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The German cockroach, Blattella germanica , can be a vector of human enteric bacterial pathogens, including Salmonella enterica serovar Typhimurium (S. Typhimurium). Transmission of such pathogens by cockroaches has largely been considered a passive mechanical process, but recent studies have argued against this dogma by demonstrating bacterial proliferation within the cockroach gut and the necessity of specific bacterial genes for successful transmission in the feces, revealing unappreciated biological complexity in the vector-pathogen relationship between cockroaches and S. Typhimurium. However, the influence of naturally occurring variation among cockroach populations on pathogen infection and dissemination has not been investigated. Thus, this study aimed to examine whether distinct strains of B. germanica exhibit differences in their ability to become infected by and disseminate S. Typhimurium. We performed controlled infections of one long-term laboratory strain and three recently field-collected strains reared under identical conditions, then compared bacterial loads in the body and excreta of individual insects. Separately, we also compared rates of necrophagy, a behavior known to contribute to the horizontal spread of S. Typhimurium among cockroaches. Our data show significant differences in infection susceptibility, pathogen shedding in the excreta, and necrophagy between laboratory and field strains as well as between some field strains. These observations represent the first evidence that genomic variation among cockroach populations may influence their ability to become infected by and disseminate pathogens, providing further support for the hypothesis that German cockroaches are active biological vectors rather than passive mechanical vectors of S. Typhimuriu m. Additional studies are needed to identify the genomic drivers of vector competence for S. Typhimurium in B. germanica. • Differences in susceptibility to Salmonella among B. germanica strains were identified. • Differences in Salmonella excretion among B. germanica strains were identified. • Differences in necrophagy behavior among B. germanica strains were identified. [ABSTRACT FROM AUTHOR]

Present-day pterygote insects have two pairs of wings, one in the mesothorax (T2), the other in the metathorax (T3), and both have diverged in structure and function in different groups. Studies in endopterygote and paraneopteran species have shown that the gene Ultrabithorax (Ubx) specifies the identity and wing structure in T3, whereas the gene apterous (ap) significantly contributes to forming modified T2 wings. We wondered whether these Ubx and ap mechanisms operate in the lineage of polyneopterans. To explore this possibility, we used the cockroach Blattella germanica (Polyneoptera and Blattodea), in which the T2 wings are sclerotized (tegmina), whereas those of the T3 are membranous. We found that Ubx determines the structure of T3 and the membranous wing, while ap significantly contributes to form the sclerotized T2 tegmina. These results along with the studies carried out on the beetle Tribolium castaneum by Tomoyasu and collaborators suggest that ap plays an important role in the sclerotization and melanization of the T2 wings in neopteran groups that have sclerotized forewings. In turn, the sclerotizing properties of ap demonstrated in beetles and cockroaches suggest that the origin of this function goes back to the emergence of Neoptera, in the mid Devonian. [ABSTRACT FROM AUTHOR]

Omnivorous synanthropic cockroaches, such as the German cockroach (Blattella germanica), are reservoirs and vectors of enteric bacterial pathogens. A lifestyle conducive to frequent encounters with high loads of diverse bacteria may have led to the evolution of unique innate immune systems in these insects. The innate immune response of insects relies largely on generalized mechanisms to sense and eliminate foreign microbes. However, analyses of the genomes of common synanthropic cockroaches previously revealed a repertoire of pathogen associated molecular pattern (PAMP) receptors and antimicrobial peptides (AMPs) that is significantly expanded relative to most holometabolous insect models and vectors, supporting the intriguing possibility that cockroaches may encode enhanced recognition within their immune system and may possess an enhanced capacity to fine tune innate immune responses. Investigating how cockroaches respond to infection with enterobacteria provides the opportunity to expand our fundamental knowledge of the regulation of insect innate immunity in a context that is biologically and medically relevant. German cockroaches can harbor both Salmonella enterica serovar Typhimurium and Escherichia coli in their gut without experiencing pathogenesis. The former colonizes the gut and replicates while the latter persists only transiently. We hypothesized that differences in the innate immune response may contribute to or result from the difference in infection dynamics between the two enterobacteria. To test this hypothesis, we used qRT-PCR to analyze expression of five genes encoding representative AMPs (Attacins, Blattellicin, Defensins) in the gut of German cockroaches 1 and 24 h after ingestion of live or heat-killed enterobacteria. We found that robust AMP expression was induced in response to ingestion of a live wild-type strain of S. Typhimurium, but not in response to live E. coli, heat-killed S. Typhimurium, or a live mutant strain of S. Typhimurium lacking type III secretion systems. These results indicate that the cockroach immune system does not respond to stimulation with high levels of ingested bacterial PAMPs such as peptidoglycan. Rather, AMP expression in the gut appears to be induced by active bacterial colonization involving type III secretion. We speculate that this form of regulation may have evolved to prevent over activation of the immune system from frequent ingestion of innocuous, non-colonizing, or non-viable bacteria. While additional work is needed to delineate the molecular mechanisms underlying our observations, our findings provide significant novel insight into the immunological adaptation of cockroaches to life in septic environments as well as the factors that regulate bacterial pathogen transmission by these insects.

Copyright of Annali di Igiene, Medicina Preventiva e di Comunità is the property of Societa Editrice Universo s.r.l. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The knowledge of Blattodea from Oman is still incipient. One species of cockroaches are reported from Oman so far and this indicates the large blank in our knowledge in this order when compared to recorded species from other neighboring countries in the Arabian Peninsula. Blattodea have been collected at various localities in Sultanate of Oman with different sampling artifacts. The present communication records five species of cockroaches from Oman, namely Blattella biligata (Walker, 1868), Heterogamisca Bey-Bienko, 1950, Pycnoscelus surinamensis (Linnaeus, 1758), Tivia fusca Bohn, 2008 from northern Oman and Neostylopyga rhombifolia (Stoll, 1813) from southern Oman.

The German cockroach (Blattella germanica) is a cosmopolitan omnivorous species which can take nutrients from a wide variety of sources. Its condition of pest generated interest in the study of its biology, and while there are many works regarding its feeding behavior, few approaches have been made to the relevance of the chemosensory system during foraging. Objective: In this work we studied the role of chemical stimuli in the detection and preference of food sources in B. germanica using behavioral observations. Methods: Adult males were placed in a circular experimental arena where different diet types were presented individually. Parameters associated to the detection of odors (latency to the food source, number of visits to the source) were measured in an experimental time of 15 minutes. We also measured the total amount ingested determining the weight gain of each individual, as an indicator of taste evaluation of food. Findings: Insects showed a lower latency when the source emitted a larger amount of volatile compounds, so peanut butter was detected faster compared with the other diets studied. Regarding ingestion, insects spent significantly more time on the peanut butter, indicating the presence of phagostimulants such as sugars or lipids. When sugar solutions were used as food sources, the number of visits, the time spent on the source and the amount consumed was higher when increasing sugar concentration. Insects also showed preference for the solution of higher concentration, when two sugar solutions were presented simultaneously. Latency increased and the amount of sugar ingested decreased when insects´ mouthparts were chemically blocked with N-Ethylmaleimide, a general inhibitor of chemoreception. Novelty/Improvement: These results describe how cockroaches use odors to locate food sources and chemoreceptors in their mouthparts to identify diets of higher energetic value, from information regarding the concentration and quality of the food source. Understanding the feeding behavior of cockroaches allows the design of more attractive and palatable toxic gel baits enhancing their efficacy for cockroach control.

Abstract Background Do miRNAs contribute to specify the germ-band type and the body structure in the insect embryo? Our goal was to address that issue by studying the changes in miRNA expression along the ontogeny of the German cockroach Blattella germanica, which is a short germ-band and hemimetabolan species. Results We sequenced small RNA libraries representing 11 developmental stages of B. germanica ontogeny (with especial emphasis on embryogenesis) and the changes in miRNA expression were examined. Data were compared with equivalent data for two long germ-band holometabolan species Drosophila melanogaster and Drosophila virilis, and the short germ-band holometabolan species Tribolium castaneum. The identification of B. germanica embryo small RNA sequences unveiled miRNAs not detected in previous studies, such as those of the MIR-309 family and 54 novel miRNAs. Four main waves of miRNA expression were recognized (with most miRNA changes occurring during the embryonic stages): the first from day 0 to day 1 of embryogenesis, the second during mid-embryogenesis (days 0–6), the third (with an acute expression peak) on day 2 of embryonic development, and the fourth during post-embryonic development. The second wave defined the boundaries of maternal-to-zygotic transition, with maternal mRNAs being cleared, presumably by Mir-309 and associated scavenger miRNAs. Conclusion miRNAs follow well-defined patterns of expression over hemimetabolan ontogeny, patterns that are more diverse during embryonic development than during the nymphal stages. The results suggest that miRNAs play important roles in the developmental transitions between the embryonic stages of development (starting with maternal loading), during which they might influence the germ-band type and metamorphosis mode.

In adult females of the cockroach Blattella germanica, juvenile hormone (JH) promotes vitellogenin production. Depletion of Methoprene-tolerant (Met) mRNA levels with RNAi resulted in a clear reduction of vitellogenin expression in the fat body while basal oocyte growth was impaired. This demonstrates that Met is essential to transduce the vitellogenic signal of JH in this species. Interestingly, the expression of the transcription factor Kruppel homolog 1 (Kr-h1) was also reduced in Met-depleted specimens. This indicates that the JH signaling pathway promotes the transcription of Kr-h1 in adult fat body tissues, as occurs in the epidermis during nymphal development. Treatments with JH show that the expression of Met does not depend on JH, which suggests that Met is upstream the JH signaling pathway acting as JH receptor, as reported in other models and processes, especially in metamorphosis. JH treatments increased the transcription levels of vitellogenin and Kr-h1, which again suggests that Kr-h1 is a JH-dependent transcription factor in the fat body of adult females. The important roles of Met in nymphal development, as previously reported, and those reported herein in relation to reproduction, suggests that it can be an interesting target for the control of B. germanica in urban environments, using RNAi approaches.

Many current issues in evolutionary biology focus on social behaviour. These include the re-purposing of neuroendocrine systems and cell signalling during the asocial to social transition, the behavioural and evolutionary dynamics of interacting genomes, the resolution of intralocus conflict, nongenetic inheritance and buffering of environmental stress. Representative examples of parent and offspring physiology are discussed, with emphasis on social interaction. This proximate background is used to address current controversies in the study of social evolution. This review will suggest how insect families, which range from simple to highly eusocial, are amenable subjects for combining behavioural, physiological and molecular study to advance our understanding of the evolutionary process. [ABSTRACT FROM AUTHOR]

Abstract: Inheritance of 5'-truncated copies of R2 retrotransposon of German cockroach, Blattella germanica, was analyzed in a series of generations. It was shown that copies of certain length are linked and form different patterns associated with X chromosomes where R2 retrotransposons are normally localized within clusters of ribosomal genes and, unexpectedly with autosomes. There was no recombination between certain copies of different length, and new variants of 5'-truncated copies were not found. Taking into account the stable inheritance of particular patterns of various R2 5'-truncated copies, we suggest using them as convenient molecular markers in population genetics studies of German cockroach, Blattella germanica. It was also shown that only short degenerate DNA sequences of R2 retrotransposon were present outside the cluster of ribosomal genes; apparently, DNA sequences corresponding to native full-length copies and/or open reading frames of R2 retrotransposon are present only within the cluster. [ABSTRACT FROM AUTHOR]

Copyright of BBA - Gene Regulatory Mechanisms is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Lufenuron is a chitin synthesis inhibitor used for controlling several pest insects. The German cockroach, Blattella germanica, is a cosmopolitan insect of medical and economic importance. Resistance to insecticides has been worldwide reported in this species. The objective of this work was to evaluate the effect of lufenuron in two colonies of B. germanica, one susceptible to insecticides (CIPEIN) and another pyrethroid-resistant (JUBA). Experimental populations from each colony were exposed to filter papers treated with 50 mg of lufenuron/m². Controls were exposed to filter papers treated with solvent alone. After seven weeks, the average size of both lufenuron-treated populations was 1.33 ± 0.7 individuals, while the average size of control populations were 206.5 ± 39.5 (CIPEIN) and 136.5 ± 43.5 (JUBA) individuals. This drastic effect suggests that lufenuron could be used as an alternative for the control of pyrethroid-resistant German cockroaches. Future studies should explore the toxicity of lufenuron on other populations of B. germanica resistant to pyrethroids or other insecticides. [ABSTRACT FROM AUTHOR]

The role of juvenile hormone (JH) in insect embryos is far from understood, especially in short germ-band hemimetabolan species. To shed light on this issue, we depleted the mRNA levels of Krüppel homolog 1, Methoprene-tolerant and JH acid O-methyltransferase, key elements of JH signaling, in embryos of the short germ-band hemimetabolan species Blattella germanica. This precluded the formation of the germ-band anlage in a group of embryos. Hatchability was also reduced, which might have been caused by premature upregulation of laccase 2, a promoter of cuticle tanning. In other cases, development was interrupted in mid embryogenesis, involving defects related to dorsal closure and appendage formation. These phenotypes possibly result from the low levels of Broadcomplex (BR-C) produced under JH-depleted conditions. This contrasts with holometabolan species, in which JH does not promote BR-C expression, which remains low during embryo development. Possibly, the stimulatory role of JH on BR-C expression and the morphogenetic functions of BR-C in hemimetabolan embryos were lost in holometabolan species. If so, this might have been a key driver for the evolution of holometabolan metamorphosis. [ABSTRACT FROM AUTHOR]

The present study assessed the capacity of Blattella germanica and Periplaneta americana to disseminate and transmit infective phases of T. canis to rats, which were used as a model paratenic host. P. americana and B. germanica inoculated orally with T. canis larvated eggs shed eggs and larvae in their fecal matter during the first 6 days post-inoculation. Larvae were recovered from the brain, lungs, kidneys and liver of rats that had been inoculated with either infected cockroaches or their feces. ELISAs of serum detected an increase of antibodies anti- T. canis excretion-secretion antigens, whereas Western Blot (WB) showed 4 bands (120, 50, 35 and 28 kDa) that were similar to those found in positive control rats. Macroscopically, the liver and kidneys of infected rats had hemorrhagic areas with milk-spot-like lesions. The lungs showed diffuse grey protuberances. Histologically, hemorrhagic areas with leucocytic infiltrate were observed in the liver, lungs and kidneys. Some larvae were found within a granuloma that was surrounded by eosinophils and other leucocytic infiltrates. Larvae were found in the brain, but without inflammatory infiltrate. Both cockroach species that ingested larvated eggs of T. canis may shed viable larvae or eggs in their fecal matter. The induction of specific serum antibodies, presence of larvae in tissues and characteristic lesions associated with larval migration in the organs of rats that had ingested either whole adults or feces of B. germanica or P. americana demonstrate the capacity of these cockroaches to transmit toxocariosis to paratenic hosts. [ABSTRACT FROM AUTHOR]

Background: Do miRNAs contribute to specify the germ-band type and the body structure in the insect embryo? Our goal was to address that issue by studying the changes in miRNA expression along the ontogeny of the German cockroach Blattella germanica, which is a short germ-band and hemimetabolan species. Results: We sequenced small RNA libraries representing 11 developmental stages of B. germanica ontogeny (with especial emphasis on embryogenesis) and the changes in miRNA expression were examined. Data were compared with equivalent data for two long germ-band holometabolan species Drosophila melanogaster and Drosophila virilis, and the short germ-band holometabolan species Tribolium castaneum. The identification of B. germanica embryo small RNA sequences unveiled miRNAs not detected in previous studies, such as those of the MIR-309 family and 54 novel miRNAs. Four main waves of miRNA expression were recognized (with most miRNA changes occurring during the embryonic stages): the first from day 0 to day 1 of embryogenesis, the second during mid-embryogenesis (days 0-6), the third (with an acute expression peak) on day 2 of embryonic development, and the fourth during post-embryonic development. The second wave defined the boundaries of maternal-to-zygotic transition, with maternal mRNAs being cleared, presumably by Mir-309 and associated scavenger miRNAs. Conclusion: miRNAs follow well-defined patterns of expression over hemimetabolan ontogeny, patterns that are more diverse during embryonic development than during the nymphal stages. The results suggest that miRNAs play important roles in the developmental transitions between the embryonic stages of development (starting with maternal loading), during which they might influence the germ-band type and metamorphosis mode. [ABSTRACT FROM AUTHOR]

In terrestrial ecosystems, cockroaches are important decomposers that consume dead and decaying plants and animals. However, little attention has been paid to their roles in mutualistic interactions with living plants. In an anecdotal observation, the forest cockroach, Blattella nipponica, was identified as a fruit consumer of Monotropastrum humile, a mycoheterotrophic herb. The species may be a potential seed dispersal agent, but seed dispersal by cockroaches has never been shown in plants. In the present study, we investigated the seed dispersal mechanism of M. humile in temperate forests of Japan to determine whether fruit-feeding cockroaches were classified as legitimate seed dispersers or mere consumers. The dull-white, fleshy fruits attracted a variety of arthropods, but not birds and mammals. Of those arthropods, only the forest cockroaches consistently visited and consumed the less juicy pulp embedded with numerous minute seeds and their excreted frass contained intact and viable seeds. These results indicate that B. nipponica can act as the legitimate seed disperser of M. humile. Given that the cockroach order Blattodea s.s. are a modestly species-rich, cosmopolitan taxon (c. 4600 described species), seed dispersal by cockroaches may be a pervasive, but as yet undocumented, dispersal mechanism. [ABSTRACT FROM AUTHOR]

Wings were a fundamental morphological innovation for the adaptive radiation of insects, the most diversified group among all animals. Pterygote insects have two pairs of wings, the mesothoracic (T2) forewings and the metathoracic (T3) hindwings, whereas the prothorax (T1) is wingless. Using RNA interference approaches, we have found that the gene Sex combs reduced (Scr) determines the wingless identity of T1 in the cockroach Blattella germanica. Interference of Scr triggers the formation of ectopic wing structures in T1, which are formed from the expansion of the latero-posterior region of the pronotum, along with a contribution of the epimeron, a pleurite of T1. These data support the theory of a dual origin for insect wings, from pronotal (tergal origin theory) and pleural (pleural origin theory) structures and genes.

In contrast with Drosophila melanogaster , practically nothing is known about the involvement of the TGF-β signaling pathway in the metamorphosis of hemimetabolan insects. To partially fill this gap, we have studied the role of Smad factors in the metamorphosis of the German cockroach, Blattella germanica . In D. melanogaster , Mad is the canonical R-Smad of the BMP branch of the TGF-β signaling pathway, Smox is the canonical R-Smad of the TGF-β/Activin branch and Medea participates in both branches. In insects, metamorphosis is regulated by the MEKRE93 pathway, which starts with juvenile hormone (JH), whose signal is transduced by Methoprene-tolerant (Met), which stimulates the expression of Krüppel homolog 1 (Kr-h1) that acts to repress E93, the metamorphosis trigger. In B. germanica , metamorphosis is determined at the beginning of the sixth (final) nymphal instar (N6), when JH production ceases, the expression of Kr-h1 declines, and the transcription of E93 begins to increase. The RNAi of Mad, Smox and Medea in N6 of B. germanica reveals that the BMP branch of the TGF-β signaling pathway regulates adult ecdysis and wing extension, mainly through regulating the expression of bursicon, whereas the TGF-β/Activin branch contributes to increasing E93 and decreasing Kr-h1 at the beginning of N6, crucial for triggering adult morphogenesis, as well as to regulating the imaginal molt timing. [ABSTRACT FROM AUTHOR]

SUMOylation, the covalent binding of Small Ubiquitin-like Modifier (SUMO) to target proteins, is a posttranslational modification that regulates critical cellular processes in eukaryotes. In insects, SUMOylation has been studied in holometabolous species, particularly in the dipteran Drosophilamelanogaster, which contains a single SUMO gene (smt3). This has led to the assumption that insects contain a single SUMO gene. However, the analysis of insect genomes shows that basal insects contain two SUMO genes, orthologous to vertebrate SUMO1 and SUMO2/3. Our phylogenetical analysis reveals that the SUMO gene has been duplicated giving rise to SUMO1 and SUMO2/3 families early inMetazoan evolution, and that later in insect evolution the SUMO1 gene has been lost after the Hymenoptera divergence. To explore the consequences of this loss, we have examined the characteristics and different biological functions of the two SUMO genes (SUMO1 and SUMO3) in the hemimetabolous cockroach Blattella germanica and compared them with those of Drosophila Smt3. Here, we show that the metamorphic role of the SUMO genes is evolutionary conserved in insects, although there has been a regulatory switch from SUMO1 in basal insects to SUMO3 in more derived ones. We also show that, unlike vertebrates, insect SUMO3 proteins cannot form polySUMO chains due to the loss of critical lysine residues within the N-terminal part of the protein. Furthermore, the formation of polySUMO chains by expression of ectopic human SUMO3 has a deleterious effect in Drosophila. These findings contribute to the understanding of the functional consequences of the evolution of SUMO genes. [ABSTRACT FROM AUTHOR]

The tergal gland is a structure exclusive of adult male cockroaches that produces substances attractive to the female and facilitates mating. It is formed de novo in tergites 7 and 8 during the transition from the last nymphal instar to the adult. Thus, the tergal gland can afford a suitable case study to investigate the molecular basis of a morphogenetic process occurring during metamorphosis. Using Blattella germanica as model, we constructed transcriptomes from male tergites 7–8 in non-metamorphosing specimens, and from the same tergites in metamorphosing specimens. We performed a de novo assembly all available transcriptomes to construct a reference transcriptome and we identified transcripts by homology. Finally we mapped all reads into the reference transcriptome in order to perform analysis of differentially expressed genes and a GO-enrichment test. A total of 5622 contigs appeared to be overrepresented in the transcriptome of metamorphosing specimens with respect to those specimens that did not metamorphose. Among these genes, there were six GO-terms with a p-value lower than 0.05 and among them GO: 0003676 (“nucleic acid binding”) was especially interesting since it included transcription factors (TFs). Examination of TF-Pfam-motifs revealed that the transcriptome of metamorphosing specimens contains the highest diversity of these motifs, with 29 different types (seven of them exclusively expressed in this stage) compared with that of non-metamorphosing specimens, which contained 24 motif types. Transcriptome comparisons suggest that TFs are important drivers of the process of tergal gland formation during metamorphosis. [ABSTRACT FROM AUTHOR]

The Asian cockroach, Blattella asahinai Mizukubo, first introduced to Florida in 1986, has been spreading throughout the southeastern United States. Populations can reach extremely high densities and cause damage to crops as well as become a nuisance in residential settings. Because the German cockroach, Blattella germanica L., is its closest extant relative, we characterized the B. asahinai male response to blattellaquinone, the sex pheromone of the German cockroach, in an effort to develop monitoring tools for B. asahinai. Electroantennogram (EAG) analysis was conducted on B. asahinai and B. germanica males and females, and revealed that the antennae of males of both species responded significantly more to blattellaquinone than females, and in both males and females absolute EAG responses of B. asahinai were greater than in B. germanica males and females, respectively. However, normalized male EAG response curves and ED50 values (effective dose to elicit 50% of maximal response) did not differ significantly between the two species. Results of field trapping experiments demonstrated that male B. asahinai were more attracted to blattellaquinone than any other life stage, and 10 lg of blattellaquinone attracted the most males. These results suggest that blattellaquinone or a similar compound might be a component of the sex pheromone of B. asahinai females. [ABSTRACT FROM AUTHOR]

In hemimetabolan insects, the transcription factor Broad complex (Br–C) promotes wing growth and development during the nymphal period. We wondered whether Br–C could trigger the initiation of wing development, using the cockroach Blattella germanica as a model. We show that first instar nymphs have their unique identity of these three thoracic segments specified. During embryogenesis, the expression of Br–C and some wing-related genes show two matching waves. The first takes place before the formation of the germ band, which might be involved in the establishment of various developmental fields including a potential "wing field", and the second wave around organogenesis, possibly involved in the initiation of wing development. However, the expression of Br–C in early embryogenesis concentrates in the developing central nervous system, thus not co-localizing with the expression of the typical wing-related gene vestigial , which is expressed at the edge of the thoracic and abdominal segments. This suggests that Br–C is not specifically involved in the establishment of a potential "wing field" in early embryogenesis. Moreover, maternal RNAi for Br–C depletes the first wave of Br–C expression but does not affect the early expression of wing-related genes. As maternal Br–C RNAi did not deplete the second expression wave of Br–C , we could not evaluate if Br–C is involved in the initiation of wing development. Alternatively, using nymphal RNAi of Br–C and Sex combs reduced (Scr), we show that Br–C contributes to the formation of ectopic wing structures that develop in the prothorax when Scr is depleted. The gene most clearly influenced by Br–C RNAi is nubbin (nub), which, in nymphs is crucial for wing growth. Together, these results suggest that Br–C does not specifically contribute to the establishment of the "wing field", but it does seem important later, in the initiation of wing development, enhancing the expression of wing-related genes, especially nub. This supports the hypothesis previously proposed by the authors, whereby Br–C might have facilitated the evolution of holometaboly. However, there is no doubt that other factors have also contributed to this evolution. [Display omitted] • Blattella germanica embryos express Br–C in respective waves at early and mid stage. • Expression of wing-related genes follows a pattern similar to that of Br–C. • Br–C may be involved in the initiation of wing development at mid embryogenesis. • In nymphs, Br–C contributes to the growth of ectopic wing structures in the prothorax. • In nymphs, Br–C enhances the expression of nubbin , promoting meso- and metathoracic wing growth. [ABSTRACT FROM AUTHOR]

Toxicity, repellency, and performance of three insecticides, β-cyfluthrin EC, fipronil granules, and an essential oil EC formulation, were evaluated against the Asian cockroach, Blattella asahinai Mizukubo, in field and laboratory experiments. The β-cyfluthrin EC and fipronil granules were significantly more toxic than the essential oil EC formulation under continuous exposure conditions, with LT50 values of 0.014,0.45, and 11.45 d, respectively. The β-cyfluthrin EC and fipronil granules were also significantly more toxic than the essential oil EC formulation in an Ebeling choice box test with LT50 values of 0.64, 1.98, and 59.64 d, respectively. Field applications of insecticides at label rates to Asian cockroach populations in Dothan, AL, showed that β-cyfluthrin EC and fipronil granules reduced populations by 100% at 7 and 30 d after treatment. The essential oil EC formulation initially reduced populations by 68% at 7 d, but control diminished to 2% by 30 d. Results of the field applications and laboratory experiments demonstrate that the β-cyfluthrin EC and fipronil granules provide excellent control of Asian cockroach populations. [ABSTRACT FROM AUTHOR]

Highlights: [•] Let-7, miR-100 and miR-125 expression increases in the last nymph of Blattella germanica. [•] Depletion of these three miRNAs results in subtle defects in wing morphogenesis. [•] Depletion of Broad Complex expression triggers a reduction of these three miRNAs. [Copyright &y& Elsevier]

Abstract: In Drosophila melanogaster, miR-8-3p regulates mRNA levels of atrophin, a factor involved in neuromotor coordination, and we found that Blattella germanica with suppressed atrophin showed motor problems. Bionformatic predictions and luciferase-reporter tests indicated that B. germanica atrophin mRNA contains target sites for miR-8-3p and miR-8-5p. Suppression of miR-8-3p or miR-8-5p appeared to increase atrophin mRNA. The effects of suppression of Argonaute (AGO) 1 or AGO2 expression on miR-8-3p and miR-8-5p suggested that miR-8-3-p might predominantly bind to AGO1, whereas miR-8-5p might bind to a moderate extent to both AGO1 and AGO2 in the respective RNA-induced silencing complexes (RISCs). We propose that the interplay of miR-8-3p, miR-8-5p, AGO1 and AGO2, maintain the appropriate levels of atrophin mRNA. This would be the first example of two strands of the same miRNA precursor regulating a single transcript. [Copyright &y& Elsevier]

During the last decade, multilocus analysis has gradually become a powerful tool for the studies of population genetics and phylogeography. The double-striped cockroach, Blattella bisignata, is endemic to southeast Asia, and there is currently little genetic information available for the species. We chose it as the target species to investigate a biodiversity hotspot in southwest China. Here, we report the identification and characterization of 11 single-copy anonymous nuclear markers with an average length of 378bp. These loci, isolated from a genomic library of B. bisignata, can amplify in two additional Blattella species (B. germanica and B. lituricollis). While testing these markers in representative species of Blattellidae, Blattidae and Epilampridae, some of them can cross-amplify successfully. After sequencing 30 individuals collected from southern China per locus, we found relatively high variability (approximately 3.6 SNPs per 100bp). Finally, a small-scale study was also performed to show that these markers do indeed fulfill the expectations as phylogeographic markers. [ABSTRACT FROM PUBLISHER]

Mulch preferences of the Asian cockroach, Blattella asahinai Mizukubo, were determined in a series of laboratory experiments. Because this species is a peridomestic pest, mulch preferences may be a key part of an integrated pest management program for homeowners. Five mulches were used: cypress, oak leaf litter, pine straw, rubber, and topsoil. Large arena experiments showed that adult male Asian cockroaches preferred oak leaf litter and pine straw, while adult females preferred oak leaf litter and rubber mulches. Nymphal stages preferred rubber (48.3-62.5% for small and medium instars, respectively) to all other mulches. All stages of the Asian cockroach showed very little preference to topsoil (0%) and cypress mulch (6.3%). Ebeling choice box tests confirmed lack of preference or repellency of adult males to topsoil (17.8 ± 3.6%) and rubber mulch (15.7 ± 3.6%). Continuous exposure experiments indicated that pine straw was significantly more toxic to adult males than other mulches (66.7 ± 18.4% mortality at 7 d). Mulch preferences of the Asian cockroach may be mediated by characteristics of the interstitial spaces in the different mulches. Rubber mulch afforded smaller, more humid spaces that were inaccessible to adults. Because cypress mulch was least preferred by nymphs and adults, use of cypress mulch in an integrated pest management program around homes may help to reduce Asian cockroach populations and limit insecticide exposure to humans, animals, and the environment. [ABSTRACT FROM AUTHOR]

Dicer-2 is a ribonuclease involved in the insect RNAi pathway. On attempting to knockdown Dicer-2 expression in the insect Blattella germanica by RNAi, we found that treatment with Dicer-2 dsRNA upregulated the targeted mRNA. This unexpected result was also observed after treating with a nucleopolyhedrovirus dsRNA. Experiments with this alien dsRNA showed an all-or-none response with a threshold for inducing Dicer-2 upregulation between 0.4 and 0.04 μg in terms of dsRNA concentration and between 50 and 20 bp in terms of dsRNA length. The response seems specific of dsRNA given that equivalent experiments carried out with dsDNA did not affect Dicer-2 expression. In insects, Dicer-2 is postulated to be a sensor of viral infections and a key antiviral defense element. The upregulation of Dicer-2 expression after dsRNA administration fits well with this sensor role, and the occurrence of this mechanism in B. germanica, a phylogenetically basal insect, suggests that sensing alien RNAs might be an ancestral function of Dicer-2 proteins. [ABSTRACT FROM AUTHOR]

Background: Previous work showed that miRNAs play key roles in the regulation of metamorphosis in the hemimetabolan species Blattella germanica. To gain insight about which miRNAs might be important, we have constructed two miRNA libraries, one of the penultimate, pre-metamorphic nymphal instar (N5) and the other of the last, metamorphic nymphal instar (N6). Results: High throughput sequencing gave 61 canonical miRNAs present in the N5 and N6 libraries, although at different proportions in each. Comparison of both libraries led to the identification of three and 37 miRNAs significantly more expressed in N5 and N6 respectively. Twelve of these 40 miRNAs were then investigated further by qRT-PCR and results indicated that miR-252-3p was well expressed in N5 but not in N6, whereas let-7-5p, miR-100-5p and miR-125-5p showed the reverse pattern. 20-Hydroxyecdysone (20E) tended to stimulate miRNA expression, whereas juvenile hormone (JH) inhibited the 20E stimulatory effect. Expression of let-7, miR-100 and miR-125 was increased by 20E, which has also been observed in D. melanogaster. The only miRNA that was inhibited by 20E was miR-252-3p. The involvement of let-7, miR-100 and miR-125 in metamorphosis has been demonstrated in other insects. Depletion of miR-252-3p caused growth and developmental delays, which suggests that this miRNA is involved in regulating these processes prior to metamorphosis. Conclusions: The comparative analysis of miRNA libraries from pre-metamorphic (N5) and metamorphic stages (N6) of B. germanica proved to be a useful tool to identify miRNAs with roles in hemimetabolan metamorphosis. Three miRNAs emerged as important factors in the metamorphic stage (N6): let-7-5p, miR- 100-5p and miR-125-5p, whereas miR-252-3p appears to be important in the pre-metamorphic stage (N5). [ABSTRACT FROM AUTHOR]

The ribosomal DNA (rDNA) cluster of insects contains several hundred repeating structural-functional units and, therefore, is a typical example of a multigene family. Eukaryotic ribosomal RNA (rRNA) genes (18S, 5.8S, and 28S like) are arranged in tandemly repeated clusters in the nucleolus organizers, separated by several spacers, namely the nontranscribed spacer, the external transcribed spacer (ETS), and the internal transcribed spacers. The nucleotide sequences of the ETS of the three closely related Blattella cockroach species, Blattella germanica (Linnaeus, 1767), Blattella asahinai (Mizukubo, 1981), and Blattella lituricollis (Walker, 1868), were determined and compared. The three species had relatively similar ETS lengths, and sequence differences among them could be explained by two types of rearrangements, namely deletions of subrepeats and nucleotide substitutions. Minor ETS variants in B. germanica differed from the major variant in the same way that the major ETS variants of the three Blattella species differed from each other. Concerted evolution and the birth-and-death models, which are often invoked to explain the diversity and evolution of the multigene families of rDNA clusters, are discussed in the light of our data. A new model is proposed to explain the evolutionary reorganization of the ETS region: evolution of rDNA by 'magnification-and-fixation' is characterized by magnification of minor subrepeats, which become adaptive in a new rapidly changed environment, and subsequent fixation of this variant type as a major component of the multigene family of a new species. L'amas d'ADN ribosomique (ADNr) chez les insectes compte plusieurs centaines d'unités fonctionnelles répétées et constitue, par le fait même, un exemple typique d'une famille multigénique. Les gènes (de type 18S, 5,8S et 28S) qui codent pour les ARN ribosomiques (ARNr) sont disposés en tandem au sein des organisateurs nucléolaires et sont séparés par des espaceurs dont l'espaceur non-transcrit, l'espaceur externe transcrit (ETS) et des espaceurs internes transcrits. Les séquences nucléotidiques des ETS chez trois espèces proches de blattes du genre Blattella (Blattella germanica (Linnaeus, 1767), Blattella asahinai (Mizukubo, 1981) et Blattella lituricollis (Walker, 1868)) ont été déterminées et comparées. Les trois espèces possédaient des ETS de tailles semblables et les différences de séquences entre elles pouvaient s'expliquer au moyen de deux types de réarrangements, soit des délétions de sous-répétitions ou des substitutions nucléotidiques. Des variants ETS mineurs chez le B. germanica différaient du variant majeur de la même manière que les variants majeurs différaient entre eux au sein des trois espèces. À la lumière des résultats obtenus, les auteurs discutent des modèles d'évolution concertée et de naissance-mort, lesquels sont souvent invoqués pour expliquer la diversité et l'évolution des amas multigéniques d'ADNr. Un nouveau modèle est proposé pour expliquer la réorganisation de la région ETS au cours de l'évolution. L'évolution de l'ADNr par « multiplication et fixation » est caractérisée par une multiplication de sous-répétitions mineures, lesquelles deviennent avantageuses dans le contexte d'un environnement récemment modifié, suivie de la fixation de ce type variant en tant que composante majeure au sein de la famille multigénique chez une nouvelle espèce. [ABSTRACT FROM AUTHOR]

Two acetylcholinesterases (AChEs; BgAChE1 and BgAChE2) from Blattella germanica were functionally expressed using the baculovirus system. Kinetic analysis demonstrated that BgAChE2 had higher catalytic efficiency but lower substrate specificity than BgAChE1. With the exceptions of paraoxon and propoxur, BgAChE1 was generally less sensitive to inhibitors than BgAChE2. Western blot analysis using anti-BgAChE antibodies revealed that BgAChE1 was far more abundant in all examined tissues compared to BgAChE2, which is only present in the central nervous system. Both BgAChEs existed in dimeric form, covalently connected via a disulphide bridge under native conditions. Most fractions of BgAChE1 had a glycophosphatidylinositol (GPI) anchor, but a small fraction comprised a collagen-like tail. BgAChE2 appeared to have a collagen-GPI-fused tail. Based on the kinetic and molecular properties, tissue distribution and abundance, BgAChE1 was confirmed to play a major role in postsynaptic transmission. [ABSTRACT FROM AUTHOR]

Responses of German cockroaches, Blattella germanica (L.) (Dictyoptera: Blattelli- dae),to microencapsulated (ME) formulations of six insecticides (bifenthrin, chlorpyrifos, cyfluthrin, deltamethrin, lambda-cyhalothrin, and permethrin) were compared with emulsifiable concentrates (EC) (chiorpyrifos, cyfluthrin, deltaniethrin, and permethrin) or ready-to-use (RTU) formulations (bifenthin and lambda-cyhalothrin). Two rates were tested per comparison. Baseline toxicity (LT50 value) was determined by continuous exposure to residual deposits. Repellency, toxicity (LT50), and performance index (PI) values were determined using Ebeling choice boxes. Baseline toxicity of the permethrin formulations was similar, but all other active ingredients had significant toxicity differences at one or both formulation X dose comparisons. Baseline toxicity and repellency were negatively correlated. Choice box LT50 and the time to reach 50% of the maximum PI were positively correlated. The maximum PI was positively correlated (P < 0.06) with baseline LT50 and negatively correlated (P < 0.07) with repellency. Chlorpyrifos had the lowest repellency except for the EC at 0.25%. Bifenthrin ME and lambda-cyhalothrin ME had greater PI values than comparative RTU formulations. Cyfluthrin EC at 0.03% and deltamethrin ME at 0.01% had significantly lower PI values than comparison treatments. Permethrin PI value for the EC at 0.03% exceeded that for the ME, but at 0.05% the ME had a significantly greater PI. These data demonstrate the difficulty in making generalizations about the relative performance of ME compared with EC or RTU formulations. Variable results observed within, and between, formulations may be influenced by application rate, formulation type, other formulation components, and the toxicity-repellency of the active ingredient. [ABSTRACT FROM AUTHOR]

Abstract: The Broad-Complex (BR-C) is a primary response gene in the ecdysteroid signaling pathway which encodes a family of transcription factors that play a key role in metamorphic processes. With the aim of studying the possible functions of BR-C in the embryogenesis of a short germ band insect, we cloned BR-C cDNAs in the cockroach Blattella germanica (BgBR-C) and obtained the full coding region of six BR-C isoforms (Z1–Z6) of which, Z1–Z5 have homologous sequences in other insects, whereas Z6 is new. Temporal-expression patterns indicate that BgBR-C isoforms are present throughout the embryogenesis of B. germanica, although with weak fluctuations. Silencing all BgBR-C isoforms in the embryo through parental RNAi elicited a diversity of phenotypes. These phenotypes suggest roles for BgBR-C in different embryogenesis processes of B. germanica, mainly in the formation of the germ band, in the transition from 30% to 35% of total development, when the amnion and serosa rupture and the secondary dorsal organ is formed, and in the hatching process, which involves neural, endocrine and muscular coordination. [Copyright &y& Elsevier]

How does a juvenile insect transform into an adult? This question. which sums up the wonder of insect metamorphosis, has fascinated mankind since ancient times. Modern physiology has established the endocrine basis regulating these transformations, which mainly depend on two hormone types: ecdysteroids, which promote molts, and juvenile hormones, which repress the transformation into the adult stage. The interplay of these two hormones regulates the genes involved in juvenile and adult programs and the shift from one to the other. microRNAs (miRNAs) are small noncoding RNA5, which participate in many biological processes, and we wondered whether they might be also involved in insect metamorphosis. In insects, Dicer-1 ribonuclease transforms miRNA precursors into mature miRNAs. Thus, using systemic RNA interference (RNAi) to silence the expression of Dicer-i in the hemimetabolan insect Blattella germanica, we depleted miRNA contents in the last instar nymph. This practically inhibited metamorphosis after the next molt, as the resulting specimens showed nymphoid features and were able to molt again. The experiments show that miRNAs play a key role in hemimetabolan metamorphosis, perhaps regulating genes that are juvenile hormone targets. [ABSTRACT FROM AUTHOR]

The city-wide distribution of the Asian cockroach, Blattella asahinai Mizukubo, was determined in Dothan, Alabama in 2008. Surveys were conducted in the summers of 2004 and 2008 and consisted of site visits to all city parks and municipal facilities as well as a number of home, business, and municipal landscapes. Asian cockroaches were found at 95.1% of the locations we examined in 2008. Several sites were sampled at most locations for a total of 65 sites. The elevation of sites with Asian cockroaches was 114.00 ± 5.76 m (mean ± SD) above sea level. Of the 63 sites with Asian cockroaches, the cockroaches were found in pine straw at 36 (57.1%) sites and in oak leaf litter at 23 (36.5%) sites. Based on this survey, we conclude that the Asian cockroach is distributed throughout the city of Dothan. [ABSTRACT FROM AUTHOR]

The toxicity of fatty acid salts to German, Blattella germanica (L.), and American cockroaches, Periplaneta americana (L.), was evaluated. Potassium and sodium laurate caused up to 95% mortality of German cockroaches and 100% mortality of American cockroaches. Even-numbered potassium fatty acid salts, C8-C18 were assessed for toxicity at 0.125, 0.25, 0.5, 1, and 2% concentrations by a 30-s immersion of cockroaches. The more soluble of the fatty acid salts at 2% concentration caused 65-95% mortality of German cockroaches and 100% mortality of American cockroaches. Potassium oleate, C18, was most toxic to both German (LC50 = 0.36%) and American (LC50 = 0.17%) cock- roaches. Fatty acid salt solutions on a substrate were tested by placing cockroaches in contact with treated floor tiles immediately after application (wet) or after the solutions had dried. Sodium laurate and potassium caprate caused mortality of German (62 ± 17.4 and 58 ± 12.6%, respectively) and American cockroaches (52 ± 18.5 and 28 ± 4.9%, respectively) on wet tiles, whereas potassium oleate caused mortality of German cockroaches (67 ± 14.1%) only. Dry fatty acids caused no mortality among exposed cockroaches. Fatty acid salt solutions can be effective in killing German and American cockroaches but only when insects are thoroughly wetted with 1-2% fatty acid salt solutions. [ABSTRACT FROM AUTHOR]

Large numbers of a cockroach that resembled the German cockroach, Blattella germanica (L.), were observed during winter 2005-2006 in home turf settings in Weslaco, TX, 11 km from the U.S. border with northeastern Mexico. 111 June and July 2006, this cockroach was observed at night on the foliage of soybean, Glycine max (L.) Merr., in numbers often exceeding 50 per m row. Because of its similarity to B. germanica, but with the characteristic of flying frequently, we suspected that our observations might be of the Asian cockroach, Blattella asahinai Mizukubo. Using a combination of morphological characters, cuticular hydrocarbons, and sequences of the mitochondrial cytochrome oxidase II gene, we definitively identified this cockroach as B. asahinai. B. asahinai was frequently observed feeding on sentinel eggs of Helicoverpa zea (Boddie) and Spodoptera exigua (Hübner). This cockroach was the dominant egg predator in soybean during 2006, making up 36.4% of all predators observed feeding on eggs. B. asahinai was only observed occupying the soybean canopy nocturnally, and it made up 53.7% of predators observed feeding at night. We speculate that B. asahinai may serve as an important beneficial insect in soybean and other crops. [ABSTRACT FROM AUTHOR]

The Asian cockroach, Blattella asahinai Mizukubo (Dictyoptera: Blattellidae), was discovered in large numbers in southeastern Alabama in 2003. We surveyed southern Alabama and Georgia to determine the distribution of this species. In total, 67 of the 159 counties in Georgia and 33 counties of the 67 counties in Alabama were sampled. We found that B. asahinai was established in seven counties in Georgia and eight counties in Alabama. The area that B. asahinai has colonized in Alabama is double that of Georgia. The distribution of B. asahinai closely follows major highways and interstates, and it has likely expanded its range by using human transportation. Cold temperatures and suitable habitats are probably the only factors limiting the range of B. asahinai. [ABSTRACT FROM AUTHOR]

For the first time, extended fragments (5′-truncated copies) of R1 and R2 retrotransposons integrated into the Blattella germanica genome were identified, cloned, and sequenced. Structural comparison of the clones revealed two distinct R1 subfamilies. However, all R1 clones had two common features: poly(T) tails and similar target site duplications. R1 retrotransposons are the first known mobile elements with poly(T) tails on the 3′-ends. The structure and nucleotide sequences of five sequenced R2 fragments were similar to each other. Nucleotide sequence analysis of R2 retrotransposons revealed typical deletions at the 3′ ends of the target sites and the lack of homopolynucleotide tails. [ABSTRACT FROM AUTHOR]

The cytotoxic effects of blattellaquinone (BTQ), a sex pheromone produced by adult female German cockroaches, have been studied using human lung adenocarcinoma A549 cells. 1,4-Benzoquinone (BQ), a toxic chemical implicated in benzene toxicity, was used as a reference compound. Both BQ and BTQ showed comparable toxicity toward A549 cells, with LD50values estimated to be 14 and 19 M, respectively. These two compounds increased the formation of an oxidized fluorescent probe, 2‘,7‘-dichlorofluorescein, but had no effect on the cellular GSSG level. Interestingly, BTQ increased the level of 8-epi-prostaglandin F2and was 4-fold more efficient in depleting cellular GSH content than BQ. Of the five GSH adducts of BTQ isolated, three were identified as mono-GSH conjugates, and the other two were di-conjugates. Mass spectrometric and NMR analyses of the di-conjugates showed that the second GSH molecule displaced the isovaleric acid moiety, potentially via a nucleophilic substitution reaction. The ability of BTQ to conjugate a second GSH molecule without quinone regeneration indicated that it may be a more effective cross-linking agent than BQ. Future experiments may be needed to evaluate the overall safety of BTQ before the commercialization of the compound as a cockroach attractant. [ABSTRACT FROM AUTHOR]

The energetic cost of a sublethal treatment with chlorpyrifos was estimated by use of direct microcalorimetry to measure metabolic heat in susceptible and resistant strains of the German cockroach Blattella germanica L. Moreover, one of the detoxification enzyme systems known to be involved in detoxification of chlorpyrifos, glutathione-S-transferase, was measured. Individual cockroaches were exposed for 20 rain on a glass-surfaces treated with 1.14 μg/cm² of chlorpyrifos. There was no difference in glutathione-S-transferase activity of susceptible or resistant strains after the treatment. The heat production increased in the susceptible strain ≈30 min after exposure and declined again after ≈120 min to the basal level. The energetic cost of the exposure to the insecticide corresponds ≈5 h of normal metabolism. There were no significant differences in heat production after toxic treatment in any of the resistant strains. It was shown that measurement of heat production is a sensitive method to prove toxic reactions after exposure to a low dose of insecticide. The use of microcalorimetry as a promising biomarker technology was shown. [ABSTRACT FROM AUTHOR]

During vitellogenesis, one of the most tightly regulated processes in oviparous reproduction, vitellogenins are incorporated into the oocyte through vitellogenin receptor (VgR)-mediated endocytosis. In this paper, we report the cloning of the VgR cDNA from Blattella germanica, as well as the first functional analysis of VgR following an RNA interference (RNAi) approach. We characterized the VgR, VgR mRNA and protein expression patterns in pre-adult and adult stages of this cockroach, as well as VgR immunolocalization in ovarioles, belonging to the panoistic type. We then specifically disrupted VgR gene function using RNAi techniques. Knockdown of VgR expression led to a phenotype characterized by low yolk content in the ovary and high vitellogenin concentration in the haemolymph. This phenotype is equivalent to that of the yolkless mutant of Drosophila melanogaster, which have the yl ( VgR) gene disrupted. The results additionally open the perspective that development genes can be functionally analyzed via systemic RNAi in this basal species. [ABSTRACT FROM AUTHOR]

This study compared an integrated pest management (IPM) program with conventional, calendar-based pest control in nine North Carolina elementary schools. Both programs primarily targeted the German cockroach, Blattella gennanica (L.). The IPM program relied heavily on monitoring and baiting, whereas the conventional approach used baseboard and crack-and-crevice sprays of insecticides. Within the constraints of an existing pest management contract, we quantified service duration, materials used, cost, levels of cockroach infestation, and the pesticide residues generated by the two service types. IPM services were significantly more time-consuming than conventional services, resulting in a significantly higher cost associated with labor. Nevertheless, the two types of treatments incurred similar total costs, and the efficacy of both treatments was also similar. Most importantly, pest monitoring, a central element of the IPM program, revealed few cockroaches and indicated that most of the conventional treatments were unnecessary. Environmental residues of the organophosphate pesticides acephate, chlorpyrifos, and propetamphos were significantly higher in swab samples taken in the conventionally treated schools. This study demonstrates that an IPM program is an appropriate and preferable alternative to conventional methods of pest control in the school environment. [ABSTRACT FROM AUTHOR]

Carbon dioxide anaesthesia differentially affects the knockdown and recovery of cockroaches, depending on the strain and the length of time that the colony has been subjected to a CO2 regime. Adult males from two laboratory and two field-collected strains of German cockroaches,Blattella germanica, are knocked down within 7–45 s after exposure to CO2. After 5 min of CO2 exposure, presumptive recovery (i.e. the time for the cockroach to right itself after knockdown) for laboratory strains occurs significantly sooner than for field-collected strains. Control cockroaches, exposed to compressed air rather than CO2, exit harbourage cups rapidly (≤3.20 min). However, although allowed a recovery period of 5 min, significant movement impairment occurs for all cockroach strains anaesthetized with CO2. Carbon dioxide exposure significantly reduces consumption of 2.15% hydramethylnon bait and delays mortality even when 24 h is allowed for recovery before bait placement. Cockroaches allowed to recover for 48 h after 5 min of CO2 exposure consume significantly more bait and die significantly faster than CO2 exposed groups allowed 24 h of recovery, and mortality is not significantly different from nonanaesthetized bait-fed controls. [ABSTRACT FROM AUTHOR]

The polymorphism of nuclear ribosomal DNA has been studied in male German cockroaches. The RFLP analysis has been used to identify seven types of HindIII fragments, the variation of which may serve as the basis for the differentiation of laboratory strains with respect to some population indices, including the average number of fragments per animal ( N), the proportion of polymorphic loci ( P), and the average pairwise similarity (APS). The interpopulation variation ( FST) calculated for nine haplotypes is 53.85%. [ABSTRACT FROM AUTHOR]

The mevalonate pathway in insects has two important peculiarities, the absence of the sterol branch and the synthesis of juvenile hormone (JH), that may have influenced the mechanisms of regulation. The data available on these mechanisms indicate that cholesterol does not play a regulatory role and that JH modulates transcript levels of a number of genes of the mevalonate pathway or can influence the translatability and/or stability of the transcripts themselves. These data suggest that the mevalonate pathway in insects can best be interpreted in terms of coordinated regulation, in which regulators act in parallel to a number of enzymes, as occurs in the cholesterol-driven pathway in vertebrates. [ABSTRACT FROM AUTHOR]

Aggregation is widespread in invertebrate societies and can appear in response to environmental heterogeneities or by attraction between individuals. We performed experiments with cockroach, Blattella germanica, larvae in a homogeneous environment to investigate the influence of interactions between individuals on aggregations. Different densities were tested. A first phase led to radial dispersion of larvae in relation to wall-following behaviours; the consequence of this process was a homogeneous distribution of larvae around the periphery of the arena. A second phase corresponded to angular reorganization of larvae leading to the formation of aggregates. The phenomenon was analysed both at the individual and collective levels. Individual cockroaches modulated their behaviour depending on the presence of other larvae in their vicinity: probabilities of stopping and resting times were both higher when the numbers of larvae were greater. We then developed an agent-based model implementing individual behavioural rules, all derived from experiments, to explain the aggregation dynamics at the collective level. This study supports evidence that aggregation relies on mechanisms of amplification, supported by interactions between individuals that follow simple rules based on local information and without knowledge of the global structure. [Copyright &y& Elsevier]