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Voltage-gated sodium channels (VGSCs) are essential in cell electrical signal transmission, which controls the initiation and propagation of action potentials between neurons and other excitable cells, and rapid inactivation of sodium channels is critical for electrical signalling. Scorpion toxins act on sodium channels and affect the rapid deactivation rate of the channels. Therefore, it is of great importance to analyze the interaction mechanism between scorpion toxins and sodium channels. By comparing the amino acid sequences of Blattella germanica, Periplaneta americana and mammalian sodium channels, it was found that four different amino acids found are I291L, Y292F, V295N, and L406I. Site-directed mutation technique was used to construct four amino acid mutant plasmids on the B. germanica VGSCs, and Xenopus oocytes were employed as vehicles for gene expression. Electrophysiological results showed that the V295N mutation significantly reduced the sensitivity of the sodium channel to α-scorpion toxin Lqh IT (approximately 21.63 - fold). Further 3D homology modeling and molecular docking of the scorpion toxin revealed that the V295N mutation discovered sodium channel M291 to form a hydrogen bond with the K63 amino acid of LqhαIT, which prevented its binding with LqhαIT. In conclusion, V295N mutation indirectly affected the binding of the channel to LqhαIT, resulting in a reduction in the sensitivity of the channel to LqhαIT. [ABSTRACT FROM AUTHOR]

This study investigated how management strategies influence resistance profiles in German cockroach (Blattella germanica (L.)) populations and their impact on the performance of commercial gel baits containing fipronil, imidacloprid, and indoxacarb. Field populations from premises managed under 3 different strategies: Baiting, random insecticide (RI) used, and insecticide rotation (IR) were tested. Almost all populations under RI and IR were resistant to deltamethrin, but low to moderate resistance was observed under the Baiting approach. Cytochrome P450 monooxygenases (P450) were involved in deltamethrin resistance in these resistant populations. All individuals under Baiting and RI were homozygous for the L993F mutation, but the populations under IR lacked homozygous-resistant individuals. Eighty-three percent of field populations with complete homozygosity for the Rdl mutation displayed low mortality upon exposure to 3× LD95 fipronil.The effect of P450 and the Rdl mutation conferred high fipronil resistance in populations under the Baiting approach, recording moderate performance indices (PI) of 44–67 in fipronil bait. By contrast, those populations under RI and IR, in which involve glutathione S-transferases in fipronil resistance, had high PIs of 78–93. Almost 80% of populations exhibited over 90% mortality at 3× LD95 indoxacarb treatment, accompanied by high PIs of 90–100 in indoxacarb bait. Partial mortality from 1× LD95 imidacloprid occurred across all field populations due to the involvement of P450. PIs of imidacloprid bait ranged 5–57 and 20–94 in populations under RI and IR, respectively. Field populations demonstrate different resistance profiles depending on the treatment regimes, and the resistance mechanisms involved influenced gel bait's effectiveness. [ABSTRACT FROM AUTHOR]

Simple Summary: With rising concerns about traditional chemical insecticides, there is growing interest in safer, natural alternatives. Among these options, essential oils have received special attention. While some essential oils are registered through traditional routes for standard biocides, others are registered as low-risk biocides, as they meet specific criteria for minimal risk. This study evaluates and compares the insecticide efficacy of essential oils against the German cockroach, Blattella germanica, a major and widespread urban pest. Sixteen essential oils, both registered as low-risk biocides and/or standard biocides, were tested in a topical application experiment. The results showed that, while all essential oils tested were toxic to the cockroaches, their effectiveness varied. Thyme, sweet orange, and lavender oils were the most effective, achieving knockdown in less than 30 s and 100% mortality in 24 h. Linseed and cottonseed oils were the least effective, with 24 h mortality rates of 70% and 40%, respectively. Importantly, some of the oils classified as low-risk were just as effective as others classified as standard biocides, thus suggesting that low-risk classification does not necessarily compromise efficacy. These findings underscore the potential of essential oils as bioinsecticides, emphasizing the importance of considering both insecticidal performance with low-risk attributes. Concerns about the negative effects of traditional insecticides and increasing insecticide resistance have prompted the exploration of botanical alternatives like essential oils (EOs). The registration of biocides is a mandatory procedure, and some regions have established a special status for compounds that meet specific low-risk criteria, which includes certain EOs. This study aimed to evaluate and compare the efficacy of sixteen EOs, both registered as low-risk biocides and/or standard biocides, against the German cockroach, Blattella germanica. A topical application was performed with undiluted EOs (15 µL) on the dorsal surface of awake cockroaches. The results showed significant variations in efficacy, as follows: thyme, sweet orange, and lavender oils were the most effective, achieving 100% mortality within 24 h and a less than 30 s knockdown effect. In contrast, linseed and cottonseed oils were the least effective, resulting in 70% and 40% 24 h mortality. Remarkably, some EOs registered as low-risk biocides performed as well as the ones registered as standard biocides, suggesting that this category does not have to always be at odds with efficacy. Future research should adopt practical, application-driven approaches to ensure bioinsecticides balance performance and safety, meeting both regulatory and consumer demands. [ABSTRACT FROM AUTHOR]

Abstract Background The overuse of antibiotics has led to lethal multi-antibiotic-resistant microorganisms around the globe, with restricted availability of novel antibiotics. Compared to conventional antibiotics, evolutionarily originated antimicrobial peptides (AMPs) are promising alternatives to address these issues. The gut microbiome of Blattella germanica represents a previously untapped resource of naturally evolving AMPs for developing antimicrobial agents. Results Using the in-house designed tool “AMPidentifier,” AMP candidates were mined from the gut microbiome of B. germanica, and their activities were validated both in vitro and in vivo. Among filtered candidates, AMP1, derived from the symbiotic microorganism Blattabacterium cuenoti, demonstrated broad-spectrum antibacterial activity, low cytotoxicity towards mammalian cells, and a lack of hemolytic effects. Mechanistic studies revealed that AMP1 rapidly permeates the bacterial cell and accumulates intracellularly, resulting in a gradual and mild depolarization of the cell membrane during the initial incubation period, suggesting minimal direct impact on membrane integrity. Furthermore, observations from fluorescence microscopy and scanning electron microscopy indicated abnormalities in bacterial binary fission and compromised cell structure. These findings led to the hypothesis that AMP1 may inhibit bacterial cell wall synthesis. Furthermore, AMP1 showed potent antibacterial and wound healing effects in mice, with comparable performances of vancomycin. Conclusions This study exemplifies an interdisciplinary approach to screening safe and effective AMPs from natural biological tissues, and our identified AMP 1 holds promising potential for clinical application. Graphical Abstract Video Abstract

Background: The overuse of antibiotics has led to lethal multi-antibiotic-resistant microorganisms around the globe, with restricted availability of novel antibiotics. Compared to conventional antibiotics, evolutionarily originated antimicrobial peptides (AMPs) are promising alternatives to address these issues. The gut microbiome of Blattella germanica represents a previously untapped resource of naturally evolving AMPs for developing antimicrobial agents. Results: Using the in-house designed tool "AMPidentifier," AMP candidates were mined from the gut microbiome of B. germanica, and their activities were validated both in vitro and in vivo. Among filtered candidates, AMP1, derived from the symbiotic microorganism Blattabacterium cuenoti, demonstrated broad-spectrum antibacterial activity, low cytotoxicity towards mammalian cells, and a lack of hemolytic effects. Mechanistic studies revealed that AMP1 rapidly permeates the bacterial cell and accumulates intracellularly, resulting in a gradual and mild depolarization of the cell membrane during the initial incubation period, suggesting minimal direct impact on membrane integrity. Furthermore, observations from fluorescence microscopy and scanning electron microscopy indicated abnormalities in bacterial binary fission and compromised cell structure. These findings led to the hypothesis that AMP1 may inhibit bacterial cell wall synthesis. Furthermore, AMP1 showed potent antibacterial and wound healing effects in mice, with comparable performances of vancomycin. Conclusions: This study exemplifies an interdisciplinary approach to screening safe and effective AMPs from natural biological tissues, and our identified AMP 1 holds promising potential for clinical application. Bfzw53yZZxeQJxRuWThBYF Video Abstract [ABSTRACT FROM AUTHOR]

Cockroaches, ubiquitous pests known for significant reproduction and as potential vectors of diseases, are notorious for their adoptability to a variety of insecticides that cause substantial challenges in pest control. The present research evaluated the LC50 concentrations of imidacloprid (0.65 mg/L) and clothianidin (2.5 μg/L) for Blattella germanica using topical and bait methods. The cockroaches were exposed to one‐third concentration of LC50 at a regular interval of 1, 2, 4, 8, 12, 16 and 20 days. During exposure, the activity of P450 monooxygenase increased, whereas the activity of brain acetylcholinesterase decreased. Lactate dehydrogenase, alkaline and acid phosphatase activity were highest on day 4, with a slight recovery on day 20. The elevated activities for superoxide dismutase and catalase, as well as increased lipid peroxidation levels on day 4, followed by a significant recovery in activity on day 20. The glutathione‐S‐transferase activity was elevated while the glutathione content was reduced, and a significant restoration was observed at the end of the experiment. The biochemical mechanisms of the organisms such as P450, esterase enzymes and oxidative systems, are actively involved in the detoxification mechanism. The study elucidated that the insecticide defence mechanism triggers detoxification pathways that encompass the metabolism of endogenous insecticidal compounds, with clothianidin showing greater efficacy and lower detoxification compared with imidacloprid. [ABSTRACT FROM AUTHOR]

Insect cuticular hydrocarbons (CHCs) serve as important waterproofing barriers and as signals and cues in chemical communication. Over the past 30 years, numerous studies on CHCs have been conducted in the German cockroach, Blattella germanica, leading to substantial progress in the field. However, there has not been a systematic review of CHC studies in this species in recent years. This review aims to provide a concise overview of the chemical composition, storage, transport, and physical properties of different CHCs in B. germanica. Additionally, we focus on the biosynthetic pathway and the genetic regulation of HC biosynthesis in this species. A considerable amount of biochemical evidence regarding the biosynthetic pathway of insect CHCs has been gathered from studies conducted in B. germanica. In recent years, there has also been an improved understanding of the molecular mechanisms that underlie CHC production in this insect. In this article, we summarize the biosynthesis of different classes of CHCs in B. germanica. Then, we review CHCs reaction to various environmental conditions and stressors and internal physiological states. Additionally, we review a body of work showing that in B. germanica, CHC profiles exhibit significant sexual dimorphism, specific CHCs act as essential precursors for female contact sex pheromone components, and we summarize the molecular regulatory mechanisms that underlie sexual dimorphism of CHC profiles. Finally, we highlight future directions and challenges in research on the biosynthesis and regulatory mechanisms of CHCs in B. germanica, and also identify potential applications of CHC studies in the pest control. [ABSTRACT FROM AUTHOR]

Termites, together with cockroaches, belong to the Blattodea. They possess an XX/XY sex determination system which has evolved from an XX/X0 system present in other Blattodean species, such as cockroaches and wood roaches. Little is currently known about the sex chromosomes of termites, their gene content, or their evolution. We here investigate the X chromosome of multiple termite species and compare them with the X chromosome of cockroaches using genomic and transcriptomic data. We find that the X chromosome of the termite Macrotermes natalensis is large and differentiated showing hall marks of sex chromosome evolution such as dosage compensation, while this does not seem to be the case in the other two termite species investigated here where sex chromosomes may be evolutionary younger. Furthermore, the X chromosome in M. natalensis is different from the X chromosome found in the cockroach Blattella germanica indicating that sex chromosome turn-over events may have happened during termite evolution. [ABSTRACT FROM AUTHOR]

Introduction: This study aimed to analyze the types and distribution characteristics of major inhalant allergens in patients with allergic rhinitis (AR) in Yinchuan, China. Methods: In this cross-sectional study, 2,000 outpatients suspected of having AR were included from 2022 to 2023 at the Department of Otolaryngology-Head and Neck Surgery, General Hospital of Ningxia Medical University. Skin prick tests were performed on the included individuals using 13 common inhalant allergens: house dust mites, dust mites, tropical mites, Artemisia, dog hair, ragweed, cat hair, grass pollen, tree pollen, mold group I, mold group IV, German cockroach (Blattella germanica), and American cockroach (Periplaneta americana). The results of the skin prick tests were summarized, and patients with positive results were grouped by ethnicity, gender, and age to compare the differences in the positive rates of various inhalant allergens between the groups. The number of patients visiting each month was recorded to analyze the temporal variation in the incidence rate and compare the differences in the main inhalant sensitizers among patients in each quarter. Results: Among the 2,000 included patients, there were 1,060 males and 940 females, with an average age of 18.7 years. Among the 2,000 outpatients who underwent allergen skin prick tests, 1,346 cases (67.30%) had positive results. The inhalant allergens were ranked in descending order of positive rates as follows: Artemisia (53.25%), dust mites (51.10%), house dust mites (49.10%), ragweed (45.70%), tropical mites (43.15%), dog hair (19.20%), cat hair (16.05%), American cockroach (12.10%), German cockroach (11.25%), grass pollen (9.15%), tree pollen (7.10%), mold group I (6.10%), and mold group IV (5.05%). There were no statistically significant differences in positive rates between different ethnicities or genders (all p > 0.05). Compared to patients aged 18 years and above, patients under 18 years old had statistically significant differences in positive rates for dust mites, Artemisia, ragweed, mold group I, and German cockroach (all p < 0.05). The seasonal distribution indicated that autumn had the highest number of patient visits in a year (579 cases, 58.95%). Conclusion: Artemisia and dust mites were the major inhalant allergens in patients with suspected AR in Yinchuan, China. The positive rate of inhalant allergen skin prick tests was not correlated with the ethnicity or gender of the local population. Autumn was the season with the highest frequency of visits by patients with suspected AR. [ABSTRACT FROM AUTHOR]

Introduction: Sensitivity to indoor allergens increases the risks of asthma and the emergence of allergic diseases. Indoor allergens include house dust mite (HDM), pet dander, cockroach (CR), and molds. We investigated how CR sensitivity was affected during the pandemic period. Methods: This study included patients aged ≥18 years who visited the allergy unit of our clinic between March 2018 and March 2022 and who underwent skin prick tests (SPTs) for aeroallergens. Patients were divided into two groups: those of the prepandemic and pandemic periods, depending on the visit dates. Results: In all, 7,687 patients were recruited; 5,074 individuals with negative SPT results were excluded. Among the 2,613 atopic patients, CR sensitivity was detected in 278 (10.6%). The prevalence of CR sensitivity was significantly higher in the pandemic group than in the prepandemic group (12% vs. 8.6%; p < 0.05). The frequency of asthma was higher in patients with CR sensitivity than in others (33.1% vs. 26%, p = 0.011). In addition, individuals with CR sensitivity were older than others (p = 0.001). CR sensitivity was more common in males than in females (44.2% vs. 37.7%, p = 0.034). Moreover, dog and HDM sensitivities were more common in individuals with CR sensitivity than in others (p = 0.004, p < 0.001, respectively). Conclusion: This study reveals an increased sensitivity to CR during the pandemic and establishes an association between such sensitivity and the frequency of asthma. Variability in terms of CR sensitivity across different countries is emphasized. In addition, HDM and dog sensitivities were more common in individuals with CR sensitivity. [ABSTRACT FROM AUTHOR]

Globalization has facilitated the introduction and establishment of organisms beyond their natural ranges, leading to significant ecological and economic consequences. While many non‐native species are well documented, others remain understudied, either due to their unknown impact or morphological similarities with native species. This study addresses such a case, focusing on synanthropic cockroaches within the order Blattodea. Despite the order's diversity, less than 1% of known species are recorded in urban environments. While certain species like Periplaneta americana, Blatta orientalis and Blattella germanica are well distributed and studied, others remain largely unknown. This research unveils the first established population of Nauphoeta cinerea in Europe, specifically in Spain (Asturias, northern Iberian Peninsula), with specific genetic and morphological confirmation. This study also explores potential pathways of introduction for N. cinerea. Long‐distance transport by ships or escape/release from captivity are proposed as potential pathways for the newly established populations in Asturias. The species' high fecundity and parthenogenetic reproduction raise concerns about its potential invasiveness. Additionally, this study includes unpublished data on various synanthropic cockroaches in Asturias (with the first records of P. lateralis and Supella longipalpa for this area), drawn from specimens deposited in biological collections and some extra collections. An identification key for all Spanish non‐native synanthropic cockroach species is provided to assist in future detections. This research emphasizes the imperative need for robust monitoring systems, highlights the scarcity of scientific information regarding synanthropic cockroach distribution and underscores the pivotal role of biological collections in advancing our understanding of invasive species. [ABSTRACT FROM AUTHOR]

Background: Half of U.S. households own a dog despite 10% of individuals being sensitized to dog. Assessment and treatment options for dog allergy include the use of commercial dog extracts which have inconsistent performance, making diagnosing and managing dog allergy challenging. Contamination of dog extracts with other allergens has previously been reported. Objective: We sought to determine whether commercial dog extracts contain other aeroallergens. Methods: An extract purity and quantification study on acetone precipitated dog hair and dander extract (AP dog) was performed, 6 aeroallergens; Alternaria (Alt a 1), Ragweed (Amb a 1), German Cockroach (Bia g 2), Dust Mite (Der p t), Cat (Fel d 1), and Rye Grass (Lol p 1). Following, conventional dog hair and dander extract (CV dog) and the new ultrafiltered dog hair and dander extract (UF dog) were also assessed based on the initial results ofAP dog. SDS-PAGE was performed on all three dog extracts to compare allergen content. Lastly, serology results and aeroallergen immunotherapy prescriptions were compared. Results: The ELISA trays with Alt a 1, Amb a 1, Bia g 2, Der p 1, and Lol p 1 antibodies did not capture AP dog, while the ELISA tray with Fel d 1 antibody captured AP dog, CV dog, and UF dog. SDS-PAGE residts of the 3 dog extracts did not reveal a band at the molecular weight for Fel d 1. Conculsion: Contamination of commercial dog extracts was not found. However, our findings are supportive of commercial dog extracts containing a Fel d 1-like dog allergen that is cross-reactive to Fel d 1. Cross-reactivity between commercial dog extracts and Fel d 1 could be responsible for double positivity to cat and dog in serology. Additional studies are needed to better illustrate this Fel d 1-like dog allergen. [ABSTRACT FROM AUTHOR]

Background: Early embryogenesis is characterized by dramatic cell proliferation and movement. In most insects, early embryogenesis includes a phase called the uniform blastoderm, during which cells evenly cover the entirety of the egg. However, the embryo of the German cockroach, Blattella germanica, like those of many insects within the super order Polyneoptera, does not have a uniform blastoderm; instead, its first cells condense rapidly at the site of a future germband. We investigated early development in this species in order to understand how early gene expression is or is not conserved in these insect embryos with distinct early cell behaviors. Results: We present a detailed time series of nuclear division and distribution from fertilization through germband formation and report patterns of expression for the early patterning genes hunchback, caudal, and twist in order to understand early polarization and mesoderm formation. We show a detailed time course of the spatial expression of two genes involved in the segmentation cascade, hedgehog and even-skipped, and demonstrate two distinct dynamics of the segmentation process. Conclusions: Despite dramatic differences in cell distribution between the blastoderms of many Polyneopteran insects and those of more well-studied developmental models, expression patterns of early patterning genes are mostly similar. Genes associated with axis determination in other insects are activated relatively late and are probably not maternally deposited. The two phases of segmentation—simultaneous and sequential—might indicate a broadly conserved mode of morphological differentiation. The developmental time course we present here should be of value for further investigation into the causes of this distinct blastoderm type. [ABSTRACT FROM AUTHOR]

Ecdysone-induced protein 93 (E93), known as the 'adult-specifier' transcription factor in insects, triggers metamorphosis in both hemimetabolous and holometabolous insects. Although E93 is conserved in ametabolous insects, its spatiotemporal expression and physiological function remain poorly understood. In this study, we first discover that, in the ametabolous firebrat Thermobia domestica, the previtellogenic ovary exhibits cyclically high E93 expression, and E93 mRNA is broadly distributed in previtellogenic ovarioles. E93 homozygous mutant females of T. domestica exhibit severe fecundity deficiency due to impaired previtellogenic development of the ovarian follicles, likely because E93 induces the expression of genes involved in ECM (extracellular matrix)-receptor interactions during previtellogenesis. Moreover, we reveal that in the hemimetabolous cockroach Blattella germanica, E93 similarly promotes previtellogenic ovarian development. In addition, E93 is also essential for vitellogenesis that is necessary to guarantee ovarian maturation and promotes the vitellogenesis-previtellogenesis switch in the fat body of adult female cockroaches. Our findings deepen the understanding of the roles of E93 in controlling reproduction in insects, and of E93 expression and functional evolution, which are proposed to have made crucial contributions to the origin of insect metamorphosis. [ABSTRACT FROM AUTHOR]

Many insects are obligatorily associated with and dependent on specific microbial species as essential mutualistic partners. In the host insects, such microbial mutualists are usually maintained in specialized cells or organs, called bacteriocytes or symbiotic organs. Hence, potentially exponential microbial growth cannot be realized but must be strongly constrained by spatial and resource limitations within the host cells or tissues. How such endosymbiotic bacteria grow, divide, and proliferate is important for understanding the interactions and dynamics underpinning intimate host-microbe symbiotic associations. Here we report that Blattabacterium, the ancient and essential endosymbiont of cockroaches, exhibits unexpectedly high rates of cell division (20%-58%) and, in addition, the cell division is asymmetric (average asymmetry index >1.5) when isolated from the German cockroach Blattella germanica. The asymmetric division of endosymbiont cells at high frequencies was observed irrespective of host tissues (fat bodies vs ovaries) or developmental stages (adults vs nymphs vs embryos) of B. germanica, and also observed in several different cockroach species. By contrast, such asymmetric and frequent cell division was observed neither in Buchnera, the obligatory bacterial endosymbiont of aphids, nor in Pantoea, the obligatory bacterial gut symbiont of stinkbugs. Comparative genomics of cell division-related genes uncovered that the Blattabacterium genome lacks the Min system genes that determine the cell division plane, which may be relevant to asymmetric cell division. These observations combined with comparative symbiont genomics provide insight into what processes and regulations may underpin the growth, division, and proliferation of such bacterial mutualists continuously constrained under within-host conditions. IMPORTANCE Diverse insects are dependent on specific bacterial mutualists for their survival and reproduction. Due to the long-lasting coevolutionary history, such symbiotic bacteria tend to exhibit degenerative genomes and suffer uncultivability. Because of their microbiological fastidiousness, the cell division patterns of such uncultivable symbiotic bacteria have been poorly described. Here, using fine microscopic and quantitative morphometric approaches, we report that, although bacterial cell division usually proceeds through symmetric binary fission, Blattabacterium, the ancient and essential endosymbiont of cockroaches, exhibits frequent and asymmetric cell division. Such peculiar cell division patterns were not observed with other uncultivable essential symbiotic bacteria of aphids and stinkbugs. Gene repertoire analysis revealed that the molecular machinery for regulating the bacterial cell division plane are lost in the Blattabacterium genome, suggesting the possibility that the general trend toward the reductive genome evolution of symbiotic bacteria may underpin their bizarre cytological/morphological traits. [ABSTRACT FROM AUTHOR]

This study was performed to investigate the phylogenetic characters of the cockroaches in the Kayseri region for mitochondrial cytochrome c oxidase subunit I (mt-COI), mt-COII, and internal transcribed spacer-2 (ITS-2) gene regions. It was also aimed to determine their mechanical transmission of medically important parasites. PCR-restriction fragment length polymorphism (RFLP) was performed by using mt-COI, mt-COII, and ITS-2 DNA gene regions to identify cockroach species (n=220) collected from different regions. Differentiation of cockroach species was based on RFLP models using two restriction enzymes: AvaI and EciI. For phylogenetic analysis, mt-COI, mt-COII, and ITS-2 DNA barcode regions were amplified with standard primers. The obtained amplicons were purified and sequenced using the PCR primers. According to PCR-RFLP, the cockroach species were identified as Blattella germanica (n=105), Blatta orientalis (n=86), and Periplaneta americana (n=29). A total of 13 haplotypes were detected and maximum likelihood (ML) analyses revealed that the sequences of all three species showed a monophyletic structure for the three gene regions. The cockroaches were examined for the presence of parasites. It was found that of the 58 parasitic forms identified, 46 (79.3%) belonged to helminth species and 12 (20.7%) to protozoan species. The results showed that B. germanica (58.6%) had the highest prevalence, followed by Bl. orientalis (32.8%) and P. americana (8.6%). The results of the study not only contribute to the molecular epidemiology of cockroaches but also confirm their important role as mechanical vectors of protozoan and helminth parasites. [ABSTRACT FROM AUTHOR]

Background: German cockroaches are the most common cockroach species in the world. Although German cockroach infestations occur in many human-inhabited spaces, they are most commonly associated with restaurants, food processing facilities, hotels, nursing homes. It's also carried viruses, protozoa and infectious bacteria on the outside and inside of body surfaces and play a role in causing dizziness, asthma and nausea reactions in people. So, Blattella germanica is considered as an important medical and economic. Methods: This study aimed to evaluate the efficacy of Nerium oleander extract against cockroaches and inhibition hatching eggs in vitro using a dipping method test. Two graduated concentrations of extract (50 and 100 mg/ml) were tested at different periods and changes over time in the viability of cockroaches were registered for (1 and 2 hours) and in relation to Inhibition hatching eggs after 30 days. Distilled water and cypermethrin (0.1%) were used as negative and positive control, respectively. A chemical assay was performed by FT-IR to investigate the presence of several anticipated active chemical compounds in Nerium oleander leaf extract. Result: The analysis of phytochemicals by FT-IR for alcoholic extracts of Nerium oleander extracts revealed the presence of 12 effective chemical ingredients such as carbohydrates, alkaloids, flavonoids, glycosides and tannins. The results showed that the extract had high efficacy in killing Cockroaches that were exposed to a high concentration of extract (100 mg/mL), the mortality rate was (90 and 100%), compared to the (cypermethrin 0.1%), the mortality rate was (70 and 100%) during the periods (1 and 2 hr) respectively. While the eggs cockroaches that were exposed to concentration of extract (100 mg/mL) and positive control (cypermethrin 0.1%) the hatching rate was (60 and 60%) after 30 days period respectively. While the negative control (without treated) was the hatching eggs cockroaches rate is (100%) during that period. [ABSTRACT FROM AUTHOR]

The German cockroach, Blattella germanica (L.) (Blattodea: Ectobiidae), is a ubiquitous pest in affordable housing. They represent a major threat to human health due to their contribution of asthma-exacerbating allergens and the potential to transfer pathogenic microorganisms indoors. Despite well-documented pyrethroid resistance, pyrethroid-based broadcast residual insecticide products are often used by residents to control cockroaches in their homes. Additionally, there is little empirical independent testing of these products. Thus, it remains unclear how effective these commonly used do-it-yourself products are at controlling German cockroaches. This study represents a comprehensive examination of the efficacy of these products with direct, limited, and continuous exposure assays on a variety of common household surfaces on field populations of cockroaches with varying levels of pyrethroid resistance. While most products performed well when applied directly to test insects, mortality was substantially lower across all surfaces with limited exposure (30 min). In continuous exposure assays on a nonporous surface, products took at least 24 hr to cause 100% mortality in a field population, with some products taking up to 5 d to achieve 100% mortality. The findings of this study demonstrate a lack of residual efficacy from common pyrethroid-based consumer-use pesticides products. Given that it is not feasible to find and treat every cockroach in a home directly, the residuality of spray-based formulations is critical for products designed to control German cockroaches. Without residual efficacy, as shown in the consumer aerosol and spray products tested, we expect these products to add little to no value to cockroach control. [ABSTRACT FROM AUTHOR]

Background: The Endosomal Sorting Complex Required for Transport (ESCRT) is a highly conserved cellular machinery essential for many cellular functions, including transmembrane protein sorting, endosomal trafficking, and membrane scission. CHMP4B is a key component of ESCRT‐III subcomplex and has been thoroughly studied in the meroistic ovaries of Drosophila melanogaster showing its relevance in maintaining this reproductive organ during the life of the fly. However, the role of the CHMP4B in the most basal panoistic ovaries remains elusive. Results: Using RNAi, we examined the function of CHMP4B in the ovary of Blattella germanica in two different physiological stages: in last instar nymphs, with proliferative follicular cells, and in vitellogenic adults when follicular cells enter in polyploidy and endoreplication. In Chmp4b‐depleted specimens, the actin fibers change their distribution, appearing accumulated in the basal pole of the follicular cells, resulting in an excess of actin bundles that surround the basal ovarian follicle and modifying their shape. Depletion of Chmp4b also determines an actin accumulation in follicular cell membranes, resulting in different cell morphologies and sizes. In the end, these changes disrupt the opening of intercellular spaces between the follicular cells (patency) impeding the incorporation of yolk proteins to the growing oocyte and resulting in female sterility. In addition, the nuclei of follicular cells appeared unusually elongated, suggesting an incomplete karyokinesis. Conclusions: These results proved CHMP4B essential in preserving the proper expression of cytoskeleton proteins vital for basal ovarian follicle growth and maturation and for yolk protein incorporation. Moreover, the correct distribution of actin fibers in the basal ovarian follicle emerged as a critical factor for the successful completion of ovulation and oviposition. Significance: The overall results, obtained in two different proliferative stages, suggest that the requirement of CHMP4B in B. germanica follicular epithelium is not related to the proliferative stage of the tissue. [ABSTRACT FROM AUTHOR]

The German cockroach is a global urban pest that causes serious public health problems. The induced levels of insecticide tolerance in the first-generation strains of German cockroach from previous topical treatment of laboratory colonies with LD10 or LD25 doses of imidacloprid, indoxacarb, or lambda-cyhalothrin four times with seven-day interval between each were investigated. Our results showed that the resistant ratios (RR50) at LD50, cytochrome P450 content, and glutathione S-transferase (GSTs) activity in adult cockroaches increased in the first generation when compared to the parental (field) and susceptible strains (SS). Therefore, cockroaches treated with insecticidal sublethal dose are likely to have more insecticide resistance in comparison to untreated ones. [ABSTRACT FROM AUTHOR]

Finding substantial substitution of chemical pesticides to control cockroaches, which were proved to link with multiple health issues, has become the major target of many researchers. In fact, subjecting this pest to the effects of toxic plants extracts is considered ideal to primarily avoid jeopardizing human health. This study is divided into two objectives. The first is to confirm the toxicity of the ethanolic extract from the plant Cleome amblyocarpa Barratte & Murb, on two species of urban cockroaches; which are Blattella germanica (Linnaeus, 1767) and Shelfordella lateralis (Walker, 1868), while the second is to verify the effect of the attractive odor of the extract on the feeding behavior of the two already mentioned species. Therefore, the findings demonstrated that the extract causes a mortality rate of 60% of B. germanica after 30 days of treatment at a high concentration of (3g/l). The mortality rate in S. lateralis does not exceed 6.7%. Further, findings exhibited that the proportion of B. germanica attracted by the smell of the plant soaked in hexane at a specified time (15, 30 and 60 minutes) was estimated at 40%, whereas that of S. lateralis exceeded 60%. The results provide the presence of toxic elements within the examined extract, suggesting the potential for developing bio-insecticides derived from Cleome amblyocarpa for utilization in the pesticide industry. [ABSTRACT FROM AUTHOR]

Background: The German cockroach (Blattella germanica) is a pest with a global distribution that has adapted to live in human environments. Blattella germanica threatens human health by producing asthma-inducing allergens, carrying pathogenic/antibiotic-resistant microbes, and contributing to unhealthy indoor environments. Effective application of insecticides can play an important role in cockroach control programs. The purpose of this research was to develop and optimize a nanoparticle-based imidacloprid insecticide and evaluate its effectiveness against the German cockroach. Methods: A bioassay was conducted to determine the LC50 and LC90 of imidacloprid technical against adult German cockroaches. The appropriate initial concentration of 3mg/m2 was then utilized in the synthesis of nanoencapsulated imidacloprid via the ionic gelation method. The average particle size was determined using Dynamic Light Scattering (DLS) and the dried nanoparticles were analyzed using a Scanning Electron Microscope (SEM). The LC50 and LC90 values of Nano-imidacloprid were then compared with the technical grade of the insecticide. Results: A comparison of the bioassay results for nanoencapsulated and imidacloprid technical revealed a superior insecticidal effect of the nanoencapsulated imidacloprid against the German cockroach. The LC50 value for the nanoencapsulated imidacloprid decreased from 4.656 to 3.081 mg/m² and the LC90 value decreased from 8.381 to 4.486 mg/m² when compared to imidacloprid technical. Conclusion: The use of nanotechnology in insecticides can lead to increased efficacy and reduced consumption. This is because the smaller particle size of nanomaterials allows for better penetration and targeted delivery to pest organisms, reducing the overall amount needed for control. [ABSTRACT FROM AUTHOR]

Cockroaches, widespread pests found in metropolitan areas, are known as vectors of various disease agents, including viruses, fungi and antibiotic‐resistant bacteria, as well as causing allergies in humans. Insect growth regulators have been used in pest management for several decades. These insecticides disrupt insect development and reproduction. Chitin synthesis inhibitors interfere with chitin biosynthesis in insects, causing abortive moulting and mortality, as well as inhibiting egg fertility, and larval hatching in insects. In this research, we evaluated the various effects of diflubenzuron, a chitin synthesis inhibitor, on synthetic pyrethroid‐resistant German cockroach (Blattella germanica L. Blattodea: Ectobiidae), including ootheca production, oothecal viability, ootheca incubation time, the number of nymphs emerging from the ootheca and survivorship of nymphs. The cockroaches were fed diets that contained diflubenzuron, which was added to solid bait (impregnated fish food) and ingestible aqueous bait (impregnated cotton). Three concentrations (0.5%, 1% and 2%) were used in the experiments. As a result, diflubenzuron treatment led to ootheca production ranging from 60% to 100%; statistically, no difference was found between the treatment and the control groups. The number of nymphs emerging from the first and second ootheca was reduced by 40%–100% in the diflubenzuron‐treated groups compared with the control. Nymphs exposed to diflubenzuron‐impregnated solid bait and ingestible aqueous bait experienced mortality exceeding 92.1% and 66.27% within 15 days, respectively. In conclusion, diflubenzuron is a potential insecticide for use in cockroach baits to control B. germanica, as it caused high nymphal and embryonic mortality in the synthetic pyrethroid‐resistant population and decreased the number of nymphs emerging from the ootheca. [ABSTRACT FROM AUTHOR]

We investigated the expression of 4 cytochrome P450 genes (CYP4G19, CYP6J1, CYP6K1, and CYP4C21) in 4 field-collected strains (WM, RG386, CDR, and Ryan) of the German cockroach, Blattella germanica (L.), collected from California. The UCR susceptible strain was used as a comparison. Topical assays using a diagnostic dose (3× LD95) of deltamethrin revealed decreased sensitivity in all field-collected strains with mortality ranging from 0% to 58%, and the addition of PBO before deltamethrin treatment increased mortality to 52.5%–87.5%. Using qPCR to investigate the expression levels of CYP4G19, CYP4C21, CYP6J1, and CYP6K1, we found that only CYP6K1 was significantly overexpressed (2.1–5.8× higher) in all field-collected strains when compared to the UCR strain. Next, we investigated the role of the CYP6K1 gene by performing gene knockdown using RNAi. After dsCYP6K1 treatment, the expression levels of CYP6K1 in WM and Ryan strains were significantly reduced (P  < 0.01) by 91%–94% vs. those treated with dsEGFP (control) on the third and sixth day posttreatment. RG386, CDR, and Ryan strains were more susceptible compared to their respective controls to topically applied deltamethrin 6 days after treatment with dsCYP6K1. This study provides evidence of the involvement of the P450 CYP6K1 gene in pyrethroid resistance in some populations of German cockroaches. [ABSTRACT FROM AUTHOR]

The origin of the German cockroach, Blattella germanica, is enigmatic, in part because it is ubiquitous worldwide in human-built structures but absent from any natural habitats. The first historical records of this species are from ca. 250 years ago (ya) from central Europe (hence its name). However, recent research suggests that the center of diversity of the genus is Asian, where its closest relatives are found. To solve this paradox, we sampled genome-wide markers of 281 cockroaches from 17 countries across six continents. We confirm that B. germanica evolved from the Asian cockroach Blattella asahinai approximately 2,100 ya, probably by adapting to human settlements in India or Myanmar. Our genomic analyses reconstructed two primary global spread routes, one older, westward route to the Middle East coinciding with various Islamic dynasties (~1,200 ya), and another younger eastward route coinciding with the European colonial period (~390 ya). While Europe was not central to the early domestication and spread of the German cockroach, European advances in long-distance transportation and temperature-controlled housing were likely important for the more recent global spread, increasing chances of successful dispersal to and establishment in new regions. The global genetic structure of German cockroaches further supports our model, as it generally aligns with geopolitical boundaries, suggesting regional bridgehead populations established following the advent of international commerce. [ABSTRACT FROM AUTHOR]

Introduction: German cockroach (GCr) aeroallergens are associated with allergic rhinitis and asthma. Vitellogenin (Vg) and vitellin (Vn) are abundant proteins in GCr blood and eggs (including egg cases), respectively, and are possible high molecular mass allergens. Prior efforts to purify Vg/Vn yielded amounts too small for subsequent studies. In this study, we report the affinity purification of Vg/Vn from whole-body defatted GCr powder and determination of the binding of Vg/Vn to anti-GCr IgE. Method: New Zealand white rabbits were immunized with pure Vg/Vn in Freund's adjuvant, and IgG was purified from the rabbit sera and conjugated to cyanogen bromide (CNBr)-activated Sepharose. Aqueous extracts from GCr powder were passed over the column. After extensive washing, putative Vg/Vn was eluted in low-pH buffer, neutralized, and analyzed by SDS-PAGE and liquid chromatography high-resolution mass spectrometry (LC-HRMS). IgE binding of Vg/Vn was evaluated by inhibition of IgE binding to GCr-ImmunoCAP(I6) in sera from 10 GCr-allergic individuals. In addition, Vg/Vn was biotinylated and bound to ImmunoCAP-streptavidin, and direct IgE antibody binding to the immobilized Vg/Vn was determined in sera from 26 GCr-allergic individuals. Results: Vg/Vn isolated by affinity chromatography was 91% pure by LC-HRMS; contaminants included Bla g 3 (0.9%), human keratin (6%), and rabbit IgG. Vg/Vn inhibited IgE binding to GCr-ImmunoCAP(I6) in 8 of 10 sera. In direct-binding experiments, 21/26 (80%) sera had anti-Vg/Vn IgE at>0.10 kUA/L, while 11/26 (42%) sera were>0.35 kUA/L. Conclusions: We affinity-purified Vg/Vn and demonstrated that Vg/Vn-specific IgE antibody is a major component of GCr-specific IgE. [ABSTRACT FROM AUTHOR]

We explored the metabolic integration of Blattella germanica and its obligate endosymbiont Blattabacterium cuenoti by the transcriptomic analysis of the fat body of quasi-aposymbiotic cockroaches, where the endosymbionts were almost entirely removed with rifampicin. Fat bodies from quasi-aposymbiotic insects displayed large differences in gene expression compared to controls. In quasi-aposymbionts, the metabolism of phenylalanine and tyrosine involved in cuticle sclerotization and pigmentation increased drastically to compensate for the deficiency in the biosynthesis of these amino acids by the endosymbionts. On the other hand, the uricolytic pathway and the biosynthesis of uric acid were severely decreased, probably because the reduced population of endosymbionts was unable to metabolize urea to ammonia. Metabolite transporters that could be involved in the endosymbiosis process were identified. Immune system and antimicrobial peptide (AMP) gene expression was also reduced in quasi-aposymbionts, genes encoding peptidoglycan-recognition proteins, which may provide clues for the maintenance of the symbiotic relationship, as well as three AMP genes whose involvement in the symbiotic relationship will require additional analysis. Finally, a search for AMP-like factors that could be involved in controlling the endosymbiont identified two orphan genes encoding proteins smaller than 200 amino acids underexpressed in quasi-aposymbionts, suggesting a role in the host–endosymbiont relationship. [ABSTRACT FROM AUTHOR]

Genes involved in melanin production directly impact insect pigmentation and can affect diverse physiology and behaviours. The role these genes have on sex behaviour, however, is unclear. In the present study, the crucial melanin pigment gene black was functionally characterised in an urban pest, the German cockroach, Blattella germanica. RNAi knockdown of B. germanica black (Bgblack) had no effect on survival, but did result in black pigmentation of the thoraxes, abdomens, heads, wings, legs, antennae, and cerci due to cuticular accumulation of melanin. Sex-specific variation in the pigmentation pattern was apparent, with females exhibiting darker coloration on the abdomen and thorax than males. Bgblack knockdown also resulted in wing deformation and negatively impacted the contact sex pheromone-based courtship behaviour of males. This study provides evidence for black function in multiple aspects of B. germanica biology and opens new avenues of exploration for novel pest control strategies. [ABSTRACT FROM AUTHOR]

Urban pests such as cockroaches prefer urban environments within and around the home to establish their colonies. These insects may potentially be more attracted to unconventional construction materials, which would mean a deterioration not only of the materials but also of urban environments. The objective of this study was to assess the degree of attraction of the "cockroach" Blattella germanica (L.) towards three non-conventional construction materials (Polyethylene Terephthalate - PET-, African Palm Kernel Ash - PKSA- and Polyethylene-Aluminum-Polyethylene pipe - PealPe) in tropical climates. An experimental study was carried out evaluating the attraction to B. germanica using an olfactometer. There was no preference of adult males and females of B. germanica towards unconventional concrete (p> 0,005). The selection time distribution was the same for the three concretes analyzed. There was no attraction of B. germanica towards non-conventional concretes made with PET, PeAlPe and PKSA; but a slight trend of choice towards concrete made with PKSA is evident. The use of non -conventional concrete can be an alternative for construction, both for complying with construction regulations and for not resulting more attractive to cockroaches than conventional materials such as concrete. [ABSTRACT FROM AUTHOR]

Lipid and sugar homeostasis is critical for insect development and survival. In this study, we characterized an acetyl coenzyme A carboxylase gene in Blattella germanica (BgACC) that is involved in both lipogenesis and sugar homeostasis. We found that BgACC was dominantly expressed in the fat body and integument, and was significantly upregulated after molting. Knockdown of BgACC in 5th‐instar nymphs did not affect their normal molting to the next nymphal stage, but it caused a lethal phenotype during adult emergence. BgACC‐RNA interference (RNAi) significantly downregulated total free fatty acid (FFA) and triacylglycerol (TAG) levels, and also caused a significant decrease of cuticular hydrocarbons (CHCs). Repression of BgACC in adult females affected the development of oocytes and resulted in sterile females, but BgACC‐RNAi did not affect the reproductive ability of males. Interestingly, knockdown of BgACC also changed the expression of insulin‐like peptide genes (BgILPs), which mimicked a physiological state of high sugar uptake. In addition, BgACC was upregulated when B. germanica were fed on a high sucrose diet, and repression of BgACC upregulated the expression of the glycogen synthase gene (BgGlyS). Moreover, BgACC‐RNAi increased the circulating sugar levels and glycogen storage, and a longevity assay suggested that BgACC was important for the survival of B. germanica under conditions of high sucrose uptake. Our results confirm that BgACC is involved in multiple lipid biogenesis and sugar homeostasis processes, which further modulates insect reproduction and sugar tolerance. This study benefits our understanding of the crosstalk between lipid and sugar metabolism. [ABSTRACT FROM AUTHOR]

Chitin synthase is an indispensable enzyme that is involved in the synthesis of chitin, a key component of the insect cuticle during insect development, which has long been considered a potential target for pest control. The German cockroach Blattella germanica is a notorious urban pest that has developed resistance to more than one class of insecticide. Therefore, there is an urgent need to explore novel green molecular approaches for sustainable insect pest control. In this study, two chitin synthase (CHS) genes (BgCHS1 and BgCHS2) were identified for the first time in B. germanica: Phylogenetic relationships, motif patterns, and conserved domain regions of all the predicted CHS genes were identified. Furthermore, the function characteristic of the two BgCHS genes was studied using a microinjection-based RNAi system. The results showed that silencing of BgCHS1 and BgCHS2 both resulted in high mortality. Knockdown of the BgCHS1 gene resulted in impaired molting and abnormal development, while knockdown of the BgCHS2 gene expression resulted in abnormal development. Additionally, a large-scale dsRNA production system via Escherichia coli was built and a nanoparticle-based (Star Polymers, SPc) oral delivery system of an SPc-wrapped two dsRNA of dsBgCHS1 and dsBgCHS2 was evaluated, which resulted in a high mortality and ultrastructural changes in the integument and midgut of cockroach nymphs, respectively. This study illustrates the functions of the two novel identified CHS genes in B. germanica, which can serve as potential gene targets for controlling one of the most serious urban health pests. [ABSTRACT FROM AUTHOR]

The brown-banded cockroach (Supella longipalpa) is a widespread nuisance and public health pest. Like the German cockroach (Blattella germanica), this species is adapted to the indoor biome and completes the entirety of its life cycle in human-built structures. Recently, understanding the contributions of commensal and symbiotic microbes to the biology of cockroach pests, as well as the applications of targeting these microbes for pest control, have garnered significant scientific interest. However, relative to B. germanica, the biology of S. longipalpa, including its microbial associations, is understudied. Therefore, the goal of the present study was to quantitatively examine and characterize both the endosymbiont and gut bacterial communities of S. longipalpa for the first time. To do so, bacterial 16S rRNA gene amplicon sequencing was conducted on DNA extracts from whole adult females and males, early instar nymphs, and late instar nymphs. The results demonstrate that the gut microbiome is dominated by two genera of bacteria known to have beneficial probiotic effects in other organisms, namely Lactobacillus and Akkermansia. Furthermore, our data show a significant effect of nymphal development on diversity and variation in the gut microbiome. Lastly, we reveal significant negative correlations between the two intracellular endosymbionts, Blattabacterium and Wolbachia, as well as between Blattabacterium and the gut microbiome, suggesting that Blattabacterium endosymbionts could directly or indirectly influence the composition of other bacterial populations. These findings have implications for understanding the adaptation of S. longipalpa to the indoor biome, its divergence from other indoor cockroach pest species such as B. germanica, the development of novel control approaches that target the microbiome, and fundamental insect-microbe interactions more broadly. [ABSTRACT FROM AUTHOR]

Artificial or non-nutritive sweeteners are indigestible by most animals. Some sweeteners are orally toxic to insects and have received recent interest as potential safe insecticides due to their low mammalian toxicity. In this study, we investigated the oral toxicity of sucralose on insecticide-susceptible and resistant German cockroaches, Blattella germanica (L.). In a nonchoice test, we evaluated 5, 10, and 20% sucralose solutions. Depending on the cockroach strains, mean mortality ranged from 62.5 to 92.5%, 15 to 55%, and 2.5 to 27.5% for 20, 10, and 5% sucralose, respectively. Next, we measured the impact of a 20% sucralose treatment on water loss rates in the cockroach strains. All strains lost 23.0–30.29% of body water by 6 d. Dehydrated cockroaches were more prone to be killed by sucralose than nondehydrated ones. Lastly, we evaluated the effect of 20% sucralose treatment on gut bacterial composition and found the diversity of gut bacteria in treated cockroaches was significantly reduced after 3 days, implicating a rapid change in the alimentary environment. [ABSTRACT FROM AUTHOR]

BACKGROUND: Pyrethroids are synthetic insecticides with low mammalian toxicity and broad‐spectrum activity across insects. One major challenge with pyrethroids is their perceived repellency. This perception can influence decisions made by pest control operators, especially when insecticides are used to reduce insect entry into or movement within structures. One major indoor pest that has been repeatedly shown to be repelled by some pyrethroids is the German cockroach, Blattella germanica. However, most experiments evaluating pyrethroid repellency in the German cockroach have used end‐point assays, which do not provide information on the movement that led to the final position. Therefore, we evaluated the kinetic behavioral response of field‐collected German cockroaches to five pyrethroid‐based products and their active ingredients (A.I.) in open behavioral arenas using advanced video tracking software. In addition, in an effort to compare our free‐moving experiments with end‐point assays, we evaluated sheltering behavior using two‐choice harborage arrestment assays where German cockroaches were provided a choice between pyrethroid‐treated and untreated shelters. RESULTS: All pyrethroid‐formulated products and their respective A.I.'s failed to affect field‐collected German cockroach movement behavior in free‐moving assays, while positive controls (DEET, corn mint oil) resulted in reduced time spent by German cockroaches in treated areas. However, despite their willingness to move over pyrethroids‐treated surfaces, field‐collected German cockroaches displayed a reduced propensity to arrest on pyrethroids treated tents. CONCLUSION: While most pyrethroids/pyrethroid‐formulated products affected German cockroach arrestment, pyrethroids and pyrethroid‐formulated products failed to change German cockroach movement behavior in free‐moving assays. These results indicate the pyrethroids tested act as contact irritants rather than true‐spatial repellents on field‐collected German cockroaches. This distinction is critical to refining pest management strategies involving pyrethroids. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Cockroaches harbor two coexisting symbiotic systems: the obligate endosymbiont Blattabacterium cuenotii, and a complex gut microbiota. Blattabacterium is the only bacterium present in the eggs, as the gut microbiota is acquired by horizontal transmission after hatching, mostly through coprophagy. Blattella germanica, a cosmopolitan omnivorous cockroach living in intimate association with humans, is an appropriate model system for studying whether the gut microbiota is essential for the cockroach's survival, development, or welfare. We obtained a germ-free cockroach population (i.e., containing normal amounts of the endosymbiont, but free of microbes on the insects' surface and digestive tract). Non-significant differences with the controls were detected in most fitness parameters analyzed, except for a slight shortening in the hatching time of the second generation and a reduction in female weight at 10 days after adult ecdysis. The latter is accompanied by a decrease in uric acid reserves. This starvation-like phenotype of germ-free B. germanica suggests that the microbiota is not essential in this species for survival and development throughout its complete life cycle, but it could participate in complementation of host nutrition by helping with food digestion and nutrient absorption. [ABSTRACT FROM AUTHOR]

DNA methylation at the fifth position of cytosine (5-methylcytosine, 5mC) is a crucial epigenetic modification for regulating gene expression, but little is known about how it regulates gene expression in insects. Here, we pursue the detailed molecular mechanism by which DNMT1-mediated 5mC maintenance regulates female reproduction in the German cockroach, Blattella germanica. Our results show that Dnmt1 knockdown decreases the level of 5mC in the ovary, upregulating numerous genes during choriogenesis, especially the transcription factor ftz-f1. The hypomethylation at the ftz-f1 promoter region increases and prolongs ftz-f1 expression in ovarian follicle cells during choriogenesis, which consequently causes aberrantly high levels of 20-hydroxyecdysone and excessively upregulates the extracellular matrix remodeling gene Mmp1. These changes further impair choriogenesis and disrupt fertilization by causing anoikis of the follicle cells, a shortage of chorion proteins, and malformation of the sponge-like bodies. This study significantly advances our understanding of how DNA 5mC modification regulates female reproduction in insects. The mechanism by which DNA methylation regulates female reproduction in insects is largely unknown. Here Zhao et al. demonstrate that the 5mC modification orchestrates timely choriogenesis and proper fertilization by preventing prolonged ftz-f1 expression in the German cockroach. [ABSTRACT FROM AUTHOR]

Background: Taiwan's warm and humid climate and dense population provide a suitable environment for the breeding of pests. The three major urban insects in Taiwan are house flies, cockroaches, and mosquitoes. In cases where a disease outbreak or high pest density necessitates chemical control, selecting the most effective insecticide is crucial. The resistance of pests to the selected environmental insecticide must be rapidly assessed to achieve effective chemical control and reduce environmental pollution. Methods: In this study, we evaluated the resistance of various pests, namely, house flies (Musca domestica L.), cockroaches (Blattella germanica L. and Periplaneta americana), and mosquitoes (Aedes aegypti and Ae. albopictus) against 10 commonly used insecticides. Rapid insecticide resistance bioassays were performed using discriminating doses or concentrations of the active ingredients of insecticides. Results: Five field strains of M. domestica (L.) are resistant to all 10 commonly used insecticides and exhibit cross- and multiple resistance to four types of pyrethroids and three types of organophosphates, propoxur, fipronil, and imidacloprid. None of the five field strains of P. americana are resistant to any of the tested insecticides, and only one strain of B. germanica (L.) is resistant to permethrin. One strain of Ae. albopictus is resistant to pirimiphos-methyl, whereas five strains of Ae. aegypti exhibit multiple resistance to pyrethroids, organophosphates, and other insecticides. Conclusions: In the event of a disease outbreak or high pest density, rapid insecticide resistance bioassays may be performed using discriminating doses or concentrations to achieve precise and effective chemical control, reduce environmental pollution, and increase control efficacy. [ABSTRACT FROM AUTHOR]

The transcription factor Ftz‐f1 has multiple functions in insect development in a spatial‐temporal line. One of these roles is in the insect ovaries, specifically in the regulation of steroidogenic enzymes production. We studied the function of F in Blattella germanica oogenesis, as it shows two moments of high expression in ovaries: before the imaginal moult, and just before ovulation in the adult. Injecting dsftz‐f1 into adult females, either just after the imaginal moult or just prior to choriogenesis, prevented oviposition, with differences between the two approaches. In 3‐day‐old adult females treated with dsftz‐f1 just after the emergence, the expression of ftz‐f1 was not modified, but the steroidogenic genes increased their expression. ftz‐f1 transcript levels in the ovaries of 5‐day‐old dsftz‐f1‐treated females were significantly depleted, and the expression levels of the same steroidogenic genes began to decrease. These results suggest that Ftz‐f1 regulates the expression of steroidogenic genes in B. germanica, with phm possibly being a key target. Ftz‐f1 has a different temporal function in the cytoskeleton of follicular cells of the basal ovarian follicles. Early in the gonadotrophic cycle, Ftz‐f1 promotes the expression of genes related to the cytoskeleton and muscle proteins, while at the end of the cycle it maintains the expression levels of these genes, thus ensuring correct ovulation. [ABSTRACT FROM AUTHOR]

This study aims to reduce the cost of allergen testing for Guangzhou, China by limiting the number of allergens for which patients are tested, and provide a testing panel to improve diagnostic and therapeutic efficiency. This retrospective study of real-world data from 2012 to 2019 included 39,570 patients with suspected allergies in Guangzhou, southern China. All the patients were tested for one or more of the following allergens serum specific immunoglobulin E (sIgE): Dermatophagoides pteronyssinus, Dermatophagoides farinae, cat dander, dog dander, Artemisia vulgaris, Aspergillus fumigatus, Alternaria alternata, Blattella germanica, egg whites, milk, wheat, peanuts, soybeans, Cancer pagurus, and Penaeus monodon by PhadiaCAP 1000. Totally, only the positive rates of allergens sIgE in D. farinae, D. pteronyssinus, milk, egg whites, B. germanica, C. pagurus, A. alternata, and P. monodon were > 10%, the other allergens were between 4–7%. Moreover, among the allergic diseases, dust mites exhibited the overall highest positive rate, followed by milk and B. germanica. In children, milk was the main allergen, whereas in adults, mites, cockroaches, shrimp, and crab allergens had higher positive rates. The optimal scale analysis shows that the multiple sensitization classification of patients can be divided into three categories: I D. farinae and D. pteronyssinus; II. C. pagurus, P. monodon, and B. germanica; III. Milk and egg whites. Generally, a panel including 4 allergens can detect > 90% of the potential allergy in this local population. In Guangzhou, southern China, D. farinae, milk, B. germanica, and A. alternata as a panel screening allergy for suspected allergic patients was suggested base on this study. [ABSTRACT FROM AUTHOR]

Numerous studies have focussed on the mechanisms of entry of pesticides into insect body parts such as oral intake, penetration through the integument of the body wall, and inhalation through spiracles. However, little is known about how insecticides spread to the points of entry or the paths on the body surface that are used to reach the target sites. In this study, elemental signals of pesticide-mimicking test solutions were tracked and their routes of spreading in experimental insects (Blattella germanica L.) were investigated using NanoSuit (a method of surface modification) and energy dispersive X-ray spectroscopy, combined with high-resolution scanning electron microscopy. When the test solution initially adhered to the dorsal and/or ventral body surface, it tended to spread horizontally to reach lateral plates. Whereas, when the solution directly adhered to the anterior side of the lateral plates, it spread to posterior segments. In this case, however, spreading in the opposite direction (i.e., the solution directly adhered to the posterior side of the lateral plates) was interrupted at a boundary erected by different groups of fine structures; each protrusion was large, and the arrangement was rather dense in the posterior segments. Morphological features of these fine structures and chemical characteristics of the hydrophobic surface substances potentially regulate the strength of the capillary force, which determines pesticide spreading. [ABSTRACT FROM AUTHOR]

Aim: It is aimed to contribute to preventive measures by determining the distribution of allergens in patients with allergic rhinitis and asthma in Kırıkkale and to contribute to the creation of the allergy map of our country. Materials and Methods: The files of patients who underwent skin prick test at Kırıkkale Yüksek İhtisas Hospital between 2018 and 2022 were retrospectively analyzed. Results: A total of 6,056 people, 4,464 (73.7%) women and 1,592 (26.3%) men, were applied skin prick test within 5 years. Of the test results, 3,454 (57%) were positive and 2,602 (43%) were negative. While 622 (10.3%) of 3,454 positive patients were sensitive to a single allergen, 2,832 (46.8%) were sensitive to multiple allergens. The most common positivity rate in the skin prick test is Blattella germanica (cockroach) (24.2%), Dermatophagoides (D.) Farinae (house dust mite) (21.9%), herb mixture (plant grass, wormwood, buckwheat, sticky grass) (weed pollen) (19%) and D. Pteronyssinus (house dust mite) (18.4%) was found. When the pollens were examined collectively rather than individually (test 5 willow pollen 10.7%, test 6 cereal pollen 17.8%, test 7 poplar pollen 14.0%), it was determined as 42.5%. House dust mites D. Farinae and D. Pteronyssinus together were determined to be 40.3% allergen positive. Conclusion: It was determined that the most common allergens in Kırıkkale province were cockroaches, pollen and house dust mites. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to compare the resistance rates of Blattella germanica to beta-cypermethrin nanoemulsion and conventional emulsion and establish reference values via biochemical detection for conventional emulsion. Methods: We conducted experiments using subcultured Blattella germanica and applied the micro-drop method for treatment. Subsequently, the activity of metabolic enzymes was measured using spectrophotometry. Profile analysis was employed to study the resistance rates of beta-cypermethrin nanoemulsion and beta-cypermethrin emulsion. Results: The regression equation for the relationship between generation and resistance factor in Blattella germanica treated with beta-cypermethrin nanoemulsion was as follows: y1 = 0.091x1 + 0.991, with an r-value of 0.990 (F = 95.184, p = 0.01 < 0.05). Similarly, the regression equation for Blattella germanica treated with emulsion was y2 = 0.376x2 + 1.051, with an r-value of 0.993 (F = 141.094, p = 0.007 < 0.05). The comparison of slopes between these two regression equations yielded an F-value of 8.61, indicating a significant difference (p = 0.001 < 0.05). Conclusion: Our findings suggest that the resistance factor in Blattella germanica treated with beta-cypermethrin nanoemulsion differs from that treated with beta-cypermethrin emulsion. Specifically, the resistance factor of beta-cypermethrin nanoemulsion increased at a slower rate compared to beta-cypermethrin emulsion. [ABSTRACT FROM AUTHOR]

The Asian cockroach, Blattella asahinai Mizukubo, is a peridomestic nuisance pest in the southeastern United States. Blattella asahinai is the closest relative to Blattella germanica (L.), the German cockroach, one of the most prolific and widespread domestic pests. Because these two species live in different habitats, they are expected to have differential development patterns reflecting environmental adaptations. Development of B. asahinai and B. germanica cockroach nymphs were observed at six constant temperatures ranging from 10 to 35 °C. At 10 °C and 15 °C, all nymphs died in the first instar, but B. germanica nymphs survived longer (10 °C: 12.9 d; 15 °C: 42.9 d) than B. asahinai nymphs (10 °C 8.2 d; 15 °C 18.4 d) at both temperatures. At 20 °C, 25 °C, and 30 °C, B. asahinai consistently had more instars and longer stadia than B. germanica. At 35 °C, only B. germanica was able to complete nymphal development; cannibalism among B. asahinai nymphs during molting was often observed at this temperature. The results for B. asahinai corroborated previously estimated growth patterns. The lower nymphal development threshold was 14.1 °C for B. germanica and 13.7 °C for B. asahinai. Comparing the development of B. germanica directly with its closest relative reveals specific physiological adaptations that B. germanica has developed for the indoor biome. [ABSTRACT FROM AUTHOR]

TAIMAN (TAI), the only insect ortholog of mammalian Steroid Receptor Coactivators (SRCs), is a critical modulator of ecdysone and juvenile hormone (JH) signaling pathways, which govern insect development and reproduction. The modulatory effect is mediated by JH-dependent TAI's heterodimerization with JH receptor Methoprene-tolerant and association with the Ecdysone Receptor complex. Insect hormones regulate insect physiology and development in concert with abiotic cues, such as photo- and thermoperiod. Here we tested the effects of JH and ecdysone signaling on the circadian clock by a combination of microsurgical operations, application of hormones and hormone mimics, and gene knockdowns in the linden bug Pyrrhocoris apterus males. Silencing taiman by each of three non-overlapping double-strand RNA fragments dramatically slowed the free-running period (FRP) to 27–29 hours, contrasting to 24 hours in controls. To further corroborate TAIMAN's clock modulatory function in the insect circadian clock, we performed taiman knockdown in the cockroach Blattella germanica. Although Blattella and Pyrrhocoris lineages separated ~380 mya, B. germanica taiman silencing slowed the FRP by more than 2 hours, suggesting a conserved TAI clock function in (at least) some insect groups. Interestingly, the pace of the linden bug circadian clock was neither changed by blocking JH and ecdysone synthesis, by application of the hormones or their mimics nor by the knockdown of corresponding hormone receptors. Our results promote TAI as a new circadian clock modulator, a role described for the first time in insects. We speculate that TAI participation in the clock is congruent with the mammalian SRC-2 role in orchestrating metabolism and circadian rhythms, and that TAI/SRCs might be conserved components of the circadian clock in animals. Author summary: Most living creatures need to synchronize their rhythmic biological functions with the 24-hour day/night cycle of Earth. Instead of pocket watches or cell phones, they use intracellular molecular clocks to anticipate the daily recurring changes. Those circadian clocks are at the genetic level remarkably conserved among mammals and insects. Here, for the first time in insects, we introduce the protein TAIMAN as a new modulator of the circadian clock. The removal of TAIMAN from the adult linden bug Pyrrhocoris apterus or the German cockroach Blattella germanica males slows the clock by 2–4 hours. Circadian clocks often adjust animals' physiology through various hormones and neuropeptides. Insect endocrinology is dominated by the steroid and steroid-like hormones, ecdysone, and juvenile hormone: and TAIMAN is closely engaged in both juvenile hormone and ecdysone receptor signaling. However, the circadian role of TAIMAN presented here modulates the clock in a hormone-independent way. Importantly, TAIMAN is related to the mammalian SRC-2 protein, which is involved in regulating circadian clock machinery in mice. Thus, the novel role we describe for TAIMAN in insects may have a counterpart in mammalian physiology. [ABSTRACT FROM AUTHOR]

We investigated insecticide resistance profiles of field populations of the German cockroach, Blattella germanica (L.), collected from central regions of Thailand. Seven strains (PW, RB, MTH, MTS, TL, AY, and SP) were evaluated with diagnostic doses (DD; 3 × LD95 generated from a susceptible strain) of deltamethrin, fipronil, and imidacloprid using topical assays and compared with a susceptible strain (DMSC). Results showed fipronil (2–27% mortality), deltamethrin (16–58% mortality), and imidacloprid (15–75% mortality) resistance in the field strains. Synergism studies with piperonyl butoxide (PBO) and S,S,S-tributyl phosphorotrithioate (DEF) in combination with the DD of insecticides significantly increased (P < 0.05) mortality of the test insects of the field strains suggesting the involvement of P450 monooxygenase and esterase pathways of detoxification. Gel bait evaluations demonstrated that all field-collected strains were resistant to Maxforce Forte (0.05% fipronil), Maxforce Fusion (2.15% imidacloprid), and Advion Cockroach Gel Bait (0.6% indoxacarb) with mean survival times ranging from 1.87–8.27, 1.77–11.72, and 1.19–3.56 days, respectively. Molecular detection revealed that the Rdl mutation was completely homozygous in all field-collected strains except in the PW strain. Field-collected strains were screened for 3 voltage-gated sodium channel (VGSC) mutations associated with pyrethroid resistance. The L993F mutation was present in 5 strains, but no C764R and E434K mutations were detected. [ABSTRACT FROM AUTHOR]

BACKGROUND: The German cockroach, Blattella germanica, is a ubiquitous and medically significant urban pest. The ongoing development of insecticide resistance in global populations of B. germanica has complicated control efforts and created a need for improved tools. We previously reported that disruption of the gut microbiota by oral administration of the antimicrobial doxycycline reduced resistance in an indoxacarb resistant field strain and also delayed nymphal development and reduced adult fecundity. However, the application of doxycycline for cockroach control in the field is impractical. Here, we sought to determine whether two metal nanoparticles with known antimicrobial properties, copper (Cu) and zinc oxide (ZnO), have similar effects to doxycycline on the physiology of B. germanica and could provide more practical alternatives for control. RESULTS: We found that dietary exposure to 0.1% Cu nanoparticles, but not ZnO, significantly delays the development of nymphs into adults. However, neither of the nanoparticles altered the fecundity of females, and ZnO surprisingly increased resistance to indoxacarb in a resistant field strain, in contrast to doxycycline. Semi‐quantitative polymerase chain reaction (qPCR) further revealed that prolonged dietary exposure (14 days) to Cu or ZnO nanoparticles at the low concentration readily consumed by cockroaches (0.1%) does not reduce the load of the bacterial microbiota, suggesting alternative mechanisms behind their observed effects. CONCLUSIONS: Together, our results indicate that ingestion of Cu nanoparticles can impact German cockroach development through an undetermined mechanism that does not involve reducing the overall load of the bacterial microbiota. Therefore, Cu may have some applications in cockroach control as a result of this activity but antagonistic effects on insecticide resistance should be considered when evaluating the potential of nanoparticles for cockroach control. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]