The Experts below are selected from a list of 2619 Experts worldwide ranked by ideXlab platform
Anastasia Tsagkarakou - One of the best experts on this subject based on the ideXlab platform.
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insecticide resistance in bemisia tabaci homoptera aleyrodidae populations from crete
Pest Management Science, 2005Co-Authors: Emmanouil Roditakis, Nikos E. Roditakis, Anastasia TsagkarakouAbstract:The resistance levels to α-cypermethrin, Bifenthrin, pirimiphos-methyl, endosulfan and imidacloprid were determined in Bemisia tabaci (Gennadius) from Crete. Five B tabaci populations collected from greenhouse and outdoor crops were bioassayed and compared with a reference susceptible strain. Bemisia tabaci collected in a floriculture greenhouse exhibited the highest resistance against all insecticides: at LC50, resistance factors were 23-fold for Bifenthrin, 80-fold for α-cypermethrin, 18-fold for pirimiphos-methyl, 58-fold for endosulfan and 730-fold for imidacloprid. A population collected on outdoor melons was more susceptible than the reference strain against all insecticides tested, suggesting the occurrence of local highly susceptible B tabaci populations in 'refugia'. In pairwise comparisons of resistance levels, correlation was observed between the LC50 values of the pyrethroid insecticides Bifenthrin and α-cypermethrin. 2005 Society of Chemical Industry
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insecticide resistance in bemisia tabaci homoptera aleyrodidae populations from crete
Pest Management Science, 2005Co-Authors: Emmanouil Roditakis, Nikos E. Roditakis, Anastasia TsagkarakouAbstract:The resistance levels to alpha-cypermethrin, Bifenthrin, pirimiphos-methyl, endosulfan and imidacloprid were determined in Bemisia tabaci (Gennadius) from Crete. Five B tabaci populations collected from greenhouse and outdoor crops were bioassayed and compared with a reference susceptible strain. Bemisia tabaci collected in a floriculture greenhouse exhibited the highest resistance against all insecticides: at LC50, resistance factors were 23-fold for Bifenthrin, 80-fold for alpha-cypermethrin, 18-fold for pirimiphos-methyl, 58-fold for endosulfan and 730-fold for imidacloprid. A population collected on outdoor melons was more susceptible than the reference strain against all insecticides tested, suggesting the occurrence of local highly susceptible B tabaci populations in 'refugia'. In pairwise comparisons of resistance levels, correlation was observed between the LC50 values of the pyrethroid insecticides Bifenthrin and alpha-cypermethrin.
Chow Yang Lee - One of the best experts on this subject based on the ideXlab platform.
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Surface contact toxicity and synergism of several insecticides against different stages of the tropical bed bug, Cimex hemipterus (Hemiptera: Cimicidae)
Pest management science, 2011Co-Authors: Yee Fatt How, Chow Yang LeeAbstract:BACKGROUND: Five formulated insecticides (lambda-cyhalothrin at 10 mg m−2, Bifenthrin at 50 mg m−2, fipronil at 10 mg m−2, fenitrothion at 50 mg m−2, imidacloprid at 5 mg m−2) and one active ingredient (DDT at 500 mg m−2) were evaluated using a surface contact method against early and late instars and adults of two strains of the tropical bed bug, Cimex hemipterus (F.). Synergism of lambda-cyhalothrin and fipronil using piperonyl butoxide (PBO) was also assessed. RESULTS: The order of susceptibility of different stages of bed bugs was as follows: early stage − lambda-cyhalothrin > Bifenthrin = imidacloprid > fipronil > fenitrothion > DDT; late stage—lambda-cyhalothrin > Bifenthrin > fenitrothion > imidacloprid > fipronil > DDT; adult—lambda-cyhalothrin > imidacloprid > Bifenthrin > fenitrothion > fipronil > DDT. The late instars exhibited significantly higher LT50 among the life stages. The addition of PBO to fipronil increased the susceptibility of the insects. CONCLUSIONS: Lambda-cyhalothrin, Bifenthrin, fenitrothion and fipronil at the recommended application rates were effective against C. hemipterus. Although imidacloprid demonstrated good initial response against C. hemipterus, the insects showed substantial recovery 72 h post-treatment. The late instars (fourth and fifth instars) should be used as the model for toxicological evaluation. Copyright © 2011 Society of Chemical Industry
James M Starr - One of the best experts on this subject based on the ideXlab platform.
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tissue time course and bioavailability of the pyrethroid insecticide Bifenthrin in the long evans rat
Xenobiotica, 2016Co-Authors: Michael F Hughes, David G Ross, Brenda C Edwards, Michael J Devito, James M StarrAbstract:Abstract1. Pyrethroids are neurotoxic and parent pyrethroid appears to be toxic entity. This study evaluated the oral disposition and bioavailability of Bifenthrin in the adult male Long-Evans rat.2. In the disposition study, rats were administered Bifenthrin (0.3 or 3 mg/kg) by oral gavage and serially sacrificed (0.25 h to 21 days). Blood, liver, brain and adipose tissue were removed. In the bioavailability study, blood was collected serially from jugular vein cannulated rats (0.25 to 24 h) following oral (0.3 or 3 mg/kg) or intravenous (0.3 mg/kg) administration of Bifenthrin. Tissues were extracted and analyzed for Bifenthrin by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS).3. Bifenthrin concentration in blood and liver peaked 1–2-h postoral administration and were approximately 90 ng/ml (or g) and 1000 ng/ml (or g) for both tissues at 0.3 and 3 mg/kg, respectively. Bifenthrin was rapidly cleared from both blood and liver. Brain concentrations peaked at 4–6 h and were lo...
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tissue time course and bioavailability of the pyrethroid insecticide Bifenthrin in the long evans rat
Xenobiotica, 2016Co-Authors: Michael F Hughes, David G Ross, Brenda C Edwards, Michael J Devito, James M StarrAbstract:1. Pyrethroids are neurotoxic and parent pyrethroid appears to be toxic entity. This study evaluated the oral disposition and bioavailability of Bifenthrin in the adult male Long-Evans rat. 2. In the disposition study, rats were administered Bifenthrin (0.3 or 3 mg/kg) by oral gavage and serially sacrificed (0.25 h to 21 days). Blood, liver, brain and adipose tissue were removed. In the bioavailability study, blood was collected serially from jugular vein cannulated rats (0.25 to 24 h) following oral (0.3 or 3 mg/kg) or intravenous (0.3 mg/kg) administration of Bifenthrin. Tissues were extracted and analyzed for Bifenthrin by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). 3. Bifenthrin concentration in blood and liver peaked 1-2-h postoral administration and were approximately 90 ng/ml (or g) and 1000 ng/ml (or g) for both tissues at 0.3 and 3 mg/kg, respectively. Bifenthrin was rapidly cleared from both blood and liver. Brain concentrations peaked at 4-6 h and were lower than in blood at both doses (12 and 143 ng/g). Bifenthrin in adipose tissue peaked at the collected time points of 8 (157 ng/g) and 24 (1145 ng/g) h for the 0.3 and 3 mg/kg doses, respectively and was retained 21 days postoral administration. Following intravenous administration, the blood Bifenthrin concentration decreased bi-exponentially, with a distribution half-life of 0.2 h and an elimination half-life of 8 h. Bifenthrin bioavailability was approximately 30%. These disposition and kinetic Bifenthrin data may decrease uncertainties in the risk assessment for this pyrethroid insecticide.
Richard E Connon - One of the best experts on this subject based on the ideXlab platform.
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Pyrethroid bioaccumulation in field-collected insecticide-resistant Hyalella azteca
Ecotoxicology, 2021Co-Authors: Kara E. Huff Hartz, Richard E Connon, Donald P Weston, Nadhirah Johanif, Michael J. LydyAbstract:Wild-type Hyalella azteca are highly sensitive to pyrethroid insecticides and typically do not survive exposure; however, pyrethroid bioaccumulation by insecticide-resistant H. azteca is an important potential risk factor for the transfer of pyrethroids to higher trophic species in aquatic systems. In the current study, four populations of pyrethroid-resistant H. azteca with corresponding sediment samples were sampled throughout the year, and nine-current use pyrethroids (tefluthrin, fenpropathrin, Bifenthrin, cyhalothrin, permethrin, cyfluthrin, cypermethrin, esfenvalerate and deltamethrin) were measured. Bifenthrin was detected in every pyrethroid-resistant H. azteca tissue sample, up to 813 ng/g lipid, while cyhalothrin and permethrin were detected in fewer (18 and 28%, respectively) samples. Concurrent sampling of the sediment showed total pyrethroid concentrations exceeding toxic unit thresholds for non-resistant H. azteca survival, and confirmed the ubiquitous presence of Bifenthrin at each site and sampling event. Bifenthrin concentrations in H. azteca tended to be higher in samples collected in winter months, and seasonal factors, such as temperature and rainfall, may have contributed to the noted differences in bioaccumulation. Finally, the Bifenthrin and permethrin biota-sediment accumulation factors (BSAF) for pyrethroid-resistant H. azteca were similar to the BSAF values for less sensitive invertebrates, and therefore the development of resistance may enable an additional pathway for trophic transfer of pyrethroids in species that would otherwise be too sensitive to survive the exposure.
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environmentally relevant concentrations of Bifenthrin affect the expression of estrogen and glucocorticoid receptors in brains of female western mosquitofish
Aquatic Toxicology, 2019Co-Authors: Richard E Connon, Isaac Y Ligocki, Amelia Munson, Victoria Farrar, Rechelle Viernes, Rebecca M CalisiAbstract:Abstract In recent decades, pyrethroid pesticides have been deemed a safer alternative to previously used pesticides. While some evidence supports this assumption in mammals and birds, exposure to certain pyrethroids can affect concentrations of hormones vital to reproduction in fish. Thus, we hypothesized that pyrethroid exposure impacts fish reproductive behavior and the expression of genes associated with reproduction. We tested our hypothesis by examining effects of the widely used pyrethroid pesticide, Bifenthrin, on the reproductive behaviors of the broadly distributed livebearing western mosquitofish, Gambusia affinis. We exposed sexually mature female fish to one of five environmentally relevant concentrations of Bifenthrin and conducted behavioral assays to assess reproductive, social, and space use behaviors before and after exposure. We did not detect changes in behaviors measured in response to Bifenthrin. However, exposure was associated with increased expression of an estrogen receptor gene (ER-α) and glucocorticoid receptor (GR) in brain tissue at Bifenthrin concentrations at concentrations of 5.90 and 24.82 ng/L, and 5.90 and 12.21 ng/L, respectively. Our study supports the perspective that the use of multiple endpoints through integrative approaches is essential for understanding the cumulative impact of pollutants. Integrating physiological, morphological, and behavioral investigations of nonlethal concentrations of pollutants like Bifenthrin may heighten our potential to predict their impact on individuals, populations, and communities.
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developmental exposure to environmentally relevant concentrations of Bifenthrin alters transcription of mtor and ryanodine receptor dependent signaling molecules and impairs predator avoidance behavior across early life stages in inland silversides m
Aquatic Toxicology, 2019Co-Authors: Susanne M Brander, Simone Hasenbein, Daniel F Frank, Danielle J Harvey, Pamela J Lein, Juergen Geist, Richard E ConnonAbstract:Altered transcription of calcium-dependent signaling cascades involving the ryanodine receptor (RyR) and mechanistic target of rapamycin (mTOR) in response to environmental exposures have been described in model vertebrates, including zebrafish, while the relevance for wild fishes remains unknown. To address this knowledge gap, we exposed the euryhaline model species Menidia beryllina (inland silversides) to the insecticide Bifenthrin, a known modulator of calcium signaling. The main objectives of this study were to determine: (1) whether exposure of developing silversides to environmentally relevant concentrations of Bifenthrin alters their behavior; and (2) whether behavioral changes correlate with altered expression of genes involved in RyR and mTOR-dependent signaling pathways. At six hours post fertilization (hpf), inland silversides were exposed to Bifenthrin at 3, 27 and 122 ng/L until 7 days post fertilization (dpf, larvae hatched at 6dpf), followed by a 14-day recovery period in uncontaminated water. Transcriptional responses were measured at 5, 7 and 21 dpf; locomotor behavior following external stimuli and response to an olfactory predator cue were assessed at 7 and 21 dpf. Bifenthrin elicited significant non-monotonic transcriptional responses in the majority of genes examined at 5 dpf and at 21 dpf. Bifenthrin also significantly altered predator avoidance behavior via olfactory mechanisms with main effects identified for animals exposed to 3 and 27 ng/L. Behavioral effects were not detected in response to visual stimuli during acute exposure, but were significant in the predator-cue assessment following the recovery period, suggesting delayed and long-term effects of early developmental exposures to Bifenthrin. Our findings demonstrate that at picomolar (pM) concentrations, which are often not represented in ecotoxicological studies, Bifenthrin perturbs early development of inland silversides. These developmental impacts are manifested behaviorally at later life stages, specifically as altered patterns of predator avoidance behavior, which have been correlated with population decline. Collectively, these data suggest that Bifenthrin may be negatively impacting wild fish populations.
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transcriptomic changes underlie altered egg protein production and reduced fecundity in an estuarine model fish exposed to Bifenthrin
Aquatic Toxicology, 2016Co-Authors: Susanne M Brander, Ken M Jeffries, Bryan J Cole, Bethany M Decourten, Wilson J White, Simone Hasenbein, Nann A Fangue, Richard E ConnonAbstract:Pyrethroid pesticides are a class of insecticides found to have endocrine disrupting properties in vertebrates such as fishes and in human cell lines. Endocrine disrupting chemicals (EDCs) are environmental contaminants that mimic or alter the process of hormone signaling. In particular, EDCs that alter estrogen and androgen signaling pathways are of major concern for fishes because these EDCs may alter reproductive physiology, behavior, and ultimately sex ratio. Bifenthrin, a pyrethroid with escalating usage, is confirmed to disrupt estrogen signaling in several species of fish, including Menidia beryllina (inland silverside), an Atherinid recently established as a euryhaline model. Our main objective was to broadly assess the molecular and physiological responses of M. beryllina to the ng/L concentrations of Bifenthrin typically found in the environment, with a focus on endocrine-related effects, and to discern links between different tiers of the biological hierarchy. As such, we evaluated the response of juvenile Menidia to Bifenthrin using a Menidia-specific microarray, quantitative real-time polymerase chain reaction (qPCR) on specific endocrine-related genes of interest, and a Menidia-specific ELISA to the egg-coat protein choriogenin, to evaluate a multitude of molecular-level responses that would inform mechanisms of toxicity and any underlying causes of change at higher biological levels of organization. The sublethal nominal concentrations tested (0.5, 5 and 50ng/L) were chosen to represent the range of concentrations observed in the environment and to provide coverage of a variety of potential responses. We then employed a 21-day reproductive assay to evaluate reproductive responses to Bifenthrin (at 0.5ng/L) in a separate group of adult M. beryllina. The microarray analysis indicated that Bifenthrin influences a diverse suite of molecular pathways, from baseline metabolic processes to carcinogenesis. A more targeted examination of gene expression via qPCR demonstrated that Bifenthrin downregulates a number of estrogen-related transcripts, particularly at the lowest exposure level. Choriogenin protein also decreased with exposure to increasing concentrations of Bifenthrin, and adult M. beryllina exposed to 0.5ng/L had significantly reduced reproductive output (fertilized eggs per female). This reduction in fecundity is consistent with observed changes in endocrine-related gene expression and choriogenin production. Taken together, our results demonstrate that environmental concentrations of Bifenthrin have potential to interfere with metabolic processes, endocrine signaling, and to decrease reproductive output.
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effect assessment and regulation of pesticide mixtures in aquatic ecosystems
2014Co-Authors: Simone Hasenbein, Richard E Connon, Sharon P Lawler, Juergen GeistAbstract:Laboratory toxicity testing is the primary tool used for surface water environmental risk assessment, however there are critical information gaps regarding the sublethal effects of pesticides. Sublethal toxicity can negatively affect organism fitness, and often occurs at fractions of lethal effect concentrations. In this study, we compared the lethal and sublethal toxicities of four commonly used pesticides, Bifenthrin, permethrin, cyfluthrin, and chlorpyrifos, on two freshwater invertebrates, Chironomus dilutus and Hyalella azteca. We analyzed lethal toxicity over ten day (10d) exposures, and measured the sublethal toxicity on swimming motility and growth of surviving individuals at the end of each 10d test. H. azteca were between 4 and 100 times more sensitive than C. dilutus to the pesticides tested. Pyrethroids were more toxic than the organophosphate chlorpyrifos in both species, and Bifenthrin and cyfluthrin were the most potent. Growth was a good indicator of toxicity for C. dilutus with cyfluthrin being the most toxic, followed by permethrin, and Bifenthrin. Motility served as the best endpoint in assessing sublethal effects in both species. Decreased motility was detected at concentrations as low as 10% of the corresponding LC50 values; levels commonly detected in environmental water samples. Growth of H. azteca was significantly affected by Bifenthrin only. Invertebrates like C. dilutus and H. azteca are important components of the aquatic food web, and lethal and sublethal effects elicited by pesticide exposures have the potential to disrupt food webs and community structure in aquatic environments.
Blair D Siegfried - One of the best experts on this subject based on the ideXlab platform.
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cross resistance and synergism bioassays suggest multiple mechanisms of pyrethroid resistance in western corn rootworm populations
PLOS ONE, 2017Co-Authors: Adriano E Pereira, Dariane Souza, Sarah N Zukoff, Lance J Meinke, Blair D SiegfriedAbstract:Recently, resistance to the pyrethroid Bifenthrin was detected and confirmed in field populations of western corn rootworm, Diabrotica virgifera virgifera LeConte from southwestern areas of Nebraska and Kansas. As a first step to understand potential mechanisms of resistance, the objectives of this study were i) to assess adult mortality at diagnostic concentration-LC99 to the pyrethroids Bifenthrin and tefluthrin as well as DDT, ii) estimate adult and larval susceptibility to the same compounds as well as the organophosphate methyl-parathion, and iii) perform synergism experiments with piperonyl butoxide (PBO) (P450 inhibitor) and S,S,S-tributyl-phosphorotrithioate (DEF) (esterase inhibitor) in field populations. Most of the adult field populations exhibiting some level of Bifenthrin resistance exhibited significantly lower mortality to both pyrethroids and DDT than susceptible control populations at the estimated LC99 of susceptible populations. Results of adult dose-mortality bioassays also revealed elevated LC50 values for Bifenthrin resistant populations compared to the susceptible control population with resistance ratios ranging from 2.5 to 5.5-fold for Bifenthrin, 28 to 54.8-fold for tefluthrin, and 16.3 to 33.0 for DDT. These bioassay results collectively suggest some level of cross-resistance between the pyrethroids and DDT. In addition, both PBO and DEF reduced the resistance ratios for resistant populations although there was a higher reduction in susceptibility of adults exposed to PBO versus DEF. Susceptibility in larvae varied among insecticides and did not correlate with adult susceptibility to tefluthrin and DDT, as most resistance ratios were < 5-fold when compared to the susceptible population. These results suggest that both detoxifying enzymes and target site insensitivity might be involved as resistance mechanisms.
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evidence of field evolved resistance to Bifenthrin in western corn rootworm diabrotica virgifera virgifera leconte populations in western nebraska and kansas
PLOS ONE, 2015Co-Authors: Adriano E Pereira, Sarah N Zukoff, Lance J Meinke, Wade B French, Haichuan Wang, Blair D SiegfriedAbstract:Pyrethroid insecticides have been used to control larvae or adults of the western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, a key pest of field corn in the United States. In response to reports of reduced efficacy of pyrethroids in WCR management programs in southwestern areas of Nebraska and Kansas the present research was designed to establish a baseline of susceptibility to the pyrethroid insecticide, Bifenthrin, using susceptible laboratory populations and to compare this baseline with susceptibility of field populations. Concentration-response bioassays were performed to estimate the baseline susceptibility. From the baseline data, a diagnostic concentration (LC99) was determined and used to test adults of both laboratory and field populations. Larval susceptibility was also tested using both laboratory and field populations. Significant differences were recorded in adult and larval susceptibility among WCR field and laboratory populations. The highest LC50 for WCR adults was observed in populations from Keith 2 and Chase Counties, NE, with LC50s of 2.2 and 1.38 μg/vial, respectively, and Finney County 1, KS, with 1.43 μg/vial, as compared to a laboratory non-diapause population (0.24 μg/vial). For larvae, significant differences between WCR field and laboratory populations were also recorded. Significant differences in mortalities at the diagnostic Bifenthrin concentration (LC99) were observed among WCR adult populations with western Corn Belt populations exhibiting lower susceptibility to Bifenthrin, especially in southwestern Nebraska and southwestern Kansas. This study provides evidence that resistance to Bifenthrin is evolving in field populations that have been exposed for multiple years to pyrethroid insecticides. Implications to sustainable rootworm management are discussed.
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toxicity of insecticide bait mixtures to insecticide resistant and susceptible western corn rootworms coleoptera chrysomelidae
Crop Protection, 2003Co-Authors: Srinivas Parimi, Lance J Meinke, Timothy M Nowatzki, Laurence D Chandler, Wade B French, Blair D SiegfriedAbstract:Organophosphate resistant and susceptible populations of the western corn rootworm, Diabrotica virgifera virgifera LeConte. were subjected to adult feeding bioassays with different combinations of insecticide and a cucurbitacin bait. Five technical grade insecticides (methyl-parathion, carbaryl, fipronil, Bifenthrin and indoxacarb) were used in combination with Invite ECt as the feeding stimulant. Differences in susceptibility to the insecticide/bait combinations were observed among the resistant and susceptible populations for methyl-parathion and carbaryl. Susceptibility to fipronil, Bifenthrin and indoxacarb was similar among the resistant and susceptible populations. Assays in which response to the insecticide/bait combination was compared with the bait alone indicated that methyl-parathion and Bifenthrin were deterrent when compared to other treatments. These results suggest that the efficacy of Invite as a feeding stimulant in combination with certain insecticides may be compromised by previously identified resistance and by insecticides that antagonize the feeding stimulation of the cucurbitacin bait. r 2003 Elsevier Science Ltd. All rights reserved.