RESUMO

Bio-insecticides have been increasingly used worldwide as ecofriendly alternatives to pesticides, but data on their effects in non-target freshwater organisms is still scarce and limited to insects. The aim of this study was to determine the lethal and sub-lethal effects of the bio-insecticides Bac Control (based on Bacillus thuringiensis kurstaki-Btk) and Boveril (based on Beauveria bassiana-Bb) on regeneration, behavioral, and reproductive endpoints of the freshwater planarian Girardia tigrina. The estimated LC50-48h were > 800 mg a.i./L for Btk and 60.74 mg a.i./L for Bb. In addition, exposure to Btk significantly decreased locomotion and feeding activities of planarians (lowest observed effect concentration (LOEC) of 12.5 mg a.i./L Btk) and fecundity rate (LOEC = 3.12 mg a.i./L Btk), whereas exposure to Bb significantly delayed regeneration (LOEC = 0.75 mg a.i./L Bb) and decreased fecundity rate (1.5 mg a.i./L Bb) of planarians. Thus, both bio-insecticides induced deleterious sub-lethal effects on a non-insect freshwater invertebrate species. However, only Bb-based formulation affected the survival, fecundity rate, and regeneration at concentrations below the maximum predicted environmental concentration (PEC = 247 mg/L). Thus, care should be taken when using such formulations as alternatives to chemical insecticides near aquatic ecosystems.

Assuntos

RESUMO

The mechanism of regeneration does not start to restore the wound until its corresponding epimorphic phase. A bioestimulation of tissues and cells by laser radiation depends on the wavelength, on the dose, and on the intensity of the light. The goal of this work was to verify the effect of the low power laser at 660 nm on the regenerative process of Girardia tigrina. The specimens were maintained in the laboratory under a temperature ranging from 19° up to 24 °C for 21 days. The planarians were anesthetized by placing them on ice and then cut them with a scalpel. The three treatments were as following: animals individually irradiated with 14 sessions with 1 minute duration (treatment 1), 14 sessions with 3 minutes duration (treatment 2), and without irradiation (control). The planarians were amputated and divided in three study treatments: a control group (without radiation), and two other treatments: irradiated for 1 minute, and irradiated for 3 minutes. The animals were irradiated with diode laser (660 nm) with 3.3 ± 0.3 mW of power, using 0.94 mW.mm-2 power density for each irradiation procedure. During the experiment, 14 irradiation sessions were undertaken. The specimens were fixed in Bouin, and stained with hematoxyline and eosin. From observation and histological analysis, it was possible to assess the effects of interaction between laser and tissue. The head fragment after 1 minute of irradiation presented a better organized tissue scheme, when compared with the other treatments. Aspects of the body fragments submitted to 3 minutes of light treatment were very similar to fragments that had not been injured. It can be concluded that there are changes in the quality of regeneration when treated with low power laser under the conditions mentioned above.

O mecanismo de regeneração não restaura a ferida até sua fase epimórfica correspondente. A bioestimulação de tecidos e células por radiação laser depende do comprimento de onda, da dose e intensidade de luz. O objetivo deste trabalho foi verificar o efeito do laser de baixa potência (660 nm) no processo regenerativo de Girardia tigrina. Estes vermes têm uma elevada capacidade de regeneração. Os espécimes foram mantidos em laboratório sob uma temperatura de 19° a 24 °C por 21 dias. As planárias foram anestesiadas com gelo e amputadas com bisturi. Os 3 tratamentos foram compostos de: animais individualmente irradiados com 14 sessões de 1 minuto de duração (tratamento 1), com 14 sessões de três minutos de duração (tratamento 2) e não irradiados (controle). Elas foram irradiadas com laser diodo (660 nm) 3,3 ± 0,3 mW potência, usando 0.94 mW.mm-2 de densidade de potência para cada irradiação. Durante o experimento foram realizadas 14 sessões. Os espécimes foram fixados em Bouin e corados com hematoxilina e eosina. Com base nas observações e análise histológica, foi possível avaliar os efeitos da interação entre laser e tecido. O fragmento cabeça após 1 minuto de irradiação mostrou um tecido melhor organizado quando comparado com outros tratamentos. Os aspectos dos fragmentos corpo após 3 minutos de irradiação foram muito similares para os fragmentos que não sofreram injúria. Existem mudanças na qualidade de regeneração quando tratadas com laser nas condições acima mencionadas.

Assuntos

RESUMO

The mechanism of regeneration does not start to restore the wound until its corresponding epimorphic phase. A bioestimulation of tissues and cells by laser radiation depends on the wavelength, on the dose, and on the intensity of the light. The goal of this work was to verify the effect of the low power laser at 660 nm on the regenerative process of Girardia tigrina. The specimens were maintained in the laboratory under a temperature ranging from 19° up to 24 °C for 21 days. The planarians were anesthetized by placing them on ice and then cut them with a scalpel. The three treatments were as following: animals individually irradiated with 14 sessions with 1 minute duration (treatment 1), 14 sessions with 3 minutes duration (treatment 2), and without irradiation (control). The planarians were amputated and divided in three study treatments: a control group (without radiation), and two other treatments: irradiated for 1 minute, and irradiated for 3 minutes. The animals were irradiated with diode laser (660 nm) with 3.3 ± 0.3 mW of power, using 0.94 mW.mm-2 power density for each irradiation procedure. During the experiment, 14 irradiation sessions were undertaken. The specimens were fixed in Bouin, and stained with hematoxyline and eosin. From observation and histological analysis, it was possible to assess the effects of interaction between laser and tissue. The head fragment after 1 minute of irradiation presented a better organized tissue scheme, when compared with the other treatments. Aspects of the body fragments submitted to 3 minutes of light treatment were very similar to fragments that had not been injured. It can be concluded that there are changes in the quality of regeneration when treated with low power laser under the conditions mentioned above.

O mecanismo de regeneração não restaura a ferida até sua fase epimórfica correspondente. A bioestimulação de tecidos e células por radiação laser depende do comprimento de onda, da dose e intensidade de luz. O objetivo deste trabalho foi verificar o efeito do laser de baixa potência (660 nm) no processo regenerativo de Girardia tigrina. Estes vermes têm uma elevada capacidade de regeneração. Os espécimes foram mantidos em laboratório sob uma temperatura de 19° a 24 °C por 21 dias. As planárias foram anestesiadas com gelo e amputadas com bisturi. Os 3 tratamentos foram compostos de: animais individualmente irradiados com 14 sessões de 1 minuto de duração (tratamento 1), com 14 sessões de três minutos de duração (tratamento 2) e não irradiados (controle). Elas foram irradiadas com laser diodo (660 nm) 3,3 ± 0,3 mW potência, usando 0.94 mW.mm-2 de densidade de potência para cada irradiação. Durante o experimento foram realizadas 14 sessões. Os espécimes foram fixados em Bouin e corados com hematoxilina e eosina. Com base nas observações e análise histológica, foi possível avaliar os efeitos da interação entre laser e tecido. O fragmento cabeça após 1 minuto de irradiação mostrou um tecido melhor organizado quando comparado com outros tratamentos. Os aspectos dos fragmentos corpo após 3 minutos de irradiação foram muito similares para os fragmentos que não sofreram injúria. Existem mudanças na qualidade de regeneração quando tratadas com laser nas condições acima mencionadas.