RESUMEN
Tergal glands are found in many insect species and contain constituents such as pheromones, sugars, proteins, and so forth. Preliminary studies have revealed that tergal gland secretions in the German cockroach (Blattella germanica L.) contain the human allergen Bla g 2 (B. germanica allergen 2), an inactive aspartic protease. Although Bla g 2 protein expression has been detected previously in various German cockroach body parts, including male tergal glands, studies that link protein expression in various life stages and tissues with mRNA and protein abundance have not been conducted. Therefore, the goal of this study was to measure the relative abundances of Bla g 2 protein and mRNA in different tissues and life stages of B. germanica using immunoblotting, quantitative PCR, and liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based quantitative profiling. We found that Bla g 2 protein was detected in every sampled tissue, including the male tergal glands. Protein abundance was relatively high in adult males and their tergal glands in comparison to nymphs and virgin females. Similarly, Bla g 2 mRNA transcript levels were also comparatively higher in male tergal glands and adult males. In conclusion, this study provides new information on the relative abundance and distribution of Bla g 2 allergen, a medically significant protein, in different tissues and developmental stages of the German cockroach and lays the foundation for future studies that aim to determine the function of this protein in B. germanica development.
Asunto(s)
Alérgenos , Blattellidae , Alérgenos/genética , Alérgenos/metabolismo , Animales , Ácido Aspártico Endopeptidasas/genética , Ácido Aspártico Endopeptidasas/metabolismo , Blattellidae/genética , Blattellidae/metabolismo , Cromatografía Liquida , Femenino , Masculino , ARN Mensajero/genética , ARN Mensajero/metabolismo , Espectrometría de Masas en TándemRESUMEN
Plant essential oils (EOs) are secondary metabolites derived from aromatic plants that are composed of complex mixtures of chemical constituents. EOs have been proposed as one of the alternative methods for bed bug (Cimex lectularius L.) control. In insecticide resistant mosquitoes and tobacco cutworm, EOs synergize pyrethroid toxicity by inhibiting detoxification enzymes. However, whether EOs and their constituents enhance pyrethroid toxicity in C. lectularius has remained unknown. Therefore, this study was designed to (i) determine the effects of binary mixtures of deltamethrin (a pyrethroid insecticide) with EOs or EO constituents or EcoRaider® (an EO-based product) on mortality of insecticide resistant and susceptible bed bugs, and (ii) evaluate the effects of EO constituent pre-treatment on detoxification enzyme activities of resistant and susceptible populations. Topical bioassays with binary mixtures of deltamethrin and individual EOs (e.g., thyme, oregano, clove, geranium or coriander oils) or their major constituents (e.g., thymol, carvacrol, eugenol, geraniol or linalool) or EcoRaider® at doses that kill approximately 25% of bed bugs caused significant increases in mortality of resistant bed bugs. However, in the susceptible population, only coriander oil, EcoRaider®, thymol, and carvacrol significantly increased the toxicity of deltamethrin. Detoxification enzyme assays with protein extracts from bed bugs pre-treated with EO constituents suggested selective inhibition of cytochrome P450 activity in the resistant population, but no impacts were observed on esterase and glutathione transferase activities in either population. Inhibition of P450 activity by EO constituents thus appears to be one of the mechanisms of deltamethrin toxicity enhancement in resistant bed bugs.
Asunto(s)
Chinches , Insecticidas , Aceites Volátiles , Piretrinas , Animales , Sistema Enzimático del Citocromo P-450 , Resistencia a los Insecticidas , Insecticidas/toxicidad , Nitrilos , Aceites Volátiles/toxicidad , Piretrinas/toxicidadRESUMEN
Pyrethroid resistance has been a major hurdle limiting the effective control of bed bugs (Cimex lectularius L.). Alternative approaches that include the use of plant essential oils (EOs) have been proposed for effective management of bed bugs. However, EO resistance level comparisons between pyrethroid susceptible and resistant bed bug populations have not been previously conducted. The goal of this study was twofold: (i) determine deltamethrin resistance levels and associated resistance mechanisms in the field-collected Knoxville strain and (ii) quantify resistance levels of the Knoxville strain to five EOs (thyme, oregano, clove, geranium and coriander), their major insecticidal constituents (thymol, carvacrol, eugenol, geraniol and linalool) and an EO-based product (EcoRaider®). First, we found that the Knoxville strain was 72,893 and 291,626 fold more resistant to topically applied deltamethrin in comparison to the susceptible Harlan strain at the LD25 and LD50 lethal dose levels, respectively. Synergist bioassays and detoxification enzyme assays revealed significantly higher activity of cytochrome P450 and esterase enzymes in the resistant Knoxville strain. Further, Sanger sequencing revealed the presence of the L925I mutation in the voltage-sensitive sodium channel α subunit gene. The Knoxville strain that possesses both enzymatic and target site deltamethrin resistance, however, did not show any resistance to EOs, their major insecticidal constituents and EcoRaider® in topical bioassays (resistance ratio of ~1). In conclusion, this study demonstrated that a deltamethrin-resistant strain of bed bugs is susceptible to EOs and their insecticidal constituents.
Asunto(s)
Chinches/efectos de los fármacos , Insecticidas/farmacología , Aceites Volátiles , Piretrinas , Animales , Resistencia a los Insecticidas/efectos de los fármacos , NitrilosRESUMEN
Insecticides that are used for pest control undergo physical and biological (enzymatic) degradation. Indoxacarb is an oxadiazine class sodium channel blocker insecticide used for German cockroach (Blattella germanica L.) control. At present, no information is available on enzymatic biotransformation or metabolism of indoxacarb in this important urban pest. We studied the biotransformation pathways of indoxacarb in one susceptible and three field strains with varying susceptibility levels using liquid chromatography and high-resolution mass spectrometry. As shown in other insect species we found evidence for hydrolase-based bioactivation of indoxacarb to a toxic decarbomethoxylated metabolite, DCJW. In addition, both indoxacarb and DCJW were further metabolized to hydroxy, oxadiazine ring-opened and hydroxylated ring-opened metabolites. In general, higher indoxacarb disappearance, increased formation of DCJW and the above-mentioned metabolites were observed in the three field strains. In vitro biotransformation studies showed that hydroxylated and oxadiazine ring-opened metabolite formation is NADPH/cytochrome P450-dependent. Bioassays and in vivo metabolism experiments using the enzyme-inhibiting insecticide synergists, piperonyl butoxide (PBO) and S,S,S,-tributyl phosphorotrithioate (DEF), provided insights into potential indoxacarb resistance mechanisms that may proliferate in German cockroach field strains following unchecked selection pressures. The information presented here is an essential step toward developing indoxacarb resistance management programs and also reveals mechanisms of secondary/tertiary indoxacarb toxicity.
Asunto(s)
Blattellidae/metabolismo , Insecticidas/farmacocinética , Oxazinas/farmacocinética , Animales , Biotransformación , Inhibidores Enzimáticos del Citocromo P-450/farmacología , Masculino , Organotiofosfatos/farmacología , Sinergistas de Plaguicidas/farmacología , Butóxido de Piperonilo/farmacologíaRESUMEN
Turmeric is an important spice crop with documented human health benefits associated with chemicals called curcuminoids. In this study, the termite Reticulitermes flavipes (Kollar) was exposed to different solvent extracts of turmeric to investigate potential termiticidal properties. Treating termites with hexane extracts of purified lab-grade curcuminoids had no effect on termites. However, in continuous exposure assays, the LC(50) for hexane extracts of crude turmeric powder was 9.6 mg, or 1.0 mg starting material per square centimeter of filter paper substrate. These active components were soluble in a range of polar and apolar solvents, but only hexane could selectively fractionate active components away from the inactive curcuminoids. The active constituents of turmeric separated by thin layer chromatography (TLC) fluoresced in short-wave UV light but were not visible in long-wave UV light. By re-extracting TLC-separated bands in hexane and performing bioassays and gas chromatography-mass spectrometry, we demonstrated that termiticidal components of turmeric are extractable as a blend containing mainly ar-turmerone, turmerone, and curlone. This determination is consistent with findings of preceding work by other researchers that investigated insecticidal properties of turmeric in other pest insects.
Asunto(s)
Curcuma , Insecticidas , Isópteros , Extractos Vegetales , Animales , Dosificación Letal MedianaRESUMEN
Many gregarious insect species use aggregation and alarm pheromones. The bed bug, Cimex lectularius L., emits an alarm pheromone (AP), a 70/30 blend of (E)-2-hexenal and (E)-2-octenal, when threatened. Bed bugs avoid temperatures above 43 °C, which are lethal to bugs and used commercially as spatial heat treatments to manage infestations. However, the interaction of bed bug AP in heat avoidance has not been investigated. The goal of this research was to: 1) determine if bed bugs emit AP as an alarm response to heat exposure, and 2) quantify the behavioral responses of conspecifics to AP emitted by heat-exposed bed bugs. Using a selected ion flow tube mass spectrometer, we found that bed bugs responded to lethal and sublethal heat exposure by emitting AP. The Harlan laboratory population emitted more pheromone than a laboratory adapted field population from Florida (McCall). Harlan females emitted the most AP, followed by Harlan males, McCall females and males. In separate behavioral experiments, we showed that conspecifics (i.e., recipients) reacted to AP released by heat exposed bed bugs (i.e., emitters) by frantically moving within 50 mm and 100 mm test arenas. The Harlan recipients reacted to AP in 100 mm areas, whereas the McCall strain did not, indicating a short area of effectiveness of the AP. Synthetic AP components tested in behavioral experiments caused identical effects as the natural AP blend released by heat-exposed bed bugs.
Asunto(s)
Aldehídos , Chinches , Infestaciones Ectoparasitarias , Femenino , Masculino , Animales , Calor , Causalidad , FeromonasRESUMEN
Indoxacarb, a sodium channel-blocking insecticide, has been in widespread use for German cockroach control in the United States since 2006. A two-tiered indoxacarb susceptibility monitoring strategy was previously developed as a first step toward determining indoxacarb susceptibility levels in German cockroach field populations. This strategy entails: (tier 1) testing field-collected populations in vial bioassays at two diagnostic concentrations; and (tier 2) testing populations at three diagnostic doses in oral (feeding) bioassays with treated bait matrix. In the current study the two-tiered technique was implemented to evaluate field (n = 14) and susceptible laboratory (n = 2) strains collected from 13 different U.S. locations. Our hypothesis was that at least some of the field-collected populations would display significant survivorship in both bioassays relative to susceptible laboratory populations. In agreement with this hypothesis, significantly reduced susceptibility was detected in 13 and 7 field strains with vial and feeding bioassays, respectively. In general, the lower number of strains displaying reduced susceptibility in feeding bioassays (seven strains) supports previous findings that indoxacarb is more toxic via ingestion. Although these findings suggest a reduced risk for resistance selection via feeding on indoxacarb-containing baits, they also suggest a need for proactive resistance management with respect to both spray and bait products.
Asunto(s)
Blattellidae/efectos de los fármacos , Control de Insectos/métodos , Insecticidas/farmacología , Oxazinas/farmacología , Animales , Blattellidae/genética , Resistencia a los Insecticidas/efectos de los fármacos , Selección GenéticaRESUMEN
The German cockroach, Blattella germanica (L.), is one of the most critical urban pests globally due to the health risks it imposes on people, such as asthma. Insecticides are known to manage large cockroach population sizes, but the rapid rate at which they develop resistance is a continuing problem. Dealing with insecticide resistance can be expensive and time-consuming for both the consumer and the pest management professional (PMP) applying the treatment. Each cockroach population is unique because different strains have different insecticide susceptibilities, so resistance profiles must be considered. This study addressed the above issue in a controlled laboratory setting. Cockroach strains from Indianapolis, Indiana, Danville, Illinois, and Baltimore, Maryland, USA were used. Four insecticide active ingredients (AIs) most used by consumers and PMPs were selected for testing in vial bioassays to establish resistance profiles. Next, no-choice and choice feeding assays with four currently registered bait products were performed to assess the impacts of competing food and circadian rhythms on bait resistance levels. The results indicate that emamectin benzoate (Optigard) was the most effective AI in causing the highest mortality in all strains in vial and no-choice bioassays; whereas, the other AIs and products were more impacted by resistance. The results acquired from these studies can help develop rapid tests for use by PMPs based on the no-choice feeding assay while also adding more information supporting current resistance and cross-resistance evolution theories.
Asunto(s)
Blattellidae , Insecticidas , Animales , Insecticidas/farmacología , Resistencia a los Insecticidas , Control de Insectos/métodos , Bioensayo , AlérgenosRESUMEN
German cockroaches (Blattella germanica L.) have significant impacts on human health, most notably they are implicated as causes of childhood asthma. Gel bait formulations of fipronil, a phenylpyrazole insecticide, have been in use for German cockroach control in the United States since 1998. Previously, dieldrin resistant German cockroach strains were shown to have 7- to 17-fold cross-resistance to fipronil. More recently, a field-collected strain (GNV-R) displayed approximately 36-fold resistance to topically applied fipronil at the LD50 level, which is the highest level of fipronil resistance reported to date in the German cockroach. The aim of the current research was to identify mechanism(s) responsible for high-level fipronil resistance in the GNV-R strain. Synergist bioassays conducted using topical and injection application methods implicated cytochrome P450-mediated detoxification in resistance. Electrophysiological recordings using the suction-electrode technique revealed the nervous system of the GNV-R strain is insensitive to fipronil. In agreement with electrophysiology results, the alanine to serine (A302S) mutation encoded by the gamma-amino butyric acid-gated chloride channel subunit gene resistance to dieldrin, which confers limited cross-resistance to fipronil, was detected in 95% of GNV-R strain individuals. Logistic regression analysis showed that A302S mutation frequency correlates with neurological insensitivity as shown by electrophysiology data. Overall, results of synergism bioassays, electrophysiological recordings, and A302S mutation frequency measurements suggest that fipronil resistance in the GNV-R strain is caused by the combined effects of enhanced metabolism by cytochrome P450s and target-site insensitivity caused by the A302S-encoding mutation in the resistance to dieldrin gene.
Asunto(s)
Blattellidae/efectos de los fármacos , Resistencia a los Insecticidas , Insecticidas/farmacología , Pirazoles/farmacología , Animales , Blattellidae/genética , Resistencia a los Insecticidas/genética , Mutación , Sinergistas de Plaguicidas/farmacología , Polimorfismo GenéticoRESUMEN
BACKGROUND: Heat can be effective for bed bug elimination. However, in some cases bed bugs survive heat treatments. The objectives of this study were to determine the behavioral responses of bed bugs to rising harborage temperatures (23.0-49.0 °C) and identify which heat shock protein (HSP) genes are expressed after heat exposure. First, a custom-made copper arena and harborage were used to determine the escape behaviors of six bed bug populations. Next, HSP gene expression responses of select populations were determined after heat exposure using real time quantitative polymerase chain reaction (RT-qPCR). RESULTS: Analysis of the 25 min behavioral experiment data found that harborage top temperatures associated with 25%, 50% and 75% probabilities of bed bugs to flee the harborage did not differ significantly between populations. Also, the percentage of insects that escaped from heated areas and survived (4.0-12.0%) was not different between populations. However, when specific temperatures at which successful escapes occurred were statistically compared, the Poultry House population was found to flee the harborage at statistically higher temperatures (43.6 ± 0.5 °C) than others (40.5 ± 0.6-42.0 ± 0.7 °C). The RT-qPCR experiments revealed that the HSP70.1, HSP70.3, and Putative Small HSP genes were significantly up-regulated 15 min, 2, and 4 h post-heat exposure and decreased back to baseline levels by 24 h. CONCLUSIONS: This study shows that when harborage top temperatures approach 40.0-43.0 °C, bed bugs will disperse in search for cooler areas. This work implicates the HSP70.1, HSP70.3, and Putative Small HSP genes in heat induced stress recovery of bed bugs. © 2021 Society of Chemical Industry.
Asunto(s)
Chinches , Infestaciones Ectoparasitarias , Animales , Chinches/genética , Expresión Génica , Proteínas de Choque Térmico/genética , CalorRESUMEN
Effective control of domestic and peridomestic cockroaches requires integrated approaches that emphasize concurrent use of chemicals with alternative control tactics. An integrated pest management (IPM) approach is particularly justified in environments where satisfactory cockroach control cannot be achieved due to multiple factors including development of insecticide aversion and resistance in some cockroach species, and poor sanitation or structural issues that foster infestations. While a flurry of research effort has been devoted to study alternative tactics for cockroach control, only a few of them have been evaluated in the context of IPM programs. This review focuses on examining studies on alternative tactics that are proven efficacious, economical, and logistically feasible for their inclusion in IPM programs for important domestic and peridomestic cockroaches in the USA. Management programs that educate the public on cockroach biology, behavior, and the importance of sanitation; use of traps to monitor infestation levels; apply targeted low impact insecticides such as baits, have demonstrated a greater success for effective and sustainable control of cockroaches when compared to an insecticide-only approach. Incorporation of other alternative control methods to IPM programs will require more applied research that validates their use in real-world scenarios and demonstrates their cost-effectiveness.
RESUMEN
Cockroaches are important global urban pests from aesthetic and health perspectives. Insecticides represent the most cost-effective way to control cockroaches and limit their impacts on human health. However, cockroaches readily develop insecticide resistance, which can quickly limit efficacy of even the newest and most effective insecticide products. The goal of this research was to understand whole-body physiological responses in German cockroaches, at the metatranscriptome level, to defined insecticide selection pressures. We used the insecticide indoxacarb as the selecting insecticide, which is an important bait active ingredient for cockroach control. Six generations of selection with indoxacarb bait produced a strain with substantial (>20×) resistance relative to inbred control lines originating from the same parental stock. Metatranscriptome sequencing revealed 1,123 significantly differentially expressed (DE) genes in ≥two of three statistical models (81 upregulated and 1,042 downregulated; FDR P < 0.001; log2FC of ±1). Upregulated DE genes represented many detoxification enzyme families including cytochrome-P450 oxidative enzymes, hydrolases and glutathione-S-transferases. Interestingly, the majority of downregulated DE genes were from microbial and viral origins, indicating that selection for resistance is also associated with elimination of commensal, pathogenic and/or parasitic microbes. These microbial impacts could result from: (i) direct effects of indoxacarb, (ii) indirect effects of antimicrobial preservatives included in the selecting bait matrix, or (iii) selection for general stress response mechanisms that confer both xenobiotic resistance and immunity. These results provide novel physiological insights into insecticide resistance evolution and mechanisms, as well as novel insights into parallel fitness benefits associated with selection for insecticide resistance.
RESUMEN
Management of the common bed bug (Cimex lectularius L.) necessitates the use of multiple control techniques. In addition to synthetic pesticides and mechanical interventions, plant-derived essential oils represent one of the control options. Mixtures of two or more essential oil components (monoterpenoids) exhibit synergistic toxicity effects against insects due to increased cuticular penetration. Monoterpenoids, such as carvacrol, eugenol and thymol, are neurologically active and inhibit the nerve firing activity of C. lectularius. However, the effects of mixtures of these monoterpenoids on their toxicity and neuroinhibitory potential against C. lectularius are not known. In this study, the toxicity levels of a tertiary mixture of carvacrol, eugenol and thymol (1:1:1 ratio) and a binary mixture of synthetic insecticides, bifenthrin and imidacloprid (1:1 ratio) were evaluated against C. lectularius through topical bioassays and electrophysiology experiments. Both a mixture of monoterpenoids and the mixture of synthetic insecticides exhibited synergistic effects in topical bioassays. In electrophysiology experiments, the monoterpenoid mixture led to greater neuroinhibitory effects, whereas a mixture of synthetic insecticides caused higher neuroexcitatory effects in comparison to single compounds. This study shows evidence for neurological mechanisms of synergistic interactions between monoterpenoids and provides information regarding the utilization of natural compound mixtures for C. lectularius management.
RESUMEN
BACKGROUND: Ozone gas is commercially used for deodorization and microbial control. Its efficacy against stored product insect pests is well documented. In the midst of the common bed bug (Cimex lectularius L.) outbreak, claims were made that ozone gas was effective for their control. This study was conducted to determine baseline ozone concentrations and exposure times required for the control of an insecticide-susceptible C. lectularius strain under laboratory conditions. Dichlorvos (DDVP), an organophosphate class fumigant insecticide was used as a positive control. RESULTS: Nymphs and adults were more susceptible to ozone than eggs. Complete (100%) nymph and adult mortality was achieved at an ozone concentration (C) of 1500 ppm and exposure time (T) of 180 min, or concentration × time product (CT) of 270 000 ppm-min, whereas eggs required an eightfold higher CT (2 040 000 ppm-min). DDVP vapor was 2070-, 2542- and 450-fold more potent than ozone, against nymphs, adults and eggs, respectively. CONCLUSIONS: Baseline ozone toxicity data provide insights on the practicality of using this gas for the management of common bed bugs. High ozone CT products required for C. lectularius control, particularly eggs, suggest that its use for treating infested human dwellings is not feasible due to logistic, safety and monetary concerns. © 2020 Society of Chemical Industry.
Asunto(s)
Chinches , Insecticidas , Ozono , Animales , Humanos , Insecticidas/farmacología , Laboratorios , Ninfa , Ozono/farmacologíaRESUMEN
The field of urban entomology is primarily associated with the study of ants, bed bugs, cockroaches, termites, and other occasional invader pests that are found within or near human-made structures. A wide array of peer-reviewed studies were published in 2018. The topics of these articles ranged from genomes and basic biology of urban insects to various applied aspects of pest management. Key findings of these papers are presented and discussed from the perspective of the contributions they make to the discipline of urban entomology. Additionally, potential future research opportunities that are evident from these publications have been outlined.
Asunto(s)
Entomología , Control de Insectos , Ciudades , Población UrbanaRESUMEN
Bed bugs (Cimex lectularius L.) are globally important human parasites. Integrated pest management (IPM) approaches, which include the use of essential oil-based insecticidal compounds, have been proposed for their control. This study aimed to define insecticidal activity and neurophysiological impacts of plant essential oil constituents. The topical and fumigant toxicity of 15 compounds was evaluated against adult male bed bugs. Neurological effects of the 6 most toxicologically active compounds were also determined. In both topical and fumigant bioassays, carvacrol and thymol were the most active compounds. The potency of bifenthrin (a pyrethroid insecticide) in topical bioassays was 72,000 times higher than carvacrol, while vapors of dichlorvos (an organophosphate insecticide) were 445 times more potent than thymol. Spontaneous electrical activity measurements of the bed bug nervous system demonstrated neuroinhibitory effects of carvacrol, thymol and eugenol, whereas linalool produced an excitatory effect. Although citronellic acid and (±)-camphor increased baseline activity of the nervous system their effects were not statistically significant. Bifenthrin also caused neuroexcitation, which is consistent with its known mode of action. These comparative toxicity and neurological impact findings provide new information for formulating effective essential oil-based insecticides for bed bug IPM and conducting mode-of-action studies on individual essential oil components.
Asunto(s)
Chinches/efectos de los fármacos , Insecticidas/farmacología , Aceites Volátiles/farmacología , Aceites de Plantas/farmacología , Animales , Cimenos/farmacología , Diclorvos/farmacología , Eugenol/farmacología , Fumigación/métodos , Masculino , Sistema Nervioso/efectos de los fármacos , Timol/farmacologíaRESUMEN
The global population growth of the bed bug, Cimex lectularius (L.), is attributed to their cryptic behavior, diverse insecticide resistance mechanisms, and lack of public awareness. Bed bug control can be challenging and typically requires chemical and non-chemical treatments. One common non-chemical method for bed bug management is thermal remediation. However, in certain instances, bed bugs are known to survive heat treatments. Bed bugs may be present after a heat treatment due to (i) abiotic factors associated with the inability to achieve lethal temperatures in harborage areas for a sufficient time period, (ii) re-infestation from insects that escaped to cooler areas during a heat treatment or (iii) development of physiological resistance that allows them to survive heat exposure. Previous research has investigated the optimal temperature and exposure time required for either achieving complete mortality or sublethally affecting their growth and development. However, no research has examined bed bug populations for their ability to develop resistance to heat exposure and variation in thermo-tolerance between different bed bug strains. The goals of this study were: i) to determine if bed bugs could be selected for heat resistance under a laboratory selection regime, and ii) to determine if bed bug populations with various heat exposure histories, insecticide resistance profiles, and geographic origins have differential temperature tolerances using two heat exposure techniques (step-function and ramp-function). Selection experiments found an initial increase in bed bug survivorship; however, survivorship did not increase past the fourth generation. Sublethal exposure to heat significantly reduced bed bug feeding and, in some cases, inhibited development. The step-function exposure technique revealed non-significant variation in heat tolerance between populations and the ramp-function exposure technique provided similar results. Based on these study outcomes, the ability of bed bugs to develop heat resistance appears to be limited.
Asunto(s)
Chinches/fisiología , Animales , Fenómenos Bioquímicos/fisiología , Infestaciones Ectoparasitarias/fisiopatología , Calor , Control de Insectos/métodos , Resistencia a los Insecticidas/fisiología , Insecticidas/farmacología , Piretrinas/farmacologíaRESUMEN
The German cockroach (Blattella germanica L.) is a worldwide pest that lives exclusively in human environments. B. germanica threatens human health by producing asthma-triggering allergens, vectoring pathogenic/antibiotic-resistant microbes, and by contributing to unhealthy indoor environments. While insecticides are essential for reducing cockroach populations and improving health outcomes, insecticide resistance has been a consistent barrier to cockroach control since the 1950s. We conducted seminal field studies to compare three insecticide resistance intervention strategies for cockroaches and evaluated resistance evolution across multiple generations. Using pre-treatment resistance assessment to drive decisions, we found that single active ingredient (AI) treatments can successfully eliminate cockroaches if starting resistance levels are low. We further established that rotation treatments intuitively reduce selection pressure, and are effective when insecticides with no/low resistance are used. We also found that mixture products containing thiamethoxam + λ-cyhalothrin AIs were universally ineffective and highly repellent; and finally, evolution of cross-resistance among AIs is a significant, previously unrealized challenge.
Asunto(s)
Blattellidae/genética , Evolución Molecular , Resistencia a los Insecticidas/genética , Insecticidas , Alérgenos , Animales , Bioensayo , Vectores de Enfermedades , Vivienda , Illinois , Indiana , Control de Insectos , Nitrilos , Piretrinas , TiametoxamRESUMEN
Insecticide resistance in German cockroaches (Blattella germanica (L.)) has been a barrier to effective control since its first documentation in the 1950s. A necessary first step toward managing resistance is to understand insecticide susceptibility profiles in field-collected strains so that active ingredients (AIs) with lowest resistance levels can be identified. As a first step in this study, diagnostic concentrations (DCs) were determined for 14 insecticide AIs based on lethal concentrations that killed 99% or 90% of the individuals from a susceptible lab strain (JWax-S). Next, cockroaches were collected from two low-income multifamily housing complexes in Danville, IL, and Indianapolis, IN, and used to establish laboratory strains. These strains were screened against the 14 AI-DCs in vial bioassays, and susceptibility profiles were determined by comparing percent mortalities between the field strains relative to the JWax-S strain. Results revealed lowest resistance of field strains to boric acid, abamectin, dinotefuran, clothianidin, thiamethoxam, and chlorfenapyr. For the AIs hydramethylnon and imidacloprid, field strains did not display survivorship different than the lab strain, but >90% mortality was never achieved. Lastly, both field strains displayed resistance to indoxacarb, fipronil, acetamiprid, beta-cyfluthrin, bifenthrin, and lambda-cyhalothrin, but at varying levels. These results satisfy two objectives. First, baseline monitoring DCs were established for 14 insecticides presently registered for use against cockroaches, which represents a useful resource. Second, our findings reveal insecticide AIs with lowest resistance levels for use in forthcoming field studies that will investigate impacts of different insecticide deployment strategies on resistance management and evolution in cockroach field populations.
Asunto(s)
Blattellidae/efectos de los fármacos , Control de Insectos/métodos , Resistencia a los Insecticidas , Insecticidas/farmacología , Animales , Vivienda PopularRESUMEN
Insecticide resistance is a major impediment for effective control of Cimex lectularius L. Previous resistance detection studies with bed bugs have focused on certain pyrethroid, neonicotinoid, organochlorine, organophosphate, and carbamate insecticides. Within the pyrethroid class, resistance studies have mostly been limited to deltamethrin, lambda-cyhalothrin, and alpha- and beta-cyfluthrin. The goal of this study was to develop diagnostic concentration bioassays for assessing bed bug susceptibility levels to chlorfenapyr- and bifenthrin-containing products. First, glass vial and filter paper bioassay methods were compared for their utility in susceptibility monitoring. Statistical comparison of toxicity data between bioassays indicated that the vial assay was less confounded by assay susbtrate effects, required less insecticide, and was faster, especially for chlorfenapyr. Next, using vial diagnostic concentrations (LC99) for each insecticide, 10 laboratory-adapted field strains and the Harlan lab-susceptible strain were screened for susceptibility to chlorfenapyr and bifenthrin. The results of this study reveal recent bed bug susceptibility levels to certain chlorfenapyr- and bifenthrin-containing products. Reduced susceptibility was detected in three and five field strains to chlorfenapyr and bifenthrin, respectively. Detection of reduced susceptibility suggests that certain strains may be segregating toward greater chlorfenapyr and bifenthrin resistance. These results merit continuous resistance monitoring efforts to detect chlorfenapyr and bifenthrin susceptibility shifts. Additionally, to reduce insecticide selection pressures and delay resistance development, adoption of integrated bed bug control strategies that combine chemical and nonchemical methods is recommended.