Protease-Activated Receptors 2-Antagonist Suppresses Asthma by Inhibiting Reactive Oxygen Species-Thymic Stromal Lymphopoietin Inflammation and Epithelial Tight Junction Degradation

PURPOSE: Protease-activated receptor 2 (PAR2) reportedly triggers the immune response in allergic asthma. We aimed to investigate the mechanism on allergic inflammation mediated by PAR2. METHODS: Human lung epithelial cells (A549 cells) were used for in vitro, and the German cockroach extract (GCE)-induced mouse model was developed for in vivo studies. RESULTS: In A549 cells, the levels of reactive oxygen species (ROS) and thymic stromal lymphopoietin (TSLP) were significantly increased by GCE treatment, but were suppressed by PAR2-antagonist (PAR2-ant) or N-acetylcysteine (NAC) treatment. Claudin-1 was degraded by GCE, and was restored by PAR2-ant or NAC in the cells. In the mouse model, the clinical appearance including bronchial hyperresponsiveness, bronchoalveolar lavage fluid analysis and total immunoglobulin E were significantly suppressed by PAR2-ant or NAC. Moreover, TSLP levels in the lung were suppressed by the same treatments in the lung. Claudin-1 was also degraded by GCE, and was restored by PAR2-ant or NAC. CONCLUSIONS: ROS generation and epidermal tight junction degradation are triggered by protease, followed by the induction of TSLP in allergic asthma. Our findings could suggest that PAR2-ant or anti-oxidants could be considered for allergic diseases as preventive alternatives.

German Cockroach Extract Induces Matrix Metalloproteinase-1 Expression, Leading to Tight Junction Disruption in Human Airway Epithelial Cells

PURPOSE: Cockroach exposure is a pivotal cause of asthma. Tight junctions are intercellular structures required for maintenance of the barrier function of the airway epithelium, which is impaired in this disease. Matrix metalloproteinases (MMPs) digest extracellular matrix components and are involved in asthma pathogenesis: MMP1 is a collagenase with a direct influence on airway obstruction in asthmatics. This study aimed to investigate the mechanism by which German cockroach extract (GCE) induces MMP1 expression and whether MMP1 release alters cellular tight junctions in human airway epithelial cells (NCI-H292). MATERIALS AND METHODS: mRNA and protein levels were determined using real-time PCR and ELISA. Tight junction proteins were detected using immunofluorescence staining. Epithelial barrier function was measured by transepithelial electrical resistance (TEER). The binding of a transcription factor to DNA molecules was determined by electrophoretic mobility shift assay, while the levels of tight junction proteins and phosphorylation were determined using Western blotting. RESULTS: GCE was shown to increase MMP1 expression, TEER, and tight junction degradation. Both an inhibitor and small interfering RNA (siRNA) of MMP1 significantly decreased GCE-induced tight junction disruption. Furthermore, transient transfection with ETS1 and SP1 siRNA, and anti-TLR2 antibody pretreatment prevented MMP1 expression and tight junction degradation. An extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase (MAPK) inhibitor also blocked MMP1 release, ETS1/SP1 DNA binding, and tight junction alteration. CONCLUSION: GCE treatment increases MMP1 expression, leading to tight junction disruption, which is transcriptionally regulated and influenced by the ERK/MAPK pathway in airway epithelial cells. These findings may contribute to developing novel therapeutic strategies for airway diseases.

dNP2-ctCTLA-4 inhibits German cockroach extract-induced allergic airway inflammation and hyper-responsiveness via inhibition of Th2 responses

German cockroaches are major household allergens that can trigger allergic airway inflammatory diseases with sensitive T-cell responses. Although the use of immune modulatory biologics, such as antibodies, to mediate allergic responses has recently been examined, only systemic administration is available because of the size limitations on intranasal administration. Here we utilized a cell-permeable peptide, dNP2, to deliver the cytoplasmic domain of cytotoxic T-lymphocyte antigen-4 (ctCTLA-4) through the airway epithelium to modulate Th2 responses in a German cockroach extract (GCE)-induced allergic airway inflammation model. The intranasal delivery efficiency of the dNP2-dTomato protein to the lungs was higher in GCE-induced asthmatic lung parenchymal cells compared to the sham cells. Intranasal administration of the dNP2-ctCTLA-4 protein inhibited airway hyper-responsiveness and reduced airway inflammation and remodeling, including goblet cell metaplasia and collagen deposition around the bronchi. The number of infiltrated cells, including eosinophils, and the levels of IL-4, IL-5, IL-13 and IFN-γ in the lungs were significantly reduced, presumably owing to inhibition of Th2 differentiation. However, intranasal administration of CTLA4-Ig did not inhibit airway inflammation. These results collectively suggest that dNP2-ctCTLA-4 is an efficient intranasally applicable candidate biologic for treating allergic asthma.

Allergenic Characterization of a Novel Allergen, Homologous to Chymotrypsin, from German Cockroach

PURPOSE: Cockroach feces are known to be rich in IgE-reactive components. Various protease allergens were identified by proteomic analysis of German cockroach fecal extract in a previous study. In this study, we characterized a novel allergen, a chymotrypsin-like serine protease. METHODS: A cDNA sequence homologous to chymotrypsin was obtained by analysis of German cockroach expressed sequence tag (EST) clones. The recombinant chymotrypsins from the German cockroach and house dust mite (Der f 6) were expressed in Escherichia coli using the pEXP5NT/TOPO vector system, and their allergenicity was investigated by ELISA. RESULTS: The deduced amino acid sequence of German cockroach chymotrypsin showed 32.7 to 43.1% identity with mite group 3 (trypsin) and group 6 (chymotrypsin) allergens. Sera from 8 of 28 German cockroach allergy subjects (28.6%) showed IgE binding to the recombinant protein. IgE binding to the recombinant cockroach chymotrypsin was inhibited by house dust mite chymotrypsin Der f 6, while it minimally inhibited the German cockroach whole body extract. CONCLUSIONS: A novel allergen homologous to chymotrypsin was identified from the German cockroach and was cross-reactive with Der f 6.

External Bacterial Flora and Antimicrobial Susceptibility Patterns of Staphylococcus spp. and Pseudomonas spp. Isolated from Two Household Cockroaches, Blattella germanica and Blatta orientalis / 生物医学与环境科学（英文）

A study was performed to estimate the prevalence of the external bacterial flora of two domestic cockroaches (Blattella germanica and Blatta orientalis) collected from households in Tebessa (northeast Algeria). Three major bacterial groups were cultured (total aerobic, enterobacteria, and staphylococci) from 14 specimens of cockroaches, and antibiotic susceptibility was tested for both Staphylococcus and Pseudomonas isolates. Culturing showed that the total bacterial load of cockroaches from different households were comparable (P<0.001) and enterobacteria were the predominant colonizers of the insect surface, with a bacterial load of (2.1 × 10⁵ CFU/insect), whereas the staphylococci group was the minority. Twenty-eight bacterial species were isolated, and susceptibility patterns showed that most of the staphylococci isolates were highly susceptible to chloramphenicol, gentamycin, pristinamycin, ofloxacin, clindamycin, and vancomycin; however, Pseudomonas strains exhibited resistance to amoxicillin/clavulanic acid, imipenem, and the second-generation antibiotic cephalosporin cefuroxime.

Sensitization patterns to common allergens in Korean children younger than 6 years of age presenting with typical symptoms or signs of allergic diseases: a single center study

PURPOSE: Population studies have reported that sensitization to inhalant allergens is rare in young children; however, most subjects in those studies had little or no symptoms or signs highly suggestive of allergic diseases. The aim of the present study was to assess the prevalence of sensitization to inhalant allergens in young children with symptoms and/or signs of allergic disease. METHODS: We analyzed the results of all specific IgE tests performed at our hospital laboratory in children younger than 6 years presenting with symptoms and/or signs highly suggestive of allergic diseases between 2008 and 2013. Specific IgE tests for Dermatophagoides pteronyssinus, Dermatophagoides farinae, Alternaria alternata, German cockroach, cat dander, egg white or egg yolk, milk, peanut, and soybean were performed on 295 children; a specific IgE concentration > or =0.35 or > or =0.2 IU/mL was considered positive. We also compared allergen sensitization rates using the two cutoff values. RESULTS: One hundred eighty-one children (61.4%) were positive to at least 1 allergen tested and 53 children (18.9%) were positive to at least 1 inhalant allergen when a specific IgE concentration > or =0.35 IU/mL was considered positive. The children were more likely to have asthma or allergic rhinitis when they were sensitized to any inhalant allergen, particularly house dust mites. The prevalence of sensitization to inhalant allergens increased with age (P<0.001). There was no significant difference in the prevalence of polysensitization among different age groups, but sensitization to both inhalant and food allergens significantly increased with age. CONCLUSION: Our results suggest that specific IgE tests to common inhalant allergens, particularly the house dust mites, may be considered when performing blood screening tests for young children presenting with symptoms and/or signs of allergic diseases.

Preparation and Characterization of an Extract of German Cockroach From a Korean Source

PURPOSE: The cockroach (CR) is an important cause of respiratory allergic disorders. We prepared a German CR extract in a standardized way and analyzed its allergenic properties. METHODS: The extract was prepared from German CR (Blattella germanica) obtained from a Korean colony, and its allergenic activity was compared with that of the commercial Hollister-Stier (HS) extract. The concentrations of Bla g 1 and Bla g 2 were measured, and an in vitro specific IgE binding inhibition assay was performed to assess IgE reactivity. Proteolytic activity was examined by gelatin zymography. RESULTS: Bla g 1 and Bla g 2 were detected at 405 U/mg and 273 ng/mg, respectively, in the Korean extract, and at 187 U/mg and 56 ng/mg, respectively, in the HS extract. The Korean extract showed 94.2% inhibition of IgE reactivity, as compared with the HS extract. A similar pattern of IgE-reactive bands was detected for the two extracts, indicating that their allergenic components are similar. The proteolytic activities of the Korean and HS extracts were found to be similar in gelatin zymography. The endotoxin levels in the Korean and HS extracts were 3,440 EU/mL and 6,580 EU/mL, respectively. CONCLUSIONS: The German CR extract was prepared in a standardized way. The extract produced in this study will be useful for the development of allergy diagnostics and immunotherapeutic agents.

The Cockroach and Allergic Diseases

The cockroach represents one of the most common sources of indoor allergens worldwide, and 40%-60% of patients with asthma in urban and inner-city areas possess IgE antibodies to cockroach allergens. In Korean homes, four cockroach species have been found, of which the most commonly encountered is the German cockroach. The pathogenic mechanism underlying the association between cockroach allergens and allergic diseases has not been fully elucidated. Allergenicity is associated with the cockroach allergens themselves, enzymatic protease activity, and ligands for pattern recognition receptors. Although allergen-specific adaptive immune responses orchestrate the cockroach allergic response, recent data suggest that the innate immune system is also a critical contributor to pathogenesis. We review the current evidence for the demographics of cockroach exposure and sensitization, characteristics of cockroach allergens, and inflammatory responses to cockroach allergens initiated through protease-dependent pathways.

A new species of Neoblattella Shelford (Blattellidae: Pseudophyllodromiinae) from Amazonas State, Brazil

Neoblattella mista sp. nov. is described and illustrated based on male genitalia and morphological characters of a single specimen collected in the town of Coari, State of Amazonas, Brazil. By studying the literature on the genus, we determined that N. mista sp. nov. differs from the other four known complexes in the morphology of its genital structures, including the supra-anal plate, subgenital plate, right and left phallomeres, median genital sclerite and tergal modification in the abdomen, and is placed in the new "mista complex".

Differential susceptibility of adults and nymphs of Blattella germanica (L.) (Blattodea: Blattellidae) to infection by Metarhizium anisopliae and assessment of delivery strategies

Microbial insecticides for cockroach control, such as those containing entomopathogenic fungi, may be an alternative to reduce contamination by chemicals in housing and food storage environments. Virulence of isolate ESALQ1037 belonging to the Metarhizium anisopliae complex against nymphs and adults of Blattella germanica (L.), and its infectivity following exposure of insects to a contaminated surface or to M. anisopliae-bait were determined under laboratory conditions. Estimated LD50 15 d following topical inoculation was 2.69 x 10(5) conidia per adult, whereas for nymphs the maximum mortality was lower than 50 percent. Baits amended with M. anisopliae conidia had no repellent effect on targets; adult mortality was inferior to 25 percent, and nymphs were not susceptible. All conidia found in the digestive tract of M. anisopliae-bait fed cockroaches were unviable, and bait-treated insects that succumbed to fungal infection showed a typical mycelial growth on mouthparts and front legs, but not on the hind body parts. As opposed to baits, the use of a M. anisopliae powdery formulation for surface treatment was effective in attaining high mortality rates of B. germanica. Both nymphs and adults were infected when this delivery strategy was used, and mycelia growth occurred all over the body surface. Our results suggest that the development of powders or similar formulations of M. anisopliae to control B. germanica may provide faster and better results than some of the strategies based on baits currently available.

Mortalidade de Blattella germanica (L., 1767) (Blattodea: blattellidae) sob diferentes áreas e períodos de exposição a diferentes inseticidas / Mortality of Blatella germanica under different exposure area and duration to insecticides

A maior importância das baratas como praga domiciliar é devida ligada à sua capacidade de disseminar microorganismos nocivos ao homem e à outros animais. Durante o dia repousam em ambientes sépticos, escuro, úmidos e quentes como em esgotos. À noite exploram armazéns e cozinhas ou locais de manipulação e depósito de alimentos como padarias, restaurantes, hospitais e residências que requerem higienização constante. Neste trabalho objetivou-se avaliar a mortalidade de Blattella germanica (L., 1767) (Blattodea: Blattellidae) em laboratório sob diferentes períodos e áreas de exposição em superfícies tratadas com inseticidas. Os testes foram realizados no Departamento de Fitossanidade da UNESP, Campus de Jaboticabal, SP. A aplicação dos inseticidas foi realizada em torre de Potter sobre placas de Petri, em três tempos de exposição (2, 8 e 32 min) e quatro áreas de exposição (25, 50, 75 e 100%). Foram utilizados os inseticidas piretróides gamacialotrina, deltametrina, lambdacialotrina, alfacipermetrina e cipermetrina e o carbamato bendiocarb, nas dosagens recomendadas pelos fabricantes, comparados a uma testemunha sem aplicação. Foram confinadas cinco baratas adultas sobre a placa para os dois experimentos. A avaliação da mortalidade foi realizada 0, 1, 2, 4, 24, 48 e 72 horas após confinamento na superfície tratada. Para o período de exposição, os produtos resultaram em uma boa eficiência e para “área de exposição” o inseticida cipermetrina apresentou uma maior mortalidade. Em relação aos períodos de exposição, todos tempos resultaram em uma mortalidade eficiente. Para a área de exposição, a maior mortalidade foi observada para a aplicação do produto na área total.

The great importance of cockroaches as household pest have been on their ability to spread microorganisms harmful to humans and animals. Rest during the day in dark, humid and hot as sewerage. At night go into stores and kitchens or places to deposit and manipulation of food as bakeries, restaurants, hospitals and homes wich requires clinig operations. This work aimed to evaluate mortality of B. germanica (L., 1767) (Blattodea: Blattellidae) under different periods and exposure area treated by insecticides in laboratory. The tests were carried out at Department of Fitossanidade at UNESP, Campus of Jaboticabal, SP, Brasil. The insecticides were applied by Potter's tower sprayer on Petri dishes. Three times of exposure (2, 8 and 32 min) and four exposure areas (25, 50, 75 and 100%) and volume of 0,5 ml for the second experiment were tested. It was used the insecticides Pyrethroids gammacyalothrine, deltamethrine, lambdacialothrine, alfacipermethrine, cipermethrine and carbamates bendiocarb, in the dosages recommended by the manufacturers, and I was used control without application. Five adult cockroaches was confined in the dishes for both experiments. The mortality evaluation was done 0, 1, 2, 4, 24, 48 and 72 hours after of the confinement on the treated surface. It was concluded that for exposure duration experiment all the insecticides have a good efficiency. The exposure area experiment the insecticide cipermethrine was what the one which had the higher mortality. Regarding to the effect of exposure duration on the accumulated mortality every duration times had a high mortality. In relation to the exposure area the highest mortality reached to 100% of treated area.

[Susceptibility level of hospital-collected strains of German cockroach Blattella germanica [L.] to carbamate and organophosphorous insecticides using surface contact method in Tehran [2007-2008]]

The German cockroach, Blattella germanica [L], is a worldwide hygienic pest that is very difficult to control. Extensive usage of insecticides may develop resistance to variety of insecticides, causing failure to control. This study was designed to determine resistance of hospital-collected strains of the German cockroach to carbamate and organophosphorous insecticides. The insecticide resistance status in nine hospital- collected strains of the German cockroach, Blattella germanica [L.] gainst two carbamate insecticides [bendiocarb, carbaryl] and two organophosphorous insecticides [malathion, chlorpyriphos] were detected using glass jar test method. For detection of resistance in adult males the susceptibility level of each field strain was compared with standard susceptible strain based on the mortality rate obtained from exposing them to a single discriminating dose. The results of mortality test of four insecticides on adult males of susceptible strain demonstrated the discriminating doses for chlorpyriphos [6.63 mg/m2], bendiocarb [66.34 mg/m2]and carbaryl [390.11 mg/m2] respectively. The lowest and highest discriminating doses belonged to chlorpyriphos and carbaryl respectively. Among nine adult males strains two strains were resistant to bendiocarb and two strains were resistant to carbaryl. Some strains also showed a wide range of tolerance to malathion and chlorpyriphos. The study proposed the carbamate insecticides [bendiocarb and carbaryl] did not have efficacy for control of German cockroach due to development of resistance in the strains. Our results showed that the resistance to organophosphorous insecticides is developing, consequently, the usage of these insecticides is not recommended. Investigation on chlorpyriphos resistance mechanisms is suggested for the possibility of rotational usage of this compound with pyrethroid insecticides could be evaluated

Atopy Patch Tests for Atopic Dermatitis Patients according to the Concentration and Vehicle for the Cockroach Antigen / 대한피부과학회지

BACKGROUND:Recent studies have attempted to document the correlation of an atopy patch test (APT) and a skin prick test. The results have suggested a possible role of delayed allergic reaction in the development of eczematous skin lesions in patients with atopic dermatitis (AD) OBJECTIVE: The aim of this study was to evaluate the relationship of APT with skin prick test and specific IgE for cockroach antigen. And we attempted to find the optimal vehicle and concentration of APT for cockroach allergy in AD patient. METHODS: We performed APTs in 50 patients with AD with using German cockroach allergens (the extract with different concentrations and vehicles). The reactions were evaluated after 48 hours, and these were compared with the results of the skin prick test and the total and specific IgE levels. RESULTS: The AD patients who had cockroach allergy, according to a skin prick test or the specific IgE level, showed higher positive APT reactionsthan the non-allergic patients to cockroach. The APT reactions showed a significant relationship with the skin prick test and the specific IgE level (85.7%). With regard to the form of cockroach antigen, a positive APT was more frequent with using the powder form that with using the extract. Regarding the vehicle, petrolatum induced higher positive APT reactions than did distilled water. There was a close relationship between the antigen concentration in petrolatum base and a positive APT reaction. Ten and fifty percent cockroach antigen elicited positive APT reactions than did 1% cockroach antigen with using a petrolatum base. CONCLUSION: Petrolatum is an optimal vehicle for an APT for cockroach because an APT with a petrolatum base revealed the highest correlation with cockroach allergy. The dose-response relationship between antigen concentration and the frequencies of positive APT reactions demonstrated that 10% and 50% cockroach antigen is superior to 1% cockroach antigen.

Espécies novas de Chromatonotus Hebard, 1920 da região da Amazônia (Blattellidae, Blattellinae) / New species of Chromatonotus Hebard, 1920 from the Amazon region (Blattellidae, Blattellinae)

Duas espécies novas de Chromatonotus Hebard, 1920 do estado de Mato Grosso, Brasil, são descritas: Chromatonotus chirostylatus sp. nov e Chromatonotus sinopensis sp. nov. Ilustrações sobre a forma e coloração, modificação tergal no abdome, placas genitais e peças da genitália do macho são apresentadas.

Two new species of Chromatonotus Hebard, 1920 from Mato Grosso State, Brazil, are described: Chromatonotus chirostylatus sp. nov and Chromatonotus sinopensis sp. nov. Illustrations of the shape and coloration, tergal modification in the abdome, genital plates and the male genitalia are presented.

Cloning of a Family of Serine Protease Genes Expressed in German Cockroach(Blattella germanica) and Possibility as Allergens / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: The serine protease allergens have been known as one of the most important inhalent allergens of insects as well as house dust mites. There is no known serine protease allergen of German cockroach, which is a well-known etiological agent of allergic diseases. We identified the serine protease genes of cockroach, Blattella germanica, and examined its possibility as an allergen. MATERIALS AND METHOD: We have isolated three partial genes, Bg3, Bg5 and Bg6, of serine protease from the Blattella germanica cDNA library using the degenerate oligonucleotide PCR primers specific for the conserved regions. RESULTS: The genes, Bg3, Bg5 and Bg6, were composed of 396 bp 131 amino acids, 513 bp 170 amino acids, and 410 bp 136 amino acids, respectively. Northern hybridization analysis indicated that the size of Bg5 and Bg6 transcripts was approximately 0.7 kb. The gene, Bg5, was also identified as a multiple gene by the Southern blot analysis. The gene, Bg3, showed significant homology to trypsin-like serine protease of various insects. The deduced amino acids sequence of the gene Bg5 was matched to the mite group III allergen as well as various species of insect serine protease sequences. The gene Bg6 also showed high homology to the amino acids sequences of insect serine proteases and mite group III allergens. Three Blattella germanica serine protease gene fragments revealed close genetic relationships with Dermatophagoides farinae group III allergen in the phylogenetic analysis. CONCLUSION: The high homology and close phylogenetic relationship raise the possibility of three serine protease genes as being an allergen of German cockroach.

Rapid elimination of German cockroach, Blatella germanica, by Fipronil and Imidacloprid gel baits

Baits have become popular and effective formulations against urban insect pests. Compared with residual sprays toxic gel baits are used more and more frequently to control urban cockroach populations. The aim of this study was to investigate the usage of two commercially available fipronil and imidacloprid gel bait formulations against Blattella germanica field infested in Iran. The study was carried out in an urban area at Tehran from March 2004 to September 2005. The 0.05% fipronil and 2.15% imidacloprid gel baits were placed continuously in 3 residential German cockroach infested units. Pre- and post-treatment cockroach density was assessed by visual count method. Pre- and post-treatment visual count of cockroaches in treatment and control areas, and percentage reduction in cockroach density in treatment areas in comparison to control areas was showed that density reduction was increased with the 0.05% fipronil and 2.15% imidacloprid gel baits in treated areas from 1st to 9th week in comparison to control area. After 60 days, German cockroaches eliminated completely from these areas. These results show that fipronil and imidacloprid gel baits are highly effective in field German cockroach infested after insecticide spraying control failure German cockroach infested fields where spraying of pyrethroid insecticides failed to control the situation and confirm previous reports stating that avermectin and hydramethylnon are more effective than conventional insecticides in baits against cockroaches. Therefore, fipronil and imidacloprid gel baits are appropriate candidates for controlling German cockroach infested dwellings in Iran where control with other insectices failed because of resistance

Determinación de la resistencia a insecticidas y mecanismos de resistencia en cepas de Blattella germanica (Dictyoptera: Blattellidae) / Determination of insecticide-resistance and resistance mechanisms of Blattella germanica (Dictyoptera: Blattellidae)

Se evaluaron los niveles de resistencia en 3 cepas de Blattella germanica colectadas en diferentes lugares de Ciudad de La Habana, frente a 4 insecticidas. Las cepas fueron resistentes a los 2 piretroides evaluados (cipermetrina y lambdacialotrina) y al organofosforado malatión, mostrándose susceptibles ante el carbamato propoxur. Se determinaron los valores α y ß Esterasas, acetilcolinesterasa y glutation S-transferasa, a ejemplares de las 3 cepas involucradas en el estudio. Los resultados del trabajo mostraron una elevada actividad de esterasas en todas las cepas, sobre todo de las ß Esterasas, en 2 de las 3 cepas estudiadas la enzima glutation S-transferasa fue elevada y no se demostró que existan modificaciones en la acetilcolinesterasa en relación con la cepa de referencia. La relación entre los niveles de resistencia a insecticidas, los posibles mecanismos de resistencia presentes en cada cepa y los resultados de la actividad enzimática, fueron analizados.

In this paper, the level of resistance to four insecticides of 3 Blatella germanica strains collected from various places in the City of Havana province was evaluated. These strains were resistant to two pyrethroids (cypermethrin and lambdacyalothrine) and to organophosphorate malathion but susceptible to carbamate propoxur. The values of α and ß esterases, acetylcholinesterase and gluthatione-S-transferase were estimated in three strains involved in the study. The results of the study showed high esterase activity in all the strains, mainly ß esterases and two of the three strains presented with high gluthation-S-transferase enzyme. No changes in acetylcholinesterase were demonstrated in relation to the reference strain. The association of levels of resistance to insecticides, the possible resistance mechanisms in each strain and the results of the enzymatic activity were also analyzed.

Composición química y efecto letal del aceite esencial de Pimenta racemosa (Myrtales: Myrtaceae) sobre Blattella germanica (Dictyoptera: Blattellidae) / Chemical composition and lethal effect of essential oil from Pimenta racemosa (Myrtales: Myrtaceae) on Blatella germanica (Dictyoptera: Blattellidae

Se examinó mediante un análisis GC y GC-MS (cromatografía gaseosa-espectrometría de masa), el aceite esencial extraído de hojas de Pimenta racemosa (Mill.) J.W. Moore (Myrtales: Myrtaceae). Se identificaron un total de 26 compuestos volátiles que representaron 99,5 por ciento de la composición total; los de mayor proporción resultaron el terpinen-4-ol y 1,8-cineol. Se realizaron bioensayos al nivel de laboratorio con 5 dosificaciones de este aceite sobre la cucaracha Blattella germanica, se encontraron valores de DL50= 15,55 por ciento y DL95= 48,16 por ciento mediante un análisis probit-log, así como una dosis diagnóstica de 2 µg/insecto del aceite a 50 por ciento, que se propone para la vigilancia en el terreno del uso de formulaciones en programas de lucha contra este insecto.

Gas chromatography test and Gas chromatography/mass spectrometry test allowed examining the essential oil from Pimenta racemosa leaves (Mill.) J.W. Moore (Myrtales: Myrtaceae). A total of 26 volatile compounds representing 99.5 percent of the whole composition were identified, being ternipen 4-ol and 1,8 cineol those having the largest portions. Lab bioassays were performed with 5 different oil doses on Blattella germanica. DL50=15.55 and DL95=48.16 percent were estimated by a probit-log analysis as well as diagnostic dose of 2 µg/insect of 50 percent oil that is recommended for field surveillance of the use of various formulations in insect control programs.

Field performance of imidacloprid gel bait against German cockroaches (Dictyoptera: Blatellidae).

BACKGROUND AND OBJECTIVES: Resistance amongst cockroaches has been reported to most of the spray insecticides. Imidacloprid gel baits, which can be selectively applied at the infested and potential harborages sites have been found effective in control of cockroach infestation in some laboratory studies but very few field studies are available. This study was therefore undertaken to evaluate the efficacy of imidacloprid gel bait in the control of German cockroaches (Blatella germanica) in field. METHODS: A survey was done to find out pre-treatment density in 12 cookhouses by visual count and sticky trap method. A total of four cookhouses having high cockroach infestation were selected by simple random sampling method (two for imidacloprid treatment and two for control). Imidacloprid gel (2.15%) was used as crack and crevices treatment at the infested sites and potential harborages once only during the entire study duration. Post-treatment density was assessed by visual count method every week for nine weeks. RESULTS: Visual count method gave better indications of cockroach infestation as compared to sticky trap method, hence the same was followed for post-treatment evaluation. Reduction of 75.0 - 86.5 per cent was achieved with imidacloprid gel treatment by week 1 post-treatment in comparison to control areas. The reduction in treated areas by 8 wk post-treatment was 96.3-98.8 per cent in comparison to control areas. Residual effect of imidacloprid started declining at 9 wk (91.7 - 96.5% reduction in comparison to control areas). INTERPRETATION AND CONCLUSION: The results of our study report the efficacy of imidacloprid gel bait (2.15%) up to 8 wk against German cockroaches. The gel was safe and environment friendly also.

Comparison of Permethrin and Fipronil toxicity against German cockroach [Dictyoptera: Blattellidae] strains

Control of insect pests of agriculture, economic, and medical importance usually focuses on the use of insecticides. The susceptibility levels of eleven strains of German cockroaches, Blattella germanica [L.], were compared with a standard susceptible strain against permethrin and fipronil. The strains were collected from nine infested students' dormitories and two infested hospitals in Tehran, capital of Iran. The susceptible strain showed LD50 of 0.43 micro g and 0.96 ng for permethrin and fipronil respectively. Comparison of the resistance ratio of collected strain with susceptible strain showed resistance ratios of 8.6 to 17.7-folds for permethrin and 1.5 to 2.6-folds for fipronil, respectively. The result of this investigation indicated that the all strains were resistant to permethrin. Resistance spectrum of fipronil to permethrin showed different pattern of susceptibility to fipronil, indicating that there was no relationship between resistance to permethrin and fipronil