Inclusion of rare taxa from Blattidae and Anaplectidae improves phylogenetic resolution in the cockroach superfamily Blattoidea

Cockroaches are an ecologically and economically important insect group, but some fundamental aspects of their evolutionary history remain unresolved. In particular, there are outstanding questions about some of the deeper relationships among cockroach families. As a group transferred from Blaberoidea Saussure to Blattoidea Latreille, the evolutionary history of the family Anaplectidae Walker requires re-evaluation. In our study, we infer the phylogeny of Blattoidea based on the mitochondrial genomes of 28 outgroup taxa and 67 ingroup taxa, including 25 newly sequenced blattoid species mainly from the families Anaplectidae and Blattidae Latreille. Our results indicate that Blattoidea is the sister group of the remaining Blattodea Brunner von Wattenwyl and that Blattoidea can be divided into three main clades: Blattidae + Tryonicidae McKittrick & Mackerras, Lamproblattidae McKittrick + Anaplectidae and Termitoidae Latreille + Cryptocercidae Handlirsch. Our analyses provide robust support for previously uncertain hypotheses. The sister group of Termitoidae + Cryptocercidae (Xylophagodea Engel) is inferred to constitute the rest of Blattoidea, for the first time. Within Blattidae, Hebardina Bey-Bienko is placed as the sister lineage to the rest of Blattidae. The subfamily Archiblattinae is polyphyletic, Blattinae is paraphyletic and Polyzosteriinae is monophyletic (Macrocercinae Roth not included); the genus Periplaneta Burmrister is polyphyletic. Based on the results of our phylogenetic analyses, we have revised these taxa. A new subfamily, Hebardininae subfam.nov. , is proposed in Blattidae. Archiblattinae and Shelfordella Adelung are synonymized with Blattinae and Periplaneta, respectively: Archiblattinae Kirby syn.nov. and Shelfordella Adelung syn.nov. Our inferred divergence times indicate that Blattoidea emerged in the Late Triassic, with six families in Blattoidea diverging in the Middle and Late Jurassic. We suggest that the divergences among lineages of Asian Blattidae and Anaplectidae were driven by the uplift of the Himalayas and deglaciation during the Quaternary, leading to the present-day distributions of these taxa.     

Complete mitochondrial genome of Periplaneta brunnea (Blattodea: Blattidae) and phylogenetic analyses within Blattodea

The complete mitochondrial genome (mitogenome) of Periplaneta brunnea was sequenced in this study and used to reconstruct the phylogenetic relationship of Blattodea. The circular mitogenome was 15,604?bp long and exhibited typical gene organization and order, consistent with other sequenced Periplaneta mitogenomes. The initiation codon of the P. brunnea COX1 gene was unusual in that no typical ATN or TTG start codon was found. The two longest intergenic spacer sequences found in the P. brunnea mitogenome were 21 and 17?bp long. Twenty-one base spacer had a 4?bp motif (TATT) between tRNA-Glu and tRNA-Met that conservatively displayed in 9 sequenced blattarian mitogenomes. The second spacer was between tRNA-Ser (UCN) and NAD1 containing a 7?bp motif (WACTTAA) that was highly conserved in 14 blattarian mitogenomes. The control region showed a relatively fixed motif present in 6 Blattidae mitogenomes, with a big stem-loop structure. Phylogenetic analyses were conducted using site-homogeneous models based on 13 protein-coding genes (PCGs) and two RNA genes. The trees derived from Bayesian inference and maximum likelihood analyses and recovered a relatively stable relationship among major lineages except for the position of Polyphagidae and inter-family relationships of Blaberidae. Analyses supported the monophyly of Blattidae, Blaberidae, Blattellidae, Polyphagidae, Dictyoptera, and the paraphyly of Blattaria. We also found Mantodea was the sister clade to (Blattaria?+?Isoptera), being the basal position of Dictyoptera in all topologies. Meanwhile, our results also consistently supported that Isoptera should be clustered with Blattaria of Blattodea.     

Phylogeny of cockroaches (Insecta,Dictyoptera, Blattodea), with placement of aberrant taxa and exploration of out‐group sampling

We addressed the phylogeny of cockroaches using DNA sequence data from a broad taxon sample of Dictyoptera and other non‐endopterygotan insect orders. We paid special attention to several taxa in which relationships are controversial, or where no molecular evidence has been used previously: Nocticolidae, a family of small, often cave‐dwelling cockroaches, has been suggested to be the sister group of the predaceous Mantodea or of the cockroach family Polyphagidae; Lamproblatta, traditionally placed in Blattidae, has recently been given family status and placed as sister to Polyphagidae; and Saltoblattella montistabularis Bohn, Picker, Klass & Colville, a jumping cockroach, which has not yet been included in any phylogenetic studies. We used mitochondrial (COI + COII and 16S) and nuclear (18S and 28S) genes, and analysed the data using Bayesian inference (BI) and maximum likelihood (ML). Nocticolidae was recovered as sister to Polyphagidae. Lamproblatta was recovered as sister to Blattidae, consistent with the traditional placement (not based on phylogenetic analysis). However, because of the limited support for this relationship and conflict with earlier morphology‐based phylogenetic hypotheses, we retain Lamproblattidae. S. montistabularis was consistently placed as sister to Ectobius sylvestris Poda (Blaberoidea: Ectobinae), indicating that the saltatorial hindlegs of this genus are a relatively recent adaptation. Isoptera was placed within Blattodea as sister to Cryptocercidae. Nocticolidae + Polyphagidae was sister to Isoptera + Cryptocercidae, and Blaberoidea was sister to the remaining Blattodea.     

Genome size evaluations in cockroaches: New entries

In this paper, we report genome size (GS) values for nine cockroaches (order Blattodea, families Blattidae, Blaberidae and Ectobiidae, ex Blattelidae), three of which are original additions to the ten already present in the GS database: the death’s head roach (Blaberus craniifer), the Surinam cockroach (Pycnoscelus surinamensis) and the Madeira cockroach (Leucophaea maderae). Regarding the American cockroach (Periplaneta americana), the GS database contains two contrasting values (2.72 vs 3.41 pg); likely, the 2.72 pg value is the correct one as it is strikingly similar to our sperm DNA content evaluation (2.80 ± 0.11 pg). Also, we suggest halving the published GS of the Argentine cockroach Blaptica dubia and the spotted cockroach (the gray cockroach) Nauphoeta cinerea discussing i) the occurrence of a correlation between increasing 2n chromosome number and GS within the order Blattodea; and ii) the possible occurrence of a polyploidization phenomenon doubling a basic GS of 0.58 pg of some termite families (superfamily Blattoidea, epifamily Termitoidae).Key words: genome size, C-DNA content, cockroaches, Blattodea     

Structure and function of the thecogen cell in contact chemosensitive sensilla of Periplaneta americana L. (Blattodea: Blattidae)

The functional morphology of the thecogen cell of the contact chemosensitive sensilla of the ventral sensory field on the maxillary palps of Periplaneta americana (Blattodea : Blattidae) was studied. There were electron-dense granules, which were examined using light and electron microscopy. Ultrastructural findings and acid phosphatase cytochemistry showed that these granules are lysosomes. The plasma membrane of the thecogen cell bordering the inner sensillum lymph also showed numerous coated pits. Intense fluid-phase endocytosis from the inner sensillum lymph into the thecogen cell was observed using Lucifer yellow as a fluorescent dye for infiltration. The endocytosed material is transported proximally and seems to be digested via the endosome-lysosome pathway. Lysosomes and endocytosis may serve the following functions: (1) the cleaning of the sensillum lymph from impurities entering via the tip porus; (2) the catabolic turnover during late embryonic development and before molting; (3) the continuous removal of stimulus molecules from the inner sensillum lymph after stimulation.     

New case of true mimicry in cockroaches (Blattodea)

True mimicry is an extremely rare phenomenon in cockroaches, with beetles as their favorite models. So far, only very few Pseudophyllodromiinae could be identified that conform to all requirements for Batesian mimicry and similarly exist only isolated reports on Müllerian mimicry. The vast majority, however, of the so‐called beetle‐mimicking cockroaches only shows a high degree of generalized convergence regarding their outer appearance. Specific models or counterparts, respectively, are lacking. Here we report on a last instar nymph of an undescribed Blattinae (Blattodea: Blattidae) that accurately mimics a truly harmful, sympatric carabid beetle. Although no indications for inedibility of this cockroach became evident, thus making Batesian mimicry likely, Müllerian mimicry can not be excluded with certainty. At any rate, this represents both the first case of mimicry in Blattidae and the first case with a ground beetle (Carabidae) as model for a cockroach mimic.     

Behavioural responses of diverse insect groups to electric stimuli

Anecdotal evidence suggests that cockroaches respond to electrical appliances or outlets. Our objectives were to determine the effect of field‐inducing sources and field attributes on attraction of German cockroaches, Blattella germanica (L.) (Blattodea: Blattellidae), and to test those parameters found effective for attraction of B. germanica for attraction of other groups of insects. In two‐choice, large‐arena experiments, significantly more female, but not nymphal, B. germanica settled in or near electrified coils with static or fluctuating electromagnetic fields produced by low‐level direct current (DC) or alternating current (AC) sources than in control coils without current. Electromagnetic fields with the magnetic, but not the electric, component of the field nulled still attracted B. germanica, suggesting that the electric component of the field may contribute to the attraction or arrestment response of B. germanica. DC‐powered coils with static electromagnetic fields also attracted/arrested brown‐banded cockroaches, Supella longipalpa (Fabricius) (Blattodea: Blattellidae), common silverfish, Lepisma saccharina (L.), firebrats, Thermobia domestica (Packard) (both Thysanura: Lepismatidae), and European earwigs, Forficula auricularia (L.) (Dermaptera: Forficulidae), but they repelled American cockroaches, Periplaneta americana (L.) (Blattodea: Blattidae). If proven in field experiments, electrified coils as trap baits may offer non‐toxic alternatives to pesticides for selective insect control in urban environments.     

Nymphs of the Oriental cockroach (Blatta orientalis) as passive vectors of causal agents of avian tuberculosis and paratuberculosis

The potential transmission of the causal agent of paratuberculosis Mycobacterium avium ssp. paratuberculosis and avian tuberculosis Mycobacterium avium ssp. avium (Actinomycetales: Mycobacteriaceae) by nymphs of the Oriental cockroach Blatta orientalis L. (Blattodea: Blattidae) was investigated by oral infection with mycobacterial suspensions and examination of their droppings and bodies. Both the subspecies of M. avium were isolated from droppings at 3 days post-infection and M. a. avium was found in homogenized bodies at 10 days post-infection. The identity of M. a. avium and M. a. paratuberculosis isolates was demonstrated by Restriction Fragment Length Polymorphism (RFLP) analysis. The M. a. avium isolate used as the inoculum and the isolates from the bodies and droppings of the nymphs were shown to be virulent in chickens. The results show that orally infected nymphs of B. orientalis can harbour and shed viable and virulent mycobacteria. This hazard should be considered in the implementation of control measures against mycobacterial infections of animals and humans, which should include destruction of all developmental stages of cockroaches and prevention of their access to materials that can be contaminated by mycobacteria.     

Embryonic development of Eucorydia yasumatsui Asahina,with special reference to external morphology (Insecta: Blattodea,Corydiidae)

As the first step in the comparative embryological study of Blattodea, with the aim of reconstructing the groundplan and phylogeny of Dictyoptera and Polyneoptera, the embryonic development of a corydiid was examined and described in detail using Eucorydia yasumatsui . Ten to fifteen micropyles are localized on the ventral side of the egg, and aggregated symbiont bacterial “mycetomes” are found in the egg. The embryo is formed by the fusion of paired blastodermal regions, with higher cellular density on the ventral side of the egg. This type of embryo formation, regarded as one of the embryological autapomorphies of Polyneoptera, was first demonstrated for “Blattaria” in the present study. The embryo undergoes embryogenesis of the short germ band type, and elongates to its full length on the ventral side of the egg. The embryo undergoes katatrepsis and dorsal closure, and then finally, it acquires its definitive form, keeping its original position on the ventral side of the egg, with its anteroposterior axis never reversed throughout development. The information obtained was compared with that of previous studies on other insects. “Micropyles grouped on the ventral side of the egg” is thought to be a part of the groundplan of Dictyoptera, and “possession of bacteria in the form of mycetomes” to be an apomorphic groundplan of Blattodea. Corydiid embryos were revealed to perform blastokinesis of the “non‐reversion type (N)”, as reported in blaberoid cockroaches other than Corydiidae (“Ectobiidae,” Blaberidae, etc.) and in Mantodea; the embryos of blattoid cockroaches (Blattidae and Cryptocercidae) and Isoptera undergo blastokinesis of the “reversion type (R),” in which the anteroposterior axis of the embryo is reversed during blastokinesis. Dictyopteran blastokinesis types can be summarized as “Mantodea (N) + Blattodea [= Blaberoidea (N) + Blattoidea (R) + Isoptera (R)]”.     

Length polymorphism of integrated copies of R1 and R2 retrotransposons in the German cockroach (Blattella germanica) as a potential marker for population and phylogenetic studies

Using polymerase chain reaction technique with primers flanking target sites of retrotransposons R1 and R2, integrated copies of these transposable elements were amplified in various cockroach species (Blattodea). It was shown that each species has a unique pattern of “5′-truncated copies” with the definite set of amplified fragments of different lengths. Intraspecies polymorphism was revealed in analysis of German cockroach specimens obtained upon individual mating. This is the first report providing results of identifying, cloning, and sequencing extended fragments (5′-truncated copies) of Blattella germanica R1 and R2 retrotransposons. It may be assumed that patterns of 5′-truncated copies of R1 and R2 elements can be used as markers in population and phylogenetic studies. Moreover, cloned and sequenced fragments will be employed in our further studies for screening of the German cockroach genomic library in order to detect full-length copies in this class transposable elements.     

Diversity of neurohormonal release sites in insects: Neurohemal areas associated with peripheral neurosecretory cells in Periplaneta americana L. (Dictyoptera: Blattidae) and Locusta migratoria R. & F. (Orthoptera : Locustidae)

Neurohemal areas are located on the distal region of the transverse nerve and on the link nerve of the cockroach, Periplaneta americana (Dictyoptera : Blattidae) and the locust, Locusta migratoria (Orthoptera : Locustidae). They constitute the sites at which the peripheral neurosecretory cells on these nerves discharge their products. Histological and ultrastructural studies suggest that, at least in Periplaneta, these areas also serve to release neurosecretory products different from those found in the perisympathetic organs (POs). These products come from the ganglion cells, some of them via the transverse nerve, and others, via the somatic nerves. The existence of these neurohemal areas broadens the problem of the release zones and shows that the POs are not the only neurohemal structures associated with ventral ganglion cells. An attempt is made to explain the reason for the existence of these different release sites, as well as the role of the peripheral cells.     

An ultrastructural study of the response of Blatella germanica (Orthoptera: Blattidae) to the nematode Abbreviata caucasica (Spirurida: Physalopteridae)

An ultrastructural study of the response of Blatella germanica (Orthoptera: Blattidae) to the nematode Abbreviata caucasica (Spirurida: Physalopteridea). International Journal for Parasitology4: 133–138. This study investigates the response of the roach, Blatella germanica L. to the invading spirurid nematode, Abbreviata caucasica v. Linstow. Soon after the first stage nematodes entered the epithelial cells of the colon wall, the surrounding host cells broke down into syncytial giant cells. Large polychromatic epithelial cell nuclei occurred throughout the giant cells and the nematodes moved freely within the cytoplasmic matrix. These giant cells were in turn surrounded by blood cells responding to the disruption. The nematodes developed to the infective third stage juveniles within the giant cells and ingested the syncytial cytoplasm. After reaching the third stage, the parasites remained in a quiescent state within the vacuolated cell which was surrounded by a double tissue layer.Evidence indicated that successful development of the parasite was dependent on the disrupted epithelial cells forming a giant syncytial cell which protected and supplied nourishment to the parasite.     

Death of an order: a comprehensive molecular phylogenetic study confirms that termites are eusocial cockroaches

Termites are instantly recognizable mound-builders and house-eaters: their complex social lifestyles have made them incredibly successful throughout the tropics. Although known as 'white ants', they are not ants and their relationships with other insects remain unclear. Our molecular phylogenetic analyses, the most comprehensive yet attempted, show that termites are social cockroaches, no longer meriting being classified as a separate order (Isoptera) from the cockroaches (Blattodea). Instead, we propose that they should be treated as a family (Termitidae) of cockroaches. It is surprising to find that a group of wood-feeding cockroaches has evolved full sociality, as other ecologically dominant fully social insects (e.g. ants, social bees and social wasps) have evolved from solitary predatory wasps.     

A proteomic approach for studying insect phylogeny: CAPA peptides of ancient insect taxa (Dictyoptera, Blattoptera) as a test case

Background  

Neuropeptide ligands have to fit exactly into their respective receptors and thus the evolution of the coding regions of their genes is constrained and may be strongly conserved. As such, they may be suitable for the reconstruction of phylogenetic relationships within higher taxa. CAPA peptides of major lineages of cockroaches (Blaberidae, Blattellidae, Blattidae, Polyphagidae, Cryptocercidae) and of the termite Mastotermes darwiniensis were chosen to test the above hypothesis. The phylogenetic relationships within various groups of the taxon Dictyoptera (praying mantids, termites and cockroaches) are still highly disputed.     

Feeding behaviour of Belminus ferroae (Hemiptera: Reduviidae), a predaceous Triatominae colonizing rural houses in Norte de Santander,Colombia

Belminus ferroae (Hemiptera: Reduviidae) was collected from houses in the localities of San Alberto and Santa Catalina in the municipality of Toledo, Department of Norte de Santander, Colombia. Precipitin tests revealed that the main hosts of B. ferroae are insects belonging to the order Blattodea, whose haemolymph serves as food (89.43%). A low rate of haematophagy was indicated on rodents, dogs and humans (7.32%) and no natural infection with Trypanosoma cruzi was found by either microscopic examination or polymerase chain reaction. The finding of B. ferroae inside houses, feeding primarily on Blattodea with only a minor tendency to feed on vertebrate blood, is indicative of both the evolutionary path from predator to blood‐sucker taken by Triatominae and their tendency to adapt from silvatic to domestic habitats.     

Phylogenetic relationship among cockroach families inferred from mitochondrial12S rRNA gene sequence

A number of phylogenies exist for cockroaches that differ in the postulated relationships among families and genera. The relationship of the wood-feeding genus, Cryptocercus, to other cockroach families and to termites, has generated considerable debate. Grandcolas (1994), based on morphological analysis, synonymized the family Cryptocercidae with Polyphagidae and placed the genus Cryptocercus in the subfamily Polyphaginae. To determine if an independent set of characters supports the placement of Cryptocercus in Polyphaginae, a phylogenetic analysis of relationships among representative genera of the five cockroach families was undertaken. DNA sequence of a -430 base pair portion of the mitochondrial small ribosomal subunit gene from representatives of Blattidae, Blattellidae, Blaberidae and Cryptocercus, previously published by Kambhampati (1995) and Kambhampati et al. (1996), and the homologous sequence from representatives of Polyphagidae were used in the analysis. A total of twenty cockroach taxa and three termite genera were included in the study. Because a recent study showed that Cryptocercus punctulatus consists of a species complex, DNA sequence from four individuals collected in different parts of the U.S.A. was included in the study. The trees estimated from parsimony and neighbour-joining analyses indicated that Cryptocercus is a monophyletic clade which is most closely related to members of Blattidae. Polyphagidae is indicated as a sister group to the Blattidae + Cryptocercus complex, suggesting that Polyphagidae may belong to the superfamily Blattoidea rather than to Blaberoidea as proposed by McKittrick (1964). Blaberidae and Blattellidae were sister groups as previously proposed. Based on the present analysis, I propose that the genus Cryptocercus be retained in the family Cryptocercidae. Cockroaches     

Evolution and phylogenetic information content of the ribosomal DNA repeat unit in the Blattodea (Insecta)

The organization, structure, and nucleotide variability of the ribosomal repeat unit was compared among families, genera, and species of cockroaches (Insecta:Blattodea). Sequence comparisons and molecular phylogenetic analyses were used to describe rDNA repeat unit variation at differing taxonomic levels. A reverse similar 1200 bp fragment of the 28S rDNA sequence was assessed for its potential utility in reconstructing higher-level phylogenetic relationships in cockroaches. Parsimony and maximum likelihood analyses of these data strongly support the expected pattern of relationships among cockroach groups. The examined 5' end of the 28S rDNA is shown to be an informative marker for larger studies of cockroach phylogeny. Comparative analysis of the nucleotide sequences of the rDNA internal transcribed spacers (ITS1 and ITS2) among closely related species of Blattella and Periplaneta reveals that ITS sequences can vary widely in primary sequence, length, and folding pattern. Secondary structure estimates for the ITS region of Blattella species indicate that variation in this spacer region can also influence the folding pattern of the 5.8S subunit. These results support the idea that ITS sequences play an important role in the stability and function of the rRNA cluster.     

Pattern of bacteriocyte formation in Periplaneta americana (L.) (Blattaria: Blattidae)

In the embryos of Periplaneta americana (L.) (Blattaria: Blattidae), bacterial symbionts, together with vitellophages, form a mycetomic structure inside the deutoplasm; this regresses between the 15th and 16th day after deposition of the ootheca. In this article we describe the migration of bacteria across the wall of the midgut from the mycetome, and the topographic distribution of pre-bacteriocyte cells. We also report that the pre-bacteriocytes are present only on the lateral surface of the internal abdominal fat bodies. We discuss the possible embryological origin and evolution of these cells, and put forward the hypothesis that pre-bacteriocytes are derived from oenocytes activated to perform phagocytosis.