Publications by authors named "Edmund J Norris"

Background: This study investigated the behavioral responses and toxicity of three basic amines: 1-methylpiperazine, 1-methylpyrrolidine, and triethylamine (TEA), compounds suggested previously to be anosmic in vapor exposures to caged mosquitoes.

Results: These compounds showed repellency of Aedes aegypti mosquitoes, followed by flightlessness, knockdown, and paralysis, all increasing with exposure time and dosage. Electrophysiological experiments showed a blocking effect on nerve discharge of the Drosophila melanogaster larval central nervous system (CNS) with little evidence of hyperexcitation.

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Article Synopsis
  • The house fly poses significant challenges in agriculture and human health, particularly due to pesticide resistance.
  • Researchers evaluated 17 essential oil components (EOCs) for their toxicity and repellency against both resistant and susceptible strains of house flies, identifying thymol, (+)-pulegone, eugenol, and carvacrol as the most toxic.
  • The study suggests that some EOCs showed little resistance, while others had varying repellent effects, paving the way for future research on biopesticides for effective house fly management.
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Background: The Lone Star tick, Amblyomma americanum is important to human health because of a variety of pathogenic organisms transmitted to humans during feeding events, which underscores the need to identify novel approaches to prevent tick bites. Thus, the goal of this study was to test natural and synthetic molecules for repellent activity against ticks in spatial, contact and human fingertip bioassays.

Methods: The efficacy of essential oils and naturally derived compounds as repellents to Am.

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House flies are notoriously difficult to control, owing to their tendency to live in close relationships with humans and their livestock, and their rapid development of resistance to chemical controls. With this in mind, we explored an alternative chemical control, a spatial repellent to deter L. from points we wanted to protect (i.

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Chemical screening efforts recently found that 3-phenoxybenzaldehyde, a breakdown product of alpha-cyano pyrethroids, was a potent spatial repellent against mosquitoes in a glass tube repellency assay. In order to characterize this molecule further and identify structure-activity relationships, a set of 12 benzaldehyde analogues were screened for their repellency and toxicity in vapor phase exposures at 100 μg/cm. Dose-response analyses were performed for the most active compounds in order to better characterize their repellent potency and toxicity compared to those of other commercially available toxicants.

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Because of the increased interest in plant essential oils (PEO) for both home pest control and personal bite protection, the ability of fir needle (Abies balsamea) oil to synergize the 1-h knockdown and 24-h toxicity of 9 different synthetic insecticides was evaluated. Fir needle oil strongly synergized knockdown of the neonicotinoids, clothianidin, and thiamethoxam (between 16- and 24-fold), as well as natural pyrethrins (12-fold), but had less effect with organophosphates and fipronil. For 24-h mortality, only pirimiphos-methyl was strongly synergized by fir needle oil pretreatment (18-fold).

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The emergence of pyrethroid-resistant mosquitoes is a worldwide problem that necessitates further research into the development of new repellents and insecticides. This study explored the modification of existing pyrethroid acids to identify structural motifs that might not be affected by active site mutations that elicit pyrethroid resistance. Because synthetic pyrethroids almost always contain activity-dependent chiral centers, we chose to focus our efforts on exploring alkoxy moieties of esters obtained with 1--permethrinic and related acids, which we showed in previous studies to have repellent and/or repellent synergistic properties.

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As resistance to the limited number of insecticides available for medical and veterinary pests becomes more widespread, there is an urgent need for new insecticides and synergists on the market. To address this need, we conducted a study to assess the toxicity of three monoterpenoids-carvone, menthone, and fenchone-in comparison to permethrin and methomyl against adults of two common pests: the yellow fever mosquito () and the house fly (). We also examined the potential for these monoterpenoids to enhance the effectiveness of permethrin and methomyl when used together.

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We explored the potential of two sodium channel activators, veratrine and aconitine, as both insecticides and synergists of natural pyrethrins (NP) on Aedes aegypti adults and larvae. Aconitine was more toxic than veratrine, with an LD of 157 ng/mg compared to 376 ng/mg, on the pyrethroid-susceptible Orlando strain, but only aconitine showed significant resistance in the pyrethroid-resistant Puerto Rico strain (RR = 14.6 in topical application and 8.

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Nootkatone, a sesquiterpenoid isolated from Alaskan yellow cedar (Cupressus nootkatensis), is known to possess insect repellent and acaricidal properties and has recently been registered for commercial use by the Environmental Protection Agency. Previous studies failed to elucidate the mechanism of action of nootkatone, but we found a molecular overlay of picrotoxinin and nootkatone indicated a high degree of structural and electrostatic similarity. We therefore tested the hypothesis that nootkatone was a GABA-gated chloride channel antagonist, similar to picrotoxinin.

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It is important to identify repellents that can provide reliable protection from arthropod biting and prevent arthropod-borne diseases, such as malaria. In the present study, the spatial repellent activity and toxicity of two novel pyridinyl amides ( and ) were evaluated against , , and . In vapor repellency bioassays, compound was generally more effective than DEET and 2-undecanone, while compound was about as active as these standards.

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Background: The CDC Bottle Bioassay serves as an inexpensive and effective way to screen field-caught mosquitoes against a wide variety of insecticidal active ingredients and commercial formulations, with the goal of detecting resistant individuals. For this study, we assessed how sucrose-water (10% w/v) feeding status impacted the response of Aedes aegypti mosquitoes to select insecticides.

Results: Starvation for 24 or 48 h decreased permethrin and malathion mean survival time by about 40%, with little difference in the two starvation times.

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Resistance to currently utilized chemical insecticidal agents represents a significant threat to public health and food security worldwide. Better understanding the neurophysiological effects of available and candidate insecticidal molecules is valuable for characterizing the mechanisms of insecticide resistance, as well as the design and study of novel control chemistries. In this paper, we describe a method of recording nerve firing from the central nervous system of Aedes aegypti fourth instar larvae.

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With insecticide-resistant mosquito populations becoming an ever-growing concern, new vector control technologies are needed. With the lack of new chemical classes of insecticides to control mosquito populations, the development of novel synergists may improve the performance of available insecticides. We screened a set of 20 plant essential oils alone and in combination with natural pyrethrins against (Orlando) female adult mosquitoes to assess their ability to synergize this natural insecticide.

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A total of 115 aryl amides were synthesized and screened for vapor repellency against the Orlando (OR) strain of mosquitoes. Of these compounds, 29 had 1 h repellency EC values comparable to or better than ,-diethyl--toluamide (DEET, 1 h EC value of 35 μg/cm), with 2,2,3,3,3-pentafluoro--(4-fluorophenyl)propenamide () and 2,2,3,3,4,4,4-heptafluoro--(3,4,5-trifluorophenyl)butanamide () exhibiting the most potent EC values of 4.5 and 2.

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Article Synopsis
  • The study focuses on developing lightweight and strong insect-repellent fabrics to help combat viral diseases.
  • Permethrin was incorporated into polyamide fabrics using electrospinning and dip coating, with pre-formation addition proving most effective for fiber application.
  • Results showed that permethrin-treated fabrics had great insect repellent properties, especially electrospun nylon 6, which maintained durability against washing and light exposure.
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New insecticides are urgently needed for the control of arthropod vectors of public health diseases. As resistance to many insecticides used for the control of public health pests is ubiquitous, all available chemistries should be evaluated for their potential to effectively control both insecticide-susceptible and insecticide-resistant strains of mosquitoes. This study aimed to evaluate p-p'-difluoro-diphenyl-trichloroethane (DFDT) as a mosquito control technology and relate its activity to that of DDT.

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Insecticide resistance poses a significant threat to the control of arthropods that transmit disease agents. Nanoparticle carriers offer exciting opportunities to expand the armamentarium of insecticides available for public health and other pests. Most chemical insecticides are delivered by contact or feeding, and from there must penetrate various biological membranes to reach target organs and kill the pest organism.

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Background: The compound 2-((4-ethyl-5-(pyridin-3-yl)-4H-1,2,4-triazol-3-yl)thio)-N-(4-ethylphenyl) acetamide (VUAA1) is reported to be an odorant receptor co-receptor (Orco) agonist in insects with potential use as an insect repellent. For this study, the biological activity of VUAA1 was investigated in several bioassays with Aedes aegypti, including adult contact, spatial repellency, and larval repellency assays, as well as topical, injection, and feeding toxicity assays. Neurophysiological action was further explored by analysis of fruit fly central nervous system firing, cockroach axon recordings, patch clamp analysis of Kv2 potassium channel, and acetylcholinesterase inhibition studies.

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Background: The western corn rootworm is an economically important pest of corn. Management tactics include pyrethroid and organophosphate insecticides, which may be applied as a mixture to protect corn roots. The goal of our study was to characterize the effects of pyrethroids and organophosphates alone and in combination on larval corn rootworm mortality and injury to corn roots.

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Pyrethroids are one of the most commonly used classes of insecticides, and their acid and alcohol components are esterase degradation products, usually considered to be biologically inactive. In this study, it was found that several pyrethroid acids had a spatial repellent activity that was greater than DEET, often more active than the parent pyrethroids, and showed little cross resistance in a pyrethroid-resistant Puerto Rico strain of mosquitoes. Further investigation revealed that the acids can synergize not only contact repellent standards but also other pyrethroid components as well as the parent pyrethroids themselves.

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Many synthetic insecticides cause immobilization in insect pests after they are exposed. This immobilization or knockdown is an important feature of intoxication that contributes to the abatement of pest insect populations, while preventing vectors of disease from biting and spreading pathogenic organisms to susceptible individuals. We have previously demonstrated that certain plant essential oils rapidly immobilize adult female mosquitoes that have been exposed via topical application.

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Background: The mosquito, Aedes aegypti (Diptera: Culicidae), is a vector of dengue fever, zika, chikungunya, and yellow fever viruses, and in many areas possesses significant levels of resistance to pyrethroids. Behavioral performance was assessed in 15, 30, and 60 min exposures in a high throughput vapor phase spatial repellency assay to three contact repellent standards: N,N-diethyl-3-methylbenzamide (DEET), ethyl 3-[acetyl(butyl)amino] propanoate (IR3535), and 2-undecanone, as well as pyrethrum extract, transfluthrin, and metofluthrin in susceptible (Orlando) and a pyrethroid-resistant Puerto Rico strain of Aedes aegypti. Additionally, electroantennographic studies were used to investigate the antennal sensitivities to these compounds in both strains.

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Article Synopsis
  • Mosquito-borne diseases kill around 700,000 people each year and worsen in areas lacking effective control measures and resources.
  • Research shows that combining plant essential oils with insecticides like permethrin and deltamethrin significantly increases their effectiveness, particularly against mosquito strains resistant to pyrethroids.
  • The study indicates that plant essential oils may inhibit detoxification enzymes in mosquitoes, enhancing the potency of traditional insecticides and suggesting their potential as valuable additives in pest control strategies.
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Every year, approximately 700,000 people die from complications associated with etiologic disease agents transmitted by mosquitoes. While insecticide-based vector control strategies are important for the management of mosquito-borne diseases, insecticide-resistance and other logistical hurdles may lower the efficacy of this approach, especially in developing countries. Repellent technologies represent another fundamental aspect of preventing mosquito-borne disease transmission.

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