachelipus rathkei ) is 0.1–4.5 kHz and acceleration values are in the range 400 μm s⁻² to 1.5 mm s⁻². Substrate particle size and the frequency of prey signals both influence the propagation properties of vibratory signals. The damping coefficient at a frequency 300 Hz varies from 0.26 to 2.61 dB cm⁻¹ and is inversely proportional to the size of the sand particle. The damping coefficient is positively correlated with the frequency of the pulses. Vibrations in finer sand are attenuated more strongly than in coarser sand and, consequently, an antlion detects its prey only at a short distance. The reaction distance is defined as the distance of the prey from the centre of the pit when the antlion begins tossing sand as a reaction to the presence of prey. The mean reaction distance is 3.3 cm in the finest sand (particle size ≤ 0.23 mm) and 12.3 cm in coarser sand (particle size 1–1.54 mm). The most convenient sands for prey detection are considered to be medium particle-sized sands.     

Owlflies are derived antlions: anchored phylogenomics supports a new phylogeny and classification of Myrmeleontidae (Neuroptera)

The first phylogenomic analysis of the antlions is presented, based on 325 genes captured using anchored hybrid enrichment. A concatenated matrix including 207 species of Myrmeleontoidea (170 Myrmeleontidae) was analysed under maximum likelihood and Bayesian inference. Both Myrmeleontidae (antlions) and Ascalaphidae (owlflies) were recovered as paraphyletic with respect to each other. The majority of the subfamilies traditionally assigned to both Myrmeleontidae and Ascalaphidae were also recovered as paraphyletic. By contrast, all traditional antlion tribes were recovered as monophyletic (except Brachynemurini), but most subtribes were found to be paraphyletic. When compared with the traditional classification of Myrmeleontidae, our results do not support the current taxonomy. Therefore, based on our phylogenomic results, we propose a new classification for the antlions, which synonymizes Ascalaphidae with Myrmeleontidae and divides the family into four subfamilies (Ascalaphinae, Myrmeleontinae, Dendroleontinae and Nemoleontinae) and 17 tribes. We also highlight the most pressing issues in antlion systematics and indicate taxa that need further taxonomic and phylogenetic attention. Finally, we present a comprehensive table placing all extant genera of antlions and owlflies in our new proposed classification, including details on the number of species, distribution and notes on the likely monophyly of each genus.     

Chromosomal segregational mechanisms in ant-lions (Myrmeleontidae,Neuroptera)

In a single male specimen of Myrmeleon mexicanum Banks the sex chromosomes, normally X and Y, were replaced by what appeared to be X¹X² and Y. These segregated as expected on that interpretation in only half of the spermatocytes — in the other half, one X and the Y segregated from the other X. This atypical segregation is explicable on the assumption that one of the supposed Xs is a supernumerary, not a sex chromosome, and the diploid complement of the male comprises six pairs of autosomes plus a supernumerary and the X and Y sex chromosomes. The orientation of the X chromosomes at first metaphase was variable: kinetochoric activity may be localized midway the length of the chromosome, as in gonial mitosis, or terminally. Comparative study of three congeneric species, seven of Brachynemurus, one of Psammoleon, and one of Vella showed normal segregation in all, and no evidence for secondary kinetochoric activity. In nine of the species studied one pair of autosomes was unconjoined at first metaphase in 0.3%–1.2% of primary spermatocytes. These autosomes segregated precociously with the sex chromosomes in the central unit of the spindle. In one exceptional male of Brachynemurus hubbardi Currie all first meiotic metaphases showed this behavior, and a compound X¹X²/Y¹Y² system was thus simulated. Bivalent formation replaced distance segregation of sex chromosomes in 0.4%–3.2% of the spermatocytes in seven of the thirteen species studied. These sex-bivalents frequently displayed partial or complete failure in congression.     

Antlions and owlflies (Neuroptera: Myrmeleontidae,Ascalaphidae) of Kyrgyzstan

The myrmeoleontoid Neuroptera fauna of Kyrgyzstan comprises 34 species-group taxa, among which 23 are recorded from the republic for the first time. Epacanthaclisis alaica Krivokhatsky, 1998 is known only from the holotype collected in the Alai Mt. Range; Kirghizoleon cubitalis Krivokhatsky et Zakharenko, 1994 is known from Kyrgyzstan and from the Hissar Mt. country in Tajikistan; and Mesonemurus vartianorum Hölzel, 1972 is distributed from the Tien Shan to Afghanistan. 26 species are common in Kyrgyzstan and are fairly evenly distributed over its territory. New synonymies are established: Macronemurus persicus (Navás, 1915) = Barreja persica Navás, 1915, = Barreja amoena Hölzel, 1972, syn. n.; Myrmecaelurus acerbus (Walker) = Myrmeleon acerbus Walker, 1853; = Myrmecaelurus varians Navás, 1913, syn. n.; = Myrmecaelurus aequans Navás, 1913, syn. n.; = Myrmecaelurus nematicus Navás, 1932, syn. n. The polymorphous structure of the widely variable Macronemurus persicus is shown, and three its color morphs are distinguished: Macronemurus persicus var. persica (Navás, 1915), var. graciosa var. n., and var. amoena (Hölzel, 1972). Data on the antlion and owlfly fauna of some other Palaearctic countries are supplemented.     

The First Mitochondrial Genomes of Antlion (Neuroptera: Myrmeleontidae) and Split-footed Lacewing (Neuroptera: Nymphidae), with Phylogenetic Implications of Myrmeleontiformia

In the holometabolous insect order Neuroptera (lacewings), the cosmopolitan Myrmeleontidae (antlions) are the most species-rich family, while the closely related Nymphidae (split-footed lacewings) are a small endemic family from the Australian-Malesian region. Both families belong to the suborder Myrmeleontiformia, within which controversial hypotheses on the interfamilial phylogenetic relationships exist. Herein, we describe the complete mitochondrial (mt) genomes of an antlion (Myrmeleon immanis Walker, 1853) and a split-footed lacewing (Nymphes myrmeleonoides Leach, 1814), representing the first mt genomes for both families. These mt genomes are relatively small (respectively composed of 15,799 and 15,713 bp) compared to other lacewing mt genomes, and comprise 37 genes (13 protein coding genes, 22 tRNA genes and two rRNA genes). The arrangement of these two mt genomes is the same as in most derived Neuroptera mt genomes previously sequenced, specifically with a translocation of trnC. The start codons of all PCGs are started by ATN, with an exception of cox1, which is ACG in the M. immanis mt genome and TCG in N. myrmeleonoides. All tRNA genes have a typical clover-leaf structure of mitochondrial tRNA, with the exception of trnS1(AGN). The secondary structures of rrnL and rrnS are similar with those proposed insects and the domain I contains nine helices rather than eight helices, which is common within Neuroptera. A phylogenetic analysis based on the mt genomic data for all Neuropterida sequenced thus far, supports the monophyly of Myrmeleontiformia and the sister relationship between Ascalaphidae and Myrmeleontidae.     

穴蚁蛉的研究

通过多年的观察研究,详细报导粤北穴蚁蛉的生态类型、生物学特性、个体发育与饲食频率的关系;介绍穴蚁蛉幼虫——蚁狮在治疗泌尿系统结石疾病中的重大药用价值和开发、保护蚁狮的方法和途径．     

On Variability of Two Arabian Myrmeleontoid Lacewings (Neuroptera: Myrmeleontidae,Ascalaphidae)

Entomological Review - Body-size dimorphism in the antlion Myrmeleon hyalinus hyalinus Olivier, 1811 is described; it is manifested in the existence of two size forms resulting from different...     

The mitochondrial genome of Gatzara jezoensis (Neuroptera: Myrmeleontidae) and phylogenetic analysis of Neuroptera

Phylogenetic relationship within Neuroptera is controversial, particularly for the various hypotheses based on both morphological and molecular evidence. In the present study, we determined the complete mitochondrial genome (mitogenome) of Gatzara jezoensis, which is the second representative of the tribe Dendroleontini. The G. jezoensis mitogenome contained the conserved set of 37 mitochondrial genes and a putative control region, with a conserved gene arrangement which was similar to that of most sequenced neuropteran mitogenomes. All transfer RNAs exhibited the canonical cloverleaf secondary structure, except for trnS^(AGN). The control region contained two conserved elements (ploy-T stretch and ATGGTTCAAYAAAATAAYYCYCTC motif) and abundant microsatellite-like elements. The phylogenetic analysis of sequenced neuropteran mitogenomes using the concatenated protein-coding genes (PCGs) and ribosomal genes recovered the monophyly of Myrmeleontidae, which revealed this dataset could generate the more robust phylogeny of Neuroptera than that of 13 PCGs dataset.     

锈翅蚁蛉(脉翅目:蚁蛉科)的发育生物学研究

锈翅蚁蛉为全变态类昆虫,在贵州省一年发生1代,11月下旬开始越冬,各龄幼虫均可越冬,次年3月苏醒.在室内饲养条件下,卵期13 d±0.56 d,幼虫期63.58 d±1.81d,蛹期26.35 d±1.14 d,成虫期20 d± 1.06 d.结合野外调查和室内饲养,详细描述了锈翅蚁蛉各虫态的形态特征,幼虫的筑穴、捕食、蜕皮、化蛹、羽化以及成虫的捕食、交配等行为习性.     

Thermal dependence of trap building in predatory antlion larvae (Neuroptera: Myrmeleontidae)

Trap-building predators remain under strong selection from thermal microenvironments. To address how soil temperature and body size affect trap building, we conducted a laboratory experiment using larvae of the antlion Myrmeleon bore at six ecologically relevant temperatures. Larger larvae built larger traps, and warmer soil led to more and larger traps. Body mass did not alter the dependence of trap building on temperature. Our results suggest that the physiological capacity of antlion larvae, which is affected by larval size and body temperature, is the major determinant of trap building. This effect should be considered when assessing interactions between antlions and prey.     

Learning in a sedentary insect predator: Antlions (Neuroptera: Myrmeleontidae) anticipate a long wait

Pit-building antlions, the larvae of a winged adult insect, capture food by digging funnel-shaped pits in sand and then lying in wait, buried at the vertex, for prey to fall inside. The sedentary nature of this sit-and-wait predatory behaviour and, especially, antlions’ innate ability to detect prey arrival, do not fit the typical profile of insects that possess learning capabilities. However, we show, for the first time, that learning can play an important role in this unique form of predation. In three separate experiments, individual antlions received, once per training day, either a vibrational cue presented immediately before the arrival of food or that same cue presented independently of food arrival. Signalling of food not only produced a learned anticipatory behavioural response (Experiment 1), but also conferred a fitness advantage: Associative learning enabled antlions to dig better pits (Experiments 2 and 3), extract food more efficiently (Experiments 2 and 3), and, in turn, moult sooner (Experiment 3) than antlions not receiving the associative learning treatment.     

Systematic revision,molecular phylogeny and biogeography of the antlion tribe Acanthoplectrini (Neuroptera: Myrmeleontidae: Dendroleontinae), with emphasis on the Oriental lineage

The tribe Acanthoplectrini (Myrmeleontidae: Dendroleontinae) includes a group of antlion genera widely distributed across the Australasian and Oriental regions. The intergeneric and interspecific relationships between or within the Australian and Oriental lineages of this tribe as well as their historical biogeography remain largely unexplored. Here, we present a molecular phylogenetic and biogeographic analyses of Acanthoplectrini to infer the diversification history of this tribe, with emphasis on the Oriental lineage. Both the Oriental and Australian lineages are monophyletic and recovered as sister groups. Ancestral area reconstruction suggests that the ancestor of Acanthoplectrini might have been once widely distributed from Indochina to Australia and then split into the Oriental and Australian lineages during the early-Miocene. Our analyses recovered northeastern Indochina and south China as the ancestral range of the Oriental Acanthoplectrini. During the mid-Miocene to the mid-Pliocene, orographic events such as the rising of mountain ranges (including the Himalayas) and the formation of major islands in southeastern Asia triggered several dispersal and vicariance events in the Oriental Acanthoplectrini, driving their speciation. We revise the classification of the Oriental Acanthoplectrini, establishing the new genus Paralayahima gen. n. , which is recovered sister to Layahima Navás. Moreover, we describe four new species of Layahima, Layahima aspoeckorum sp. n. , Layahima monba sp. n. , Layahima lhoba sp. n. and Layahima xinliae sp. n. , and we reinstate two previously synonymized species, Layahima melanocoris (Yang) stat. rev. and comb. n. and Layahima nebulosa Navás stat. rev.     

Comparative study of sensilla and other tegumentary structures of Myrmeleontidae larvae (Insecta,Neuroptera)

Antlion larvae have a complex tegumentary sensorial equipment. The sensilla and other kinds of larval tegumentary structures have been studied in 29 species of 18 genera within family Myrmeleontidae, all of them with certain degree of psammophilous lifestyle. The adaptations for such lifestyle are probably related to the evolutionary success of this lineage within Neuroptera. We identified eight types of sensory structures, six types of sensilla (excluding typical long bristles) and two other specialized tegumentary structures. Both sensilla and other types of structures that have been observed using scanning electron microscopy show similar patterns in terms of occurrence and density in all the studied species (with few exceptions). The sensilla identified are: coeloconica, placoidea, basiconica, trichodea type I, trichodea type II, and campaniformia. All these sensilla have mechano- or chemosensorial functions. Some regions of the larval body have been studied using SEM for the first time, such as the surface of the food canal, which bears sensilla coeloconica, and the abdominal segment X, that bears three types of sensilla: coeloconica, basiconica, and campaniformia. Sensilla placodea are newly reported on antlion larvae, being present on the mandibular base, pronotum, mentum, and cardum. Also, new locations of sensilla coeloconica (e.g., on rastra) and sensilla campaniformia (e.g., on odontoid processes) are noted. A novel porous texture with chemoreceptor function has been identified in the base of mandibles. A mechanism of dentate-notched surfaces that anchor maxillae and mandible, reinforcing the food canal, is detailed. All these sensorial structures, in addition to ocular tubercles for light caption and their great muscular system, confer to these larvae an extraordinary predation capacity to success hunting and living in such harsh environments.     

Utilisation of prey by antlion larvae (Neuroptera: Myrmeleontidae) in terms of energy and nutrients

Prey utilisation at low prey densities was determined for third instar Cueta sp., Furgella intermedia (Markl) and Palpares annulatus (Stitz) larvae in terms of wet weight, dry weight, energy and nutrients. Prey utilisation was similar to other insects on a wet weight (42-47%), dry weight (46-49%), energetic (40-58%) and nutritive basis (62-79%). Lipids (33-36%) provided energetically the highest contribution of the nutrients ingested. The quantities of water, proteins, nucleic acids, lipids and carbohydrates extracted by the antlion larvae were in proportion to their availability in their prey, the Hodotermes mossambicus larvae. The quantities of nutrients extracted by the antlion larvae at low prey densities were not significantly influenced by the differences in mandible size, antlion body weight or the trapping method (building a pit or not) of the antlion species. It is proposed that a low metabolic rate and the accumulation of fat reserves, and not the extent of prey utilisation, enable P. annulatus larvae to tolerate a 123-d starvation period in which 22.3% of their body weight is lost.     

The ant-lions of southern Africa: genus Pamexis Hagen (Neuroptera: Myrmeleontidae: Palparinae: Palparini)

Abstract. Pamexis Hagen, 1866, is revised. Myrmeleon luteum Thunberg is designated as type species. A key is provided for the five species comprising the genus. Pamexis luteus (Thunberg, 1784), P.bifasciatus (Olivier, 1811) and P.contaminatus (Hagen, 1887) are redescribed: P.karoo and P.namaqua are new species. All are endemic to the Cape Province of South Africa.     

Culture-Independent Characterization of the Microbiota of the Ant Lion Myrmeleon mobilis (Neuroptera: Myrmeleontidae)

Ant lions are insect larvae that feed on the liquefied internal components of insect prey. Prey capture is assisted by the injection of toxins that are reportedly derived from both the insect and bacterial symbionts. These larvae display interesting gut physiology where the midgut is not connected to the hindgut, preventing elimination of solid waste until adulthood. The presence of a discontinuous gut and the potential involvement of bacteria in prey paralyzation suggest an interesting microbial role in ant lion biology; however, the ant lion microbiota has not been described in detail. We therefore performed culture-independent 16S rRNA gene sequence analysis of the bacteria associated with tissues of an ant lion, Myrmeleon mobilis. All 222 sequences were identified as Proteobacteria and could be subdivided into two main groups, the α-Proteobacteria with similarity to Wolbachia spp. (75 clones) and the γ-Proteobacteria with similarity to the family Enterobacteriaceae (144 clones). The Enterobacteriaceae-like 16S rRNA gene sequences were most commonly isolated from gut tissue, and Wolbachia-like sequences were predominant in the head and body tissue. Fluorescence in situ hybridization analyses supported the localization of enterics to gut tissue and Wolbachia to nongut tissue. The diversity of sequences isolated from freshly caught, laboratory-fed, and laboratory-starved ant lions were qualitatively similar, although the libraries from each treatment were significantly different (P = 0.05). These results represent the first culture-independent analysis of the microbiota associated with a discontinuous insect gut and suggest that the ant lion microbial community is relatively simple, which may be a reflection of the diet and gut physiology of these insects.