Made available in DSpace on 2014-06-11T19:35:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-08-23Bitstream added on 2014-06-13T21:07:59Z : No. of bitstreams: 1 pereira_am_dr_rcla.pdf: 830341 bytes, checksum: de8af8468e88b6f5c5cf902007f24ed7 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / As abelhas Apis mellifera são insetos ecologicamente e economicamente importantes. Elas asseguram a polinização de diversas plantas contribuindo para a manutenção da biodiversidade. Seu valor econômico resulta não somente de seus produtos diretos mas também pela ativa polinização que exercem em culturas. A polinização feita por animais é importante para a reprodução sexuada de muitas culturas e para a maioria das plantas nativas, as quais também podem ser importantes como fonte de calorias e micronutrientes para os seres humanos. Além do mais, o declínio no número de polinizadores pode acarretar uma redução concomitante no número de espécies vegetais. A abelha A. mellifera, destaca-se como polinizador economicamente mais valioso para culturas em todo o mundo. Por outro lado, a agricultura moderna cada vez mais depende do uso de produtos químicos para controlar plantas daninhas, fungos e insetos-praga para assegurar a produtividade. Abelhas melíferas podem entrar em contato com tais agentes químicos devido suas atividades de coleta de água, resinas vegetais, pólen e néctar. A intoxicação resultante desta exposição pode ser letal, o que é facilmente identificável, ou causar efeitos na fisiologia e no comportamento do inseto. Tais efeitos, ocasionados por doses subletais, são difíceis de serem mensurados, como paralisia, desorientação ou mudanças comportamentais; porém, podem comprometer toda a estrutura social da colônia. Visando um melhor conhecimento dos efeitos de doses subletais de inseticidas em abelhas, estudou-se a ação dos ingredientes ativos Acetamiprido, Tiametoxam e Fipronil na sobrevivência e nos comportamentos de reflexo de extensão da probóscide e da atividade locomotora em operárias de A. mellifera. Preliminarmente, observou-se a DL50 vinte e quatro horas após o tratamento tópico do Acetamiprido Tiametoxam e Fipronil foram registrados... / the pollination of many wild flowers, and thus contributing to plant biodiversity. Their economic value derives not only from their direct products but also from their pollinating activity in crop plants. Animal pollination is important to sexual reproduction of many crops and the majority of wild plants, which can also be important for providing calories and micronutrients for humans. Furthermore, the decline of pollinating species can lead to a parallel decline in number of plant species. A. mellifera stands out as the most economically valuable crop pollinator in the world. Modern agriculture increasingly depends on the use of chemicals substances to control weeds, fungi and insect pests to ensure high yields. Honey bees may frequently become exposed to such chemicals as a consequence of their foraging activities collecting water, natural resins, pollen and nectar. Intoxication resulting from this exposure can be lethal, which is easily identifiable, or cause effects on the physiology and insect behavior. These effects, caused by sublethal doses are difficult to measure (such as paralysis, disorientation or behavioral changes), and can compromise the entire social structure of the colony. To improve the knowledge about the effects of insecticides sublethal doses effects in honey bees, we studied the action of the active ingredients Acetamiprid, Thiamethoxam and Fipronil on survival and behavior of the proboscis extension reflex (PER) and locomotor activity in workers of A. mellifera. Twenty-four hours after topic application, the LD50 values of Acetamiprid, Thiamethoxam and Fipronil were 9,3 μg/bee, 17 ng/bee and 1,9 ng/bee, respectively. We also estimated a LT50 with values of 1,4 hours, 3,8 hours and 19,8 hours to Acetamiprid, Thiamethoxam and Fipronil respectively. The behaviors were analyzed 1, 4 and 24 hours after topical application of active ingredients at doses corresponding... (Complete abstract click electronic access below)

abstract: This dissertation focused on the development and application of state-of-the-art monitoring tools and analysis methods for tracking the fate of trace level contaminants in the natural and built water environments, using fipronil as a model; fipronil and its primary degradates (known collectively as fiproles) are among a group of trace level emerging environmental contaminants that are extremely potent arthropodic neurotoxins. The work further aimed to fill in data gaps regarding the presence and fate of fipronil in engineered water systems, specifically in a wastewater treatment plant (WWTP), and in an engineered wetland. A review of manual and automated “active” water sampling technologies motivated the development of two new automated samplers capable of in situ biphasic extraction of water samples across the bulk water/sediment interface of surface water systems. Combined with an optimized method for the quantification of fiproles, the newly developed In Situ Sampler for Biphasic water monitoring (IS2B) was deployed along with conventional automated water samplers, to study the fate and occurrence of fiproles in engineered water environments; continuous sampling over two days and subsequent analysis yielded average total fiprole concentrations in wetland surface water (9.9 ± 4.6 to 18.1 ± 4.6 ng/L) and wetland sediment pore water (9.1 ± 3.0 to 12.6 ± 2.1 ng/L). A mass balance of the WWTP located immediately upstream demonstrated unattenuated breakthrough of total fiproles through the WWTP with 25 ± 3 % of fipronil conversion to degradates, and only limited removal of total fiproles in the wetland (47 ± 13%). Extrapolation of local emissions (5–7 g/d) suggests nationwide annual fiprole loadings from WWTPs to U.S. surface waters on the order of about one half to three quarters of a metric tonne. The qualitative and quantitative data collected in this work have regulatory implications, and the sampling tools and analysis strategies described in this thesis have broad applicability in the assessment of risks posed by trace level environmental contaminants. / Dissertation/Thesis / Doctoral Dissertation Civil and Environmental Engineering 2015

Made available in DSpace on 2016-06-02T19:23:02Z (GMT). No. of bitstreams: 1 6389.pdf: 1676206 bytes, checksum: 4f19f4ec15fdbd8ec8a9618ce747d102 (MD5) Previous issue date: 2014-09-03 / Financiadora de Estudos e Projetos / Fipronil (Fpn) is a phenyl-pyrazolic insecticide widely used for pest control in agriculture and livestock. It can be applied in very low doses as well as very high concentrations for the effective control of insects that show some resistance or tolerance to other families of insecticides. Fpn acts a blockers of chloride channels coupled to GABA and glutamate receptors, the latter are insect-specific targets not present in vertebrates. The aim of this study was to evaluate the possible effects on cardiac function of Hypostomus regani. of acute exposure (96 h) to sublethal concentrations (4.23 μ.Kg-1) of the pesticide Fpn, mixed into an artificial sediment. There was no difference in relative ventricular mass of the control group when compared to the group exposed to the Fpn. Ventricular strips from the Fpn exposed group exhibited showed higher twitch force (TF) and lower relationships between time-dependent variables and TF (time to peak tension - TPT/TF, and time to half relaxation - THR/TF) in response to increases in the frequency of stimulation or elevations of Ca2+ in physiological solution. Additionally, the exposed group maintained TF until a frequency of 2.6 Hz, while the TF of controls was only maintained until 2.0 Hz. Neither group showed potentiation of TF after non-physiological diastolic pause, indicating that the sarcoplasmic reticulum (RS) is not functional for contractility in this species. Corroborating that result, Western blots showed that SERCA2 was not expressed in either experimental group, these results indicate that the Ca2+ provided for ventricular contraction of H. regani is of extracellular origin. The replacement of NaCl with LiCl in saline caused negative inotropy in the exposed group, additionally, increments of Ca2+ caused positive inotropism in this group, indicating that the cardiotonic effect and greater contraction dynamics caused by exposure to Fpn were probably due to an increased expression and / or activity of NCX. Blocking of Na+/K+ pump led to a negative inotropism in both groups, presumably due to an overload of intracellular Ca2+. The cardiac pump capacity (CPC) of the exposed group was higher than the control group at all stimulation frequencies, probably due to increased activity and / or expression of NCX in the Fpn-exposed group. / O fipronil (Fpn) é um inseticida fenil-pirazólico amplamente utilizado para controle de pragas na agricultura e em animais domésticos. Pode ser aplicado desde doses muito baixas até muito altas para controle efetivo de insetos resistentes ou tolerantes a outras famílias de inseticidas. O Fpn atua como bloqueador dos canais de cloreto acoplados aos receptores GABA e aos receptores glutamatérgicos, estes últimos são alvo inseto-específico não presente nos vertebrados. O objetivo do presente estudo foi avaliar os possíveis efeitos da exposição aguda (96 h) em concentrações subletais (4,23μ.Kg-1) do pesticida Fpn, adicionado em sedimento artificial, sobre a função cardíaca in vitro do cascudo Hypostomus regani. Não foi encontrada diferença na massa ventricular relativa do grupo controle quando comparado ao grupo exposto ao Fpn. As preparações ventriculares do grupo exposto ao Fpn apresentaram maiores valores de força de contração (Fc) e menores valores das relações entre os parâmetros tempo-dependentes e a Fc (tempo para o pico de tensão TPT/Fc, e tempo para metade do relaxamento THR/fc) nos protocolos do tempo experimental, incrementos na frequência de estimulação e incrementos de Ca2+ na solução fisiológica. Adicionalmente, o grupo exposto manteve a Fc até a frequência 2,6 Hz, enquanto o grupo controle manteve até a frequência 2,0 Hz. Ambos os grupos não apresentaram potenciação da Fc após pausa diastólica não fisiológica, indicando que o retículo sarcoplasmático (RS) não é funcional para a contratilidade dessa espécie. Corroborando com esse resultado, a técnica de Western Blot revelou que a SERCA2 não foi expressa em ambos os grupos experimentais, tais resultados indicam que o Ca2+ para a contração do ventrículo de H. regani é proveniente do meio extracelular. A substituição do NaCl por LiCl na solução fisiológica causou um inotropismo negativo no grupo exposto, adicionalmente, os incrementos de Ca2+ provocaram um inotropismo positivo no grupo exposto, indicando que o efeito cardiotônico e a maior dinâmica de contração causados pela exposição ao Fpn é devido provavelmente a uma maior expressão e/ou atividade do NCX no grupo exposto. O bloqueio da bomba Na+/K+-ATPase provocou um inotropismo negativo em ambos os grupos, provavelmente devido a uma sobrecarga de Ca2+ intracelular. A capacidade de bombeamento cardíaco (CBC) do grupo exposto foi superior que o grupo exposto em todas as frequências de estimulação, devido a provável maior atividade e/ou expressão do NCX no grupo exposto.

Orientador: Carlos Alan Dias-Junior / Resumo: O fipronil é um inseticida fenilpirazol amplamente utilizado na Medicina Veterinária, na agricultura e domesticamente para o controle de pragas. O mecanismo responsável pela sua ação tóxica consiste na inibição seletiva dos receptores do ácido gama amino butírico GABA associado a canais de cloreto. Estudos recentes mostram que fipronil afeta organismos não-alvo, incluindo populações de espécies ambiental e, potencialmente, os seres humanos. O presente estudo verificou se a exposição a fipronil afeta a pressão arterial sistólica e biomarcadores relacionados. Assim, fipronil foi administrado oralmente a ratos (30 mg / kg / dia) durante 15 dias (grupo Fipronil) ou solução fisiológica (grupo controle). Fipronil aumentou significativamente a pressão arterial sistólica (158 ± 13 mmHg), em relação ao grupo controle (127 ± 3 mmHg). Significativamente, níveis mais elevados de fipronil no plasma foram observados no grupo Fipronil (0,46 ± 0.09μg / mL contra 0,17 ± 0.11μg / mL no grupo de controle). O grupo exposto ao Fipronil apresentou ganho de peso menor em comparação com o grupo controle. Enquanto o fipronil resultou num aumento das concentrações de endotelina-1, a redução da capacidade antioxidante e níveis menores de metaloproteinase de matriz 2 (MMP-2) e Nitrito/Nitrato em relação ao grupo controle, não foram observadas alterações em marcadores séricos renal e hepáticos. Portanto, este estudo sugere que o fipronil provoca hipertensão e a endotelina-1 desempenha um papel importante... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Recent reports show that fipronil affects non-target organisms, including environmental species populations and potentially humans. We aimed to examine if fipronil exposure affects the systolic blood pressure and related biomarkers. Thus, fipronil was orally administered to rats (30 mg/kg/day) during 15 days (Fipronil group) or physiological solution (Control group). While fipronil increased significantly the systolic blood pressure (158 ± 13 mmHg), no significant changes were observed in Control group (127 ± 3 mmHg). Significantly, higher levels of fipronil in plasma were observed in Fipronil group (0.46 ± 0.09 μg/mL versus 0.17 ± 0.11 μg/mL in Control group). Fipronil group showed lower weight gain compared with Control group. While fipronil resulted in higher concentrations of endothelin-1, reduced antioxidant capacity and lower levels of circulating matrix metalloproteinase 2 (MMP-2) and nitric oxide (NO) metabolites compared to Control group, no alteration was observed in serum biomarkers of renal and hepatic/biliary functional abilities. Therefore, this study suggests that fipronil causes hypertension and endothelin-1 plays a key role. Also, these findings suggest that reductions of both MMP-2 and NO may contribute with the elevation of systolic blood pressure observed with fipronil. / Mestre

Made available in DSpace on 2014-06-11T19:30:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-04-27Bitstream added on 2014-06-13T21:00:37Z : No. of bitstreams: 1 tofolo_vc_me_rcla.pdf: 520198 bytes, checksum: 81a305ec02da5170d24bfe930d1ea7be (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O objetivo deste trabalho foi procurar conhecer os efeitos de três substâncias químicas, sulfluramida, fipronil e clorpirifós, sobre a espécie de formiga não-alvo Ectatomma brunneum (Hymenoptera: Formicidae: Ectatomminae), respondendo às seguintes questões: as marcas comerciais de iscas formicidas granuladas utilizadas neste trabalho são atrativas a esta espécie de formiga não-alvo ou simplesmente repelentes? Sendo atrativas, qual o comportamento exercido pelas operárias? Elas ingerem as iscas no local ou carregam para o interior do ninho? Há devolução? Em condições de múltipla escolha alimentar, esta atratividade permanece ou ocorre somente na ausência do alimento convencional? No que acarreta o contato direto e indireto das formigas com as iscas? Ocorre mortalidade significativa? Qual dos ingredientes ativos é mais prejudicial? Os produtos são seletivos? Os resultados obtidos através dos testes em laboratório revelaram que, em condições normais de exposição, as operárias de E. brunneum não foram repelidas pelas iscas formicidas. No entanto, não houve atratividade suficiente para induzir o carregamento ou ingestão. Quando esse material foi umedecido, a atratividade aumentou significativamente, permitindo que porções das iscas fossem ingeridas na própria arena de forrageamento ou carregadas para o interior do ninho e distribuídas aos outros indivíduos, não sendo registrada, em nenhum dos tratamentos, a devolução total ou parcial das porções carregadas. Após 48 horas de exposição, os três ingredientes ativos foram tóxicos, de modo que a população foi reduzida em 35,56% no tratamento com clorpirifós, 31,11% com sulfluramida e 30% com fipronil ao final de 20 dias de observação. As iscas à base de fipronil foram mais atrativas que as de sulfluramida e clorpirifós... / This work aimed at contributing to a better knowledge on the effects of three chemical substances, sulfluramid, fipronil and chlorpyrifos, on the non-target species of ant Ectatomma brunneum (Hymenoptera: Formicidae: Ectatomminae), answering the following questions: are the brands of granulated insecticide baits employed in this work attractive to this species of non-target ant or are they just repellent? If attractive, what is the behavior exhibited by the workers? Do they ingest the baits in the spot or take them into the nest? Is there any devolution? Under conditions of multiple food choice, does this attractiveness remain or does it happen only in the lack of the conventional food? What is the outcome of direct or indirect contact between the ants and the baits? Is there significant mortality? Which of the active ingredients is the most harmful? Are the products selective? The results obtained from the tests in laboratory showed that, under conditions of normal exposure, the workers of E. brunneum were not repelled by the insecticide baits. Nevertheless, there was not enough attractiveness as to lead to transporting or ingesting. When the material was moistened, the attractiveness increased significantly, allowing portions of bait to be ingested at the very foraging arena or to be taken into the nest and distributed to the other individuals. Total or partial devolution of the portions carried was not observed in any of the treatments. After a 48 hour exposure the three active ingredients proved to be toxic, for the population was reduced in 35.56% in the treatment with chlorpyrifos, 31.11% with sulfluramid and 30% with fipronil at the end of 20 days of observation. The fipronil based baits were more attractive than the ones based on sulfluramid and chlorpyrifos...(Complete abstract click electronic access below)

<p>The German cockroach (<em>Blattella germanica</em>) is one of the most critical urban pests globally due to the health risks, such as asthma, it imposes on people. Insecticides are known to manage their large population sizes, but the rapid rate at which cockroaches develop resistance is a continuing problem. This 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 resistance profiles, so resistance profiles must be considered. This thesis addressed this little-studied issue in a controlled laboratory setting. Cockroach strains from Indianapolis, Indiana, Danville, Illinois, and Baltimore, Maryland, were used. Fifteen insecticide active ingredients most used by consumers and PMPs were selected for testing in vial bioassays to establish resistance profiles. 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. Selected population growth characteristics were compared in virgin females and nymphs in each cockroach strain to determine if certain population traits were associated with insecticide resistance. The results indicate that emamectin benzoate is the most effective active ingredient in causing the highest mortality in all strains in vial bioassays. No choice assays confirmed vial assay results the best, with Optigard (emamectin benzoate) being the most effective bait in all strains. The time a female carries its egg case and takes for a nymph to become an adult was significantly different across all strains, suggesting possible fitness costs for higher-level multi-resistance. The results acquired from these studies can help develop rapid tests to use in the field based on the no choice feeding assay while also adding more information supporting current resistance and cross-resistance evolution theories.</p>

Doctor of Philosophy / Department of Entomology / Larry L. Buschman / C. Michael Smith / Several studies were conducted to develop soybean management options that could provide protection from the soybean stem borer, Dectes texanus LeConte. Selected soybean genotypes were screened for host plant resistance against D. texanus. Soybean plants were grown in a footprint that could be covered by a field cage. When beetles were flying in the fields they were collected and placed in the field cages to increase the insect feeding pressure on the test plants. A susceptible commercial soybean variety treated with the systemic insecticide fipronil was used as a positive antibiosis check. Both commercial soybean varieties and plant introductions (PIs) obtained from the USDA National Soybean Germplasm Collection in maturity groups (MG) VI to VIII were tested over a four-year period. Since the number of ovipositions per plant could not be controlled, the ratio of oviposition punctures (OP’s) per live larvae (OP/ Lv) was used as a novel index of potential plant antibiosis to D. texanus. Field evaluations identified PI165673 as a genotype with a very high OP/ Lv ratio - similar to that for the fipronil antibiosis control. PI165673 appears to be potential source of resistance to D. texanus. Factorial analysis indicated that soybean maturity group was not significant factor in the expression of resistance. The OP/ Lv ratio appears to be more sensitive means of identifying antibiosis than other more conventional damage indices. The use of field cages demonstrated consistent plant responses from year to year during the multi-year study. Greenhouse-grown soybean plants, including transgenic plants containing the Manduca sexta chitinase gene, were not morphologically appropriate for successful D. texanus oviposition because the greenhouse-grown plants were poorly developed and had not produced enough pith in petioles. Therefore the greenhouse results were inconclusive. Analysis of the vertical distribution of D. texanus oviposition on soybean plants revealed that D. texanus oviposition was most likely to occur on leaf petioles on the upper five nodes of the plant canopy. Histomorphological observations of plant petioles indicated that the proportion of the petiole perimeter occupied by vascular bundles might be related to D. texanus oviposition. Both foliar and seed applications of fipronil suppressed D. texanus larval damage on soybean plants. The efficacy of these treatments was sustained for long periods, even until adult beetles were present in early August. The effects of the fipronil seed-treatment and harvest date on grain yield were both significant while the interaction was not. A physiological yield loss of 8.2% and plant lodging losses of 2.9% were associated with D. texanus infestation.

Made available in DSpace on 2014-06-11T19:22:59Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-04-17Bitstream added on 2014-06-13T19:28:37Z : No. of bitstreams: 1 pedro_j_me_rcla.pdf: 1811815 bytes, checksum: a40e56f40ac516c9c22abb3f5a86c289 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Os agrotóxicos constituem uma importante estratégia da agricultura, para a obtenção de uma produtividade economicamente viável, pois são substâncias utilizadas no combate de organismos indesejáveis. Os inseticidas são agentes que têm ação de combater insetos, tanto na fase adulta como larval. O fipronil é um composto do grupo fenil-pirazol, toxicologicamente classificado como altamente tóxico, amplamente utilizado em campos agrícolas do estado de São Paulo, bem como nas residências, para combater insetos pragas. A ação deste inseticida se dá pela sua ligação ao canal de cloro, promovendo o bloqueio da ativação da condução dos estímulos nervosos, pelo ácido gama-aminobutírico (GABA), uma substância que controla o fluxo de íons cloro, através da membrana da célula nervosa. Em pequenas concentrações, apresenta uma eficiente ação nos organismos alvos. Esta característica também pode causar problemas ao meio ambiente, muitas vezes, longe até dos lugares onde foi aplicado. O fipronil, em temperaturas moderadas, é estável no ambiente por cerca de um ano. Estudos mostram que esse inseticida pode ser degradado em diversos metabólitos, que são ainda mais tóxicos que ele. Quanto a sua persistência no ambiente, o fipronil apresenta variações decorrentes da sua formulação, mas os seus metabólicos podem ser mais persistentes que o próprio inseticida. Resíduos de fipronil podem ser bioacumulado no tecido adiposo, indicando uma potencialidade de transferência via cadeia trófica. No presente trabalho, foram avaliadas as potencilidades tóxicas, citotóxicas, genotóxicas e mutagênicas do inseticida fipronil, por meio de bioensaios com Allium cepa, cujas sementes foram expostas à germinação em fipronil. / The pesticides are an important strategy for agriculture, to obtain productivity economically viable, because they are substances used to eliminate pest organisms. Insecticides are agents which have action to combat insects, in both the adult and larval stage. The fipronil is a group composed of phenyl-pyrazole, toxicologically classified as highly toxic, and it is widely used in agricultural fields in Sao Paulo State, as well as in homes, to combat insect pests. This insecticide acts through its connection to the channel chlorine, promoting blockade in the activation of the conduct of nervous stimuli, the gamma-aminobutyric acid (GABA), a substance that controls the flow of chloride ions through the cell membrane of nerve. In small concentrations, presents an efficient action in the organism targets. This feature can also cause problems to the environment, often far to the places where it is applied. In moderate temperatures, the fipronil is stable in the environment for about a year. Studies show that this insecticide can be degraded in various metabolites, which are even more toxic than the fipronil. Relative to its persistence in the environment, the fipronil presents variations resulting from its formula, but their metabolites may be more persistent than the insecticide. Residues of fipronil can be bioacumulated in adipose tissue, indicating a potential of transference by the food chain. In the present research, it had been evaluated the toxic, cytotoxic, genotoxic and mutagenic potentials of the fipronil insecticide through bioassays with Allium cepa, whose seeds were exposed to germination in this insecticide. The results indicate that the insecticide presented no toxic and cytotoxic effects for the A. cepa species, when we compared the data resulting from the tests performed with the insecticide and with the negative control.

Les récepteurs ionotropes du GABA (GABARs) sont inhibés par des insecticides tels que les phénylpyrazoles (fipronil). Deux facteurs susceptibles de modifier leur sensibilité au fipronil ont été examinés : 1) l'édition de l'ARNm d'une sous-unité de GABAR (RDL) et 2) la phosphorylation par la PKC. La sous-unité RDL de drosophile présente des mutations (A301êS/G et/ou T350êM) induisant une résistance aux insecticides, ainsi que des sites d'édition dont un dans le domaine N-terminal (R122êG). Les effets fonctionnels de l'édition R122êG ont été testés par expression de divers isoformes de la sous-unité RDL (mutés ou non, édités ou non) dans des ovocytes de xénope. Les résultats montrent que l'édition R122êG entraîne une réduction de la sensibilité des récepteurs RDL au GABA et au fipronil. Deux types de récepteurs (GABAR1 et GABAR2) sont exprimés à la surface des neurones DUM isolés de Periplaneta americana, les GABAR2 étant régulés positivement par la CaMKII. Ce modèle cellulaire a été utilisé pour étudier, par la technique du patch-clamp, la régulation des GABARs par la PKC et ses conséquences sur les effets du fipronil. Les GABAR2 apparaissent plus sensibles à l'inhibition par des PKC que les GABAR1, et la potentialisation de l'activité des GABAR2 par la CaMKII s'exerce via l'inhibition d'une PKC. Les GABAR2 étant plus sensibles au fipronil que les GABAR1, leur blocage sélectif par une PKC entraîne une réduction importante de l'inhibition exercée par le fipronil. Le clonage de la sous-unité RDL dans la chaîne nerveuse de la blatte et dans les neurones DUM révèle la présence de sites potentiels de phosphorylation par la PKC et la CaMKII ainsi que l'existence de deux variants différant par vingt résidus dans la boucle M3-M4.