Hygienic evaluation of diflubenzuron-based pesticides in various application technologies

Introduction. In connection with the widespread introduction of new preparative forms of pesticides and methods of their introduction into the environment, the urgent task of the modern period is to minimize the risk of exposure to pesticides on the health of workers and the population-the use of diflubenzuron of low and medium toxicity increases. Therefore, a mandatory criterion for assessing risk is registration tests, carried out during several stages - as hazard identification, hazard characterization, exposure assessment, risk characterization. Purpose of work. To assess the regularities of the formation of the risk of diflubenzuron by exposure and by the absorbed dose, depending on the type of preparative form of pesticides with different technologies of their introduction and regulating safe use measures. Materials and methods. The obtained exposure levels of insecticides based on diflubenzuron in the air and on the skin were compared with the hygienic standards calculated and experimentally established as follows: MPC (mg/m3) in the air of the working area and approximate admissible level (AAL) (mg/cm2) of skin contamination. The exposure level risk was determined by the safety level (SL) SLsumm value. The risk of exposure to insecticides based on diflubenzuron for the operator / user / refueller / pilot / signaller based on the absorbed dose, determined by the safety factor - SLp, and the exposure -SBsumm, is considered acceptable when SLsumm and SLp <1. Results. The paper presents the risk analysis results of the impact of diflubenzuron-based insecticides studied in natural conditions using 27 drugs with different preparative forms and methods (technologies) of their introduction into the environment. The risk of exposure to insecticides (SLsumm) for all technologies is acceptable SL. The risk of absorbed dose (SLp) was more significant regardless of the type of formulation. Wettable powder formulations are more unfavourable to use than other formulations. Conclusion. The conditions for the use of preparations based on diflubenzuron in the technologies of ground boom spraying and fan spraying of field and horticultural crops, in the treatment of field and forest crops by the aerial method, in the treatment of field and horticultural crops in private household plots, in the treatment of champignons in protected ground, compliance with regulations and measures safety meet hygienic requirements.

Obtaining the Controlled Sulphonitrocarburized Layer Phase Compositions, by the Variation of the Solid Powdery Medium Components

Simultaneous saturation of the metallic surface with sulphur, nitrogen and carbon � named sulphonitrocarburizing (SNC) process - may be carried out in a multitude of variants, differ in media state of aggregation which provide the elements in native state, or differ in phase composition. The most commonly used media in SNC process are liquid or gaseous and from standpoint of phase composition, there are media made of compounds generator of the cyanides, representing important source of carbon and nitrogen, and as a sulphur source, may be used iron sulphide, sodium sulphide, sodium thiocyanides or ammonium. Carbamide/urea (CON2H4) it is frequently used in the media composition met in nitro-carburizing or carbo-nitriding process, alongside being added carbonates (sodium or potassium carbonate), thus resulting in cyanides (primary sources of the elements helping superficial saturation of the metallic products), as a result of the reactions which take place at the operating temperature of process. The medium toxicity decreased, based on carbamide used in nitrocarburizing and in particular, SNC process, being possible by carbonates replacing with ammonium chloride. This paper quantify the possibility of using solid powder mixture constituted of carbamide, in order to achieve SNC process of the iron matrix and effects quantification varying the percentage of the solid powdery mixture, so that it becomes possible to control the layer phase composition, by modifying the phase composition of the powder mixture used in thermo chemical processing.

Influence of Man's Activities Level on the Toxicity of Soddy Podzolic Soil

Представлены результаты исследования уровня общей токсичности и микробного токсикоза дерново-подзолистой глееватой почвы при антропогенной нагрузке. Изучение токсичности почвы особенно актуально в агроценозах, где человек в значительной мере регулирует условия произрастания растений. Использование показателей токсичности при оценке агротехнических приёмов позволяет усовершенствовать существующие технологии, чтобы избежать нежелательных сопутствующих эффектов при агрогенном воздействии на агроэкосистемы. Сравнительный анализ полученных результатов показал, что почва опытного участка в начале вегетации имела класс средней и низкой токсичности (индекс токсичности фактора (ИТФ) от 0,63 до 0,82), а в конце вегетации – класс высокой и средней токсичности (ИТФ от 0,35 до 0,55). Оценка микробиологической токсичности почвы исследуемых вариантов опыта по всхожести семян тест-культуры показала в основном средний уровень микробного токсикоза: 69,75% – на индуцированных образцах, 60,97% – на контрольных образцах. Урожайность зелёной массы ярового рапса находилась на невысоком уровне, что могло быть связано с неблагоприятными погодными условиями вегетационного периода и варьировала в пределах от 76 до 218 ц/га. Проведённые исследования по установлению влияния антропогенной нагрузки на токсический статус дерново-подзолистой почвы в условиях Ярославской области показали, что лучшими характеристиками обладают варианты: система отвальной обработки почвы, фон «Органо-минеральный субстрат + NPK» как с внесением гербицида, так и без его применения при возделывании ярового рапса. В этих условиях снижается общая токсичность почвы, статус микробного токсикоза не меняется, что позволяет сохранять почвенное плодородие, иметь оптимальное фитосанитарное состояние и получать качественный урожай выращиваемых культур. The results of the research of general toxicity level and microbial toxicosis of soddy podzolic gleyic soil at man-caused load are presented. The study of soil toxicity is especially important in agrocenoses, where a person largely regulates the conditions of plant growth. The use of toxicity indicators in assessing agricultural practices allows improving existing technologies in order to avoid undesirable concomitant effects during agrogenic effects on agroecosystems. A comparative analysis of the obtained results showed that the soil of the test area at the beginning of the growing season had a medium and low toxicity class (factor toxicity index (FTI) from 0.63 to 0.82) and at the end of the growing season it had a high and medium toxicity class (FTI from 0.35 to 0.55). Assessment of the microbiological toxicity of the soil of test variants under investigation by seed germination of the test-crop showed mainly the average level of microbial toxicosis: 69.75% on the induced samples, 60.97% on the control samples. The yield of green mass of spring rape was at a low level, which could be associated with unfavorable weather conditions of the growing season and varied from 76 to 218 hkg / ha. Researches conducted to establish influence of man's activities on the toxic status of soddy podzolic soil in the conditions of the Yaroslavl region showed that the best characteristics are options: a system of moldboard tillage, background "Organic-mineral substrate + NPK" both with the herbicide application and without its use in the cultivation of spring rape. Under these conditions the general toxicity of the soil decreases, the status of microbial toxicosis does not change which allows maintaining soil fertility, having an optimal phytosanitary condition and obtaining a quality yield of crops grown.

Environmental Performances and Biological Toxicity of Snowpack Water

This work analyzes the state of snowpack in Nizhny Novgorod on the basis of certain chemical performances and integral biological toxicity. Snow samples were obtained in February 2018 along major highways of Nizhny Novgorod. A snow-covered area in Dubrava forestry was selected as reference. The studies demonstrated that the snowpack was characterized by very high concentrations of chlorides and sulfides: in sampling points of the Lower City, the content of chlorides and sulfates varied in the ranges of 24.67–62.36 mg/l and 30.16–62.09 mg/l, respectively, and in sampling points of the Upper City, this variability was 416.82–988.45 mg/l and 280.11–879.22 mg/l, respectively. The content of lead in snowpack in both the Lower City and the Upper City was approximately the same (0.0053 and 0.0048 mg/l). The minimum content of pollutants in snow samples from reference site was characterized by toxicity (10%, V = 6.0%) which was estimated as allowable (toxicity class 1). Snowpack water from the Lower City was characterized generally by medium toxicity (class 2), and sampled in the Upper City – by acute toxicity (59%, V = 26.5%), with regard to the reference (class 3).

Risk Assessment of Two Insecticides on Encarsia formosa, Parasitoid of Whitefly Bemisia tabaci

The assessment of acute toxicity to insect natural enemies is very important for insecticide selection used within integrated pest management (IPM). The acute toxicity of abamectin and imidacloprid against Encarsia formosa, a parasitoid of Bemisia tabaci, was investigated. Abamectin had a high toxicity risk to E. formosa, while imidacloprid showed a medium toxicity risk. When treated with the lethal concentration 30 (LC30) of abamectin, the dwelling time of E. formosa in B. tabaci infested-plant-area (IPA) was significantly lower than in non-infested plant areas (non-IPA). In addition, the frequency of E. formosa entering into the two areas was not significantly different in the LC10 and LC30 treatments. Within the IPA, LC10, and LC30 treatments decreased the dwelling time and entering frequency of parasitoid significantly. For imidacloprid treatments, E. formosa stayed a longer time in the non-IPA than in the IPA when treated with LC30. The frequency of E. formosa entering into the two areas was only slightly different in the LC1, LC10, and LC30 treatments. Within the IPA, LC10 and LC30 treatments were significantly decreased in the dwelling time and the entering frequency of E. formosa. The results indicate that abamectin and imidacloprid have high or medium acute toxicity against E. formosa and a negative sublethal effect on its searching behaviour.

Toxic response of three predatory fishes to four indigenous plant seed extracts

Toxicity of seed extracts of four indigenous plants, Luffa acutangula (Roxb.), Areca catechue (Linn.), Brassica nigra (Linn. Koch.) and Brassica hirta (Monech) was tested on three predatory fishes- Heteropneustes fossilis (Bloch), Anabas testudineus (Bloch) and Channa punctatus (Bloch) under normal laboratory conditions. Due to the toxic effect of different seed extracts and concentrations, mortality rate varied. It also varied from species to species. On the basis of LC50 values of absolute ethyl alcohol extracts, L. acutangula seed extracts were more toxic for H. fossilis and A. testudineus. A. catechue seed extracts were of medium toxicity for all the experimental fishes. B. nigra seed extracts were less toxic whereas B. hirta seed extracts showed differential toxicity being more toxic for C. punctatus, medium for A. testudineus and less toxic for H. fossilis. The susceptibility pattern also varied in the three fish species. In case of L. acutangula, A. catechue and B. nigra seed extracts, the susceptibility was in the same order: H. fossilis > A. testudineus > C. punctatus but the effect of B. hirta seed extracts was reverse. To determine the ichthyotoxicity of the four seed extracts on the three predatory fishes, the present study was undertaken. DOI: http://dx.doi.org/10.3329/cujbs.v6i1-2.17079 The Chittagong Univ. J. B. Sci.,Vol. 6(1&2):27-39, 2011

Repellent and Insecticide Activity of Pelargonium x hortorum against Spodoptera littoralis (Boisd.)

Insecticide and repellent activity of an acetone extract and oil from fresh leaves of Pelargonium x hortorum (cv. Orangesonne) were evaluated against the 2nd and 4th instar larvae of Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae). The oil showed medium toxicity against the 2nd instar and low toxicity against the 4th instar larvae, while the extract showed high significant toxicity at all concentrations tested against the two instars. On the other hand, both oil and extract exhibited highly significant repellency against the two tested instars. Volatile constituents of the oil were also identified by GC-MS analysis.