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.

Ação do laser infravermelho em suspensões de Streptococcus mutans / Infrared laser action on Streptococcus mutans suspensions

Introdução: os benefícios do laser infravermelho no tratamento da mucosite oral e no controle da dor na disfunção da articulação temporomandibular são bem reconhecidos e já aplicados clinicamente. Porém, o efeito dessa terapia em bactérias da cavidade oral ainda é incerto. Objetivo: analisar o efeito do laser infravermelho Diodo de Arseneto de Gálio Alumínio (AsGaAl) (LIV) nos níveis de suspensões de Streptococcus mutans UA159. Método: o laser de baixa potência infravermelho e comprimento de onda predominante de 880nm (Therapy XT-ESTM, DMC Equipamentos) foi utilizado com potência de 100mW e diâmetro da ponteira 0,0280 cm². A suspensão bacteriana foi ativada em estufa bacteriológica a 37ºC e 5% CO2, durante um período de 18 horas, ajustada para a concentração de 1-2 x 108 unidades formadoras de colônia/mL (UFC/mL). As suspensões foram submetidas aos seguintes protocolos experimentais e controle: grupo 1) LIV 30s; grupo 2) LIV 60s; grupo 3) LIV 90s; grupo 4) NaCl 0,9%. Em seguida, uma alíquota foi retirada para a diluição seriada e semeadura das amostras. As placas permaneceram em estufa bacteriológica a 37ºC e 5% CO2 durante um período de 48 horas para posterior contagem das UFC/mL. O estudo foi conduzido em triplicata. Resultados: os resultados, a seguir, estão expressos em Log UFC/mL: grupo 1 (8,42±0,16); grupo 2 (8,41±0,03); grupo 3 (8,37±0,11); grupo 4 (8,37±0,16). Não foi observada diferença estatisticamente entre os grupos (p>0,05). Conclusão: o estudo mostrou que o laser infravermelho, nas condições experimentais usadas, não demonstrou ação na viabilidade de S. mutans presentes em suspensões in vitro.

Introduction: The benefits of infrared laser in the treatment of oral mucositis and pain control in temporomandibular joint dysfunction are well recognized and applied clinically. However, the effect of this therapy on oral cavity bacteria is still uncertain. Objective: Analyze the effect of infrared laser Gallium Arsenide Diode (AsGaAl) (LIV) on the levels of Streptococcus mutans UA159 suspensions. Method: Low-power infrared laser with predominant wavelength of 880nm (Therapy XT-ESTM, DMC Equipment) was used with 100mW output power and tip diameter 0.0280cm².The bacterial suspension was activated in a bacteriological oven at 37 ° C and 5% CO 2 for a period of 18 h, adjusted to the concentration of 1-2 x 108 colony forming units / mL (CFU / mL).The suspensions were submitted to the following experimental protocols and control: Group 1)LIV 30s; group 2)LIV 60s; Group 3)LIV 90s; Group 4)saline solution. After that, an aliquot was taken for serial dilution and plating of the sample. The plates were kept in a bacteriological oven at 37°C and 5% CO2 for 48 hours for subsequent cfu/ml counts. The study was conducted in triplicates. Results: The following results are expressed in Log ufc/mL: Group 1 (8.42 ± 0.16); Group 2 (8.41 ± 0.03); Group 3 (8.37 ± 0.11); Group 4 (8.37 ± 0.16). There was no statistically significant difference between groups (p>0.05). Conclusion: In the experimental tested conditions, the study showed that the infrared laser had no action on the viability of S. mutans suspensions in vitro.