Effects of the pesticides chlorpyriphos, metsulfuron-methyl, and thiamethoxam on ant communities in wheat crop

Ants are important components of food webs in several ecosystems. In anthropic areas, they can be used as bioindicators of the environmental impacts caused by many factors or in the evaluation of the dynamics of the recovery of an area after a certain disturbance. In this context, ants can be used as bioindicators in studies on the evaluation of environmental disturbances caused by pesticide use. Thus, the present work investigated the environmental impacts caused by the application of the insecticides chlorpyriphos and thiamethoxam and the herbicide metsulfuron-methyl in the community of ants in wheat crop (Triticum aestivum L.). The data were collected by pitfall traps and Berlese funnels. A Principal Response Curve was used for a relative abundance analysis. In addition, diversity index and richness were calculated for ant communities. The presence of six families, 11 tribes, 15 genera, and 19 morphospecies of ants belonging to the guilds of fungivorous, omnivorous, and predaceous ants were observed in the soil of the wheat crop. The insecticides chlorpyriphos and thiamethoxam reduced the richness, diversity, and relative abundance of ants of all the guilds on the surface and inside the soil. The effect of the herbicide metsulfuron-methyl on the community of ants was lower than the impact of the insecticides on these insects.

Preliminary study on thiamethoxam degrading bacteria isolated from corn plantation

Aims@#Thiamethoxam (THIA) is a pesticide that has been widely used for its effectiveness in controlling and preventing insect pests. However, the use of THIA diffused in soil, surface and groundwater pose severe toxicity to the ecosystem. The hazardous pollution caused by the toxicity of THIA demands for remediation to ensure degradation of THIA into its safe constituent elements. Thus, the aim of this study is to isolate and identify potential THIA degraders for future bioremediation.@*Methodology and results@#Bacteria were isolated from soil sample collected at a corn plantation which utilizes THIA as a source of pesticide. Overall, two bacterial isolates were isolated from the soil sample. The bacterial isolates were screened and identified for their ability to degrade pesticide by culturing in minimal salt media (MSM) supplemented with 50 mg/L THIA. The growth of isolates was observed and analyzed through spectrophotometry analysis, standard plate count method and pH value of culture medium. As a result, isolate THIA 1 had been found to possess the ability to degrade pesticide as it showed a high rate in growth of bacteria compared to its controls. Meanwhile, isolate THIA 2 showed no degrading activities while under treatment as it showed similar rate of growth towards its control. Isolate THIA 1 was identified as Acinetobacter sp. UMTFA THIA 1.@*Conclusion, significance and impact of study@#The isolation and identification of the pesticide degrading bacteria will provide promising source of pesticide degrading enzyme that can be further developed for enzymatic pesticide biodegradation. This will pave the way forward in bioremediation where new effective degradation tools can be developed for pesticide residue which otherwise lead to serious ecological problem.

Exposure of Apis mellifera (Hymenoptera: Apidae) to pollen grains of soybean plants (Glycine max L) originated from treated seeds / Exposição de Apis mellifera (Hymenoptera: Apidae) aos grãos de pólen de plantas de soja (Glycine max L) originadas de sementes tratadas

Residues of plant protection products have been reported in floral resources such as pollen, but the potential risks of pollinator exposure are still unclear. Therefore, studies are needed to assess the risk of exposure/intoxication of bees, as they collect these resources to maintain their colony. The present study used a randomized design with five treatments: thiamethoxam, clothianidin, imidacloprid, fipronil, and a control. Pollen was collected from two soybean plants per repetition during their entire flowering period, mixed with 8 g of sugar cake (distilled water + sugar), and offered to adult bees that were then followed for the assessment of mortality over time (1, 2, 4, 8, 16, 24 and 32 h after initial exposure). Among the generalized linear models evaluated, the beta binomial model was the best fit. The treatments were compared within each time period by overlapping credibility intervals using Bayesian inference. The probability of bee mortality was low in the first hours of evaluation and gradually increased over time in all chemical treatments. When comparing the means of the beta-binomial model, no statistical differences among treatments was observed, indicating a mortality similar to that of the control group.(AU)

Resíduos de produtos de proteção de plantas têm sido relatados em recursos florais como o pólen, mas os potenciais riscos da exposição aos polinizadores ainda não estão claros. Portanto, tornam-se necessários estudos para avaliar o risco da exposição/intoxicação das abelhas, já que necessitam destes recursos para a manutenção da colônia. O presente estudo utilizou um delineamento inteiramente ao acaso com cinco tratamentos: tiametoxam, clotianidina, imidacloprid, fipronil e testemunha. O pólen foi coletado durante todo o período de floração de duas plantas de soja por repetição e incorporado a 8 g de pasta candi (água destilada + açúcar), e oferecido às abelhas adultas e logo após foi avaliada a mortalidade ao longo do tempo (1, 2, 4, 8, 16, 24 e 32 h após a exposição inicial). Dentre os modelos lineares generalizados testados o modelo do tipo beta binomial foi o que melhor se ajustou. Os tratamentos foram contrastados dentro de cada intervalo de tempo pela sobreposição dos intervalos de credibilidade através Inferência Bayesiana. A probabilidade de mortalidade das abelhas foi pequena nas primeiras horas de avaliação, aumentando gradativamente ao longo do tempo em todos os tratamentos. Ao comparar as médias do modelo beta-binomial, não foram observadas diferenças estatísticas entre os tratamentos, indicando uma mortalidade padrão inclusive na testemunha.(AU)

Occurrence regularity and integrated control of leaf miner in safflower / 中国中药杂志

Leaf miner is one of the major pests on safflower, which causes yield loss and poor quality seriously. "Weihonghua", "nine safflower varieties" and "three chemical insecticides" as materials that used to evaluate variety and regularity of leaf miner, safflower resistant level, and different proportions insecticides in field efficiency test. The results showed that Liriomyza sativae and L. huidobrensis accounted for 80%, the peak period of two pests was all in July; but Phytomyza horticola is relative less, its peak period occured in June. Three were great difference of resistance to leaf miner among safflower varieties, FQ12 and YJ65 expressed higher resistibility to leaf miner by ratio method. With abamectin 2% emulsifiable concentrate diluted for 2 000 times, or the mixture three insecticides(bifenthrin 20% water emulsions, thiamethoxam 25% water dispersible granule, abamectin 2% emulsifiable concentrate=1∶1∶1) diluted for 3 000 times, which were sprayed on leaves at squaring stage and lethal rate was 96% after 48 h in the study. Through comparative study on the variety and regularity of leaf miner, screen for resistant varieties to leaf miner and for high efficiency pesticide. The study provides theoretical basis and reference for integrated pest management of leaf miner.

Avaliação do efeito de inseticidas sobre a joaninha Hippodamia convergens Guérin-Meneville (Coleoptera: Coccinellidae) em algodoeiro / Evaluation of the effect of insecticides on lady beetles Hippodamia convergens Guérin-Meneville (Coleoptera: Coccinellidae) in cotton plant

A associação dos métodos químico e biológico no controle de pragas é fundamental na sustentabilidade do sistema agrícola, auxiliando a redução de químicos derivados de petróleo. O objetivo do trabalho foi avaliar o efeito de inseticidas sobre o coccinelídeo predador Hippodamia convergens, na cultura do algodoeiro, em condições de laboratório e de campo. Foram estabelecidos os seguintes tratamentos, expressos em g ou mL de p.c. do inseticida por hectare: flonicamida a 50, 80 e 150 g, tiametoxam a 200 g, acetamiprido a 150 g, imidacloprido a 250 mL e testemunha sem aplicação. A avaliação do efeito dos inseticidas aplicados diretamente e indiretamente (efeito de contato em resíduo seco do inseticida) sobre H. convergens, foi realizada por meio da quantificação de insetos sobreviventes após a aplicação. Com base nos resultados dos experimentos, pode-se concluir que dentre os inseticidas avaliados, flonicamida ocasionou a menor mortalidade de H. convergens. Os inseticidas tiametoxam, acetamiprido e imidacloprido apresentaram comportamento semelhante, acarretando alta mortalidade de H. convergens.

The combination of chemical and biological methods to control pests is essential to ensure the sustainability of agricultural system, to reduce using of chemicals products. The objective this work was to evaluate the effects of insecticides on the coccinellid predatory Hyppodamia convergens, the cotton plant, in conditions laboratory and field. Were the following treatments established, expressed in g or mL of active ingredient of insecticide per hectare: flonicamid to 50, 80 and 150 g, thiamethoxam at 200 g to 150 g acetamiprid, imidacloprid to 250 mL and control without application. The evaluation effect of insecticides applied directly and indirectly (residual effects on leaves) on H. convergens, was performed by quantification of insects survived to 7 days after application. Based on the results of experiments, we can conclude that among the insecticides evaluated, flonicamid caused the lower mortality of H. convergens. The insecticides thiamethoxam, acetamiprid and imidacloprid showed similar behavior, causing high mortality of H. convergens.

Efeito fisiológico do inseticida thiamethoxam na cultura da cana-de-açúcar / Physiological effect of the insecticide thiamethoxam on sugarcane

Com a finalidade de avaliar o efeito fisiológico de thiamethoxam no desenvolvimento inicial de plantas de cana-de-açúcar, foram realizados dois experimentos. O primeiro conduzido em caixas plásticas do tipo gerbox (3,5 x 11 x 11 cm) contendo substrato, aplicou-se thiamethoxam em toletes de cana-de-açúcar, nas doses: 0, 100, 150 e 200 g de ingrediente ativo (i.a.).ha-1. O segundo experimento foi realizado em tubos de PVC (0,2 x 1,20 m), preenchido com solo, utilizaram-se seis doses de thiamethoxam (0, 50, 100, 150, 200 e 250 g i.a.ha-1) em mudas de duas variedades (RB867515 e SP80-1816). Avaliou-se a parte área e o sistema radicular das plantas aos 30 dias após a aplicação do inseticida, no primeiro experimento e aos 130 dias no segundo. Observou-se que no primeiro experimento as características altura, diâmetro e massa seca da parte área não foram alterados em razão da aplicação do inseticida nos toletes de cana-de-açúcar, porém, nos tratamentos com thiamethoxam houve um incremento na massa seca das raízes de até 3,7 vezes mais. No segundo experimento, thiamethoxam proporcionou aumento no diâmetro das plantas e incremento na massa seca das raízes da variedade RB867515 de até 72,69%. No entanto, o comprimento do sistema radicular e a massa seca da parte aérea não foram alterados pela aplicação do inseticida nas mudas.

With the purpose to evaluate the physiological effect of thiamethoxam on the initial development of sugarcane, two experiments were carried out. In the first, carried out in Gerbox-type plastic boxes (3.5 x 11 x 11 cm) containing substrate, thiamethoxam was applied on sugarcane cuttings at the doses of 0, 100, 150 and 200 g of active ingredient per hectare (a.i.ha-1). The second experiment was carried in PVC pipes (0.2 x 1.20 m), filled with soil. Six doses of thiamethoxam (0, 50, 100, 150, 200 and 250 g a.i.ha -1) were used on two cultivars (RB867515 and SP80-1816).Roots and shoots were evaluated 30 days after the insecticide application in the first experiment and after 130 days in the second one. In the first experiment it was observed that the height characteristics, diameter and dry mass of shoots did not change through the use of the insecticide on sugarcane cuttings, however, in the treatments with thiamethoxam there was an increase on roots dry mass up to 3.7 times more. In the second experiment, thiamethoxam increased the diameter of shoots and the root dry mass of RB867515 cultivar up 72.69%. However, the length of the root system and the shoot dry mass were not changed by insecticide application in seedlings.