106 research outputs found

    Odorants for surveillance and control of the Asian Citrus Psyllid (Diaphorina citri).

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    BackgroundThe Asian Citrus Psyllid (ACP), Diaphorina citri, can transmit the bacterium Candidatus Liberibacter while feeding on citrus flush shoots. This bacterium causes Huanglongbing (HLB), a major disease of citrus cultivation worldwide necessitating the development of new tools for ACP surveillance and control. The olfactory system of ACP is sensitive to variety of odorants released by citrus plants and offers an opportunity to develop new attractants and repellents.ResultsIn this study, we performed single-unit electrophysiology to identify odorants that are strong activators, inhibitors, and prolonged activators of ACP odorant receptor neurons (ORNs). We identified a suite of odorants that activated the ORNs with high specificity and sensitivity, which may be useful in eliciting behavior such as attraction. In separate experiments, we also identified odorants that evoked prolonged ORN responses and antagonistic odorants able to suppress neuronal responses to activators, both of which can be useful in lowering attraction to hosts. In field trials, we tested the electrophysiologically identified activating odorants and identified a 3-odor blend that enhances trap catches by ∼230%.ConclusionThese findings provide a set of odorants that can be used to develop affordable and safe odor-based surveillance and masking strategies for this dangerous pest insect

    3.13 Tank mixtures of insecticides and fungicides, adjuvants, additives, fertilizers and their effects on honey bees after contact exposure in a spray chamber

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    In agriculture honey bees may be exposed to multiple pesticides. In contrast to single applications of plant protection products (PPP), the effects of tank mixtures of two or more PPP on honey bees are not routinely assessed in the risk assessment of plant protection products. However, tank mixes are often common practice by farmers. Mixtures of practically non-toxic substances can lead to synergistic increase of toxic effects on honey bees, observed for the first time in 19921 in combinations of pyrethroids and azole fungicides. 2004 Iwasa et al. already reported that ergosterol-biosynthesis-inhibiting (EBI) fungicides strongly increase the toxicity of neonicotinoids in laboratory for the contact exposure route. Furthermore, in agricultural practice additives, adjuvants and fertilizers may be added to the spray solution. For these additives usually no informations on potential side effects on bees are available when mixed with plant protection products. Therefore, it is considered necessary to investigate possible additive or synergistic impacts and evaluate potentially critical combinations to ensure protection of bees. Here, we investigated the effects on bees of combinations of insecticides, fungicides and fertilizers under controlled laboratory conditions. A spray chamber was used to evaluate effects following contact exposure by typical field application rates. Subsequently, mortality and behaviour of bees were monitored for at least 48 h following the OECD acute contact toxicity test 2143. Dependencies of synergistic effects and the time intervals between the applications of the mixing partners were evaluated.In agriculture honey bees may be exposed to multiple pesticides. In contrast to single applications of plant protection products (PPP), the effects of tank mixtures of two or more PPP on honey bees are not routinely assessed in the risk assessment of plant protection products. However, tank mixes are often common practice by farmers. Mixtures of practically non-toxic substances can lead to synergistic increase of toxic effects on honey bees, observed for the first time in 19921 in combinations of pyrethroids and azole fungicides. 2004 Iwasa et al. already reported that ergosterol-biosynthesis-inhibiting (EBI) fungicides strongly increase the toxicity of neonicotinoids in laboratory for the contact exposure route. Furthermore, in agricultural practice additives, adjuvants and fertilizers may be added to the spray solution. For these additives usually no informations on potential side effects on bees are available when mixed with plant protection products. Therefore, it is considered necessary to investigate possible additive or synergistic impacts and evaluate potentially critical combinations to ensure protection of bees. Here, we investigated the effects on bees of combinations of insecticides, fungicides and fertilizers under controlled laboratory conditions. A spray chamber was used to evaluate effects following contact exposure by typical field application rates. Subsequently, mortality and behaviour of bees were monitored for at least 48 h following the OECD acute contact toxicity test 2143. Dependencies of synergistic effects and the time intervals between the applications of the mixing partners were evaluated

    Polymers selection for a liquid inoculant of Azospirillum brasilense based on the Arrhenius thermodynamic model

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    Plant growth promoting bacteria (PGPB) enhances the growth of their hosts and can protect them from biotic and abiotic stresses. Bacterial inoculants contain one or more of these beneficial strains in a carrier material, which must be able to maintain the viability of the cells during the time of storage, and also guarantee the biological activity of the strains once applied in the soil. These inoculants can be solid, liquid, gel or oil-based, depending on the characteristics of the strains and the shelf life expected by the producers. In this study, we used a method of accelerated degradation to select a polymer and a concentration to maintain cell stability of a liquid inoculant based on the strain C16 Azospirillum brasilense. A screening at 45°C was made to compare the protectant effect of five polymers on the viability of the strain (p/v): carrageenan (1.5%), sodium alginate (1%), trehalose (10 mM), polyvinylpyrrolidone (2%), glycerol (10 mM) and phosphate saline buffer as control. Carrageenan and sodium alginate showed significant differences in cell viability over the use of other polymers (P < 0.05). We evaluated cell viability with these two polymers at three concentrations and three different temperatures (4, 28 and 45°C) for 60 days and determined the bacterial degradation rates. Based on the Arrhenius thermodynamic model, we calculated the time required to reduce cell concentration in three log units, and observed that the protectant activity of each polymer and each concentration depends on the temperature of storage. Cell viability was best preserved in all treatments at 4°C. In general, alginate prolonged cell viability at 28°C, and carrageenan at 45°C. Alginate at 1% and  carrageenan at 0.75% showed a stable behavior (superior to the control) in the three evaluated temperatures, so we conclude that they can be used for a  formulation of a liquid inoculant based on the strain C16 of A. brasilense.Key words: Energy of activation, degradation, cell death, kinetics, formulation

    Development and validation of a simple spectrophotometric method for the determination of methyldopa in both bulk and marketed dosage formulations

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    A simple, precise, sensitive, rapid, specific and economical spectrophotometric method was developed to determine methyldopa (MTD) content in bulk and pharmaceutical dosage formulations. The proposed method was based on the formation of a colored product from the nitrosation reaction of MTD with sodium nitrite in an acid medium. The resultant nitroso derivative species reacts further with sodium hydroxide and is converted it into a more stable compound. This yellow nitrosation product exhibited an absorption maximum at 430 nm. Beer's Law was obeyed in a concentration range of 6.37 to 82.81 μg mL-1 MTD with an excellent coefficient of determination (R 2 = 0.9998). No interference was observed from common excipients in formulations. The results showed the method to be simple, accurate and readily applied for the determination of MTD in pure form and in pharmaceutical preparations. The analytical results obtained for these products using the proposed method are in agreement with those of the Brazilian Pharmacopoeia procedure at a 95% confidence level.Desenvolveu-se método espectrofotométrico simples, preciso, sensível, rápido, específico e econômico para a determinação do teor de metildopa (MTD) em matéria-prima e em formulações farmacêuticas. O método proposto baseia-se na formação de um produto colorido resultante da reação de nitrosação da MTD com nitrito de sódio em meio ácido. A espécie resultante (nitroso derivado) reage com hidróxido de sódio e é convertida a um composto mais estável de cor amarela. Este produto exibiu máximo de absorção a 430 nm. A lei de Beer foi obedecida na faixa de concentração de 6,37 a 82,81 μg mL-1 de MTD com excelente coeficiente de determinação (R 2 = 0,9998). Não se observou interferência de excipientes comumente encontrados em formulações farmacêuticas comerciais. Os resultados demonstraram que o método proposto apresenta simplicidade, excelentes precisão e exatidão e pode ser aplicado para a determinação de MTD na sua forma pura e em preparações farmacêuticas. Os resultados analíticos obtidos pelo método proposto estão de acordo com aqueles obtidos pelo método oficial descrito na Farmacopéia Brasileira, a um nível de confiança de 95%

    Guiding principles for development of ACIP recommendations for vaccination during pregnancy and breastfeeding

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    Formulating policy to guide vaccination of women during pregnancy and breastfeeding is challenging because the evidence-base to guide decisions is extremely limited. In the past, ACIP has not provided guidance to workgroups on either the process to formulate policy for this population or the format and language for recommendations. As a result, workgroups have taken a variety of approaches to considering and presenting the issues, resulting in a diversity of recommendations that vary in clarity and underlying rationale. . The principles presented here provide guidance to help standardize both the process of policy formulation and the format and language of recommendations for pregnant and breastfeeding women. All ACIP statements about vaccines and other biologics for use in adolescents or adults should include a background section on vaccination during pregnancy and breastfeeding and provide explicit pregnancy and breastfeeding recommendations using standardized language as outlined below. To arrive at pregnancy and breastfeeding recommendations, ACIP workgroups or subject matter experts charged with developing vaccine statements should review the process suggestions outlined below. These suggestions, while similar to the process generally followed by workgroups, focus specifically on issues related to pregnancy, breastfeeding and decision making in the absence of a strong evidence-base.2008ACIPPrevention and Control704
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