The influence of caffeine and thymol on the survival, growth and reproduction of Subulina octona (Brugüière, 1789) (Mollusca, Subulinidae)

Subulina octona is a terrestrial snail which serves as an intermediate host for the parasites. It is also an agricultural pest. The aim of this work was to assess, during 120 days, the effects of caffeine and thymol at 2.5 g/L and 5 g/L on the hatchability, survival after hatching, growth and reproduction of S. octona under the laboratory conditions. A total of 240 eggs, 240 juveniles aged 10-day-old, and 240 aged 30-day-old were tested. The results showed that thymol (at 2.5 g/L and 5 g/L) and caffeine (at 5 g/L) acted as ovicides. In the 10-day-old juveniles, caffeine at 5 g/L caused 25 percent mortality and at 2.5 g/L it caused 30 percent mortality. Thymol at 2.5 and 5 g/L caused 20 and 22.5 percent mortality, respectively. In the 30-day-old juveniles, caffeine at 5 g/L caused 47.5 percent mortality.

Subulina octona é um molusco terrestre que atua como hospedeiro intermediário de parasitos. Também atua como praga agrícola. O objetivo deste trabalho foi avaliar, durante 120 dias, o efeito da cafeína e do timol a 2,5g/L e a 5g/L, sobre a eclodibilidade, a sobrevivência após a eclosão, crescimento e a reprodução de S. octona em condições de laboratório. Foram testados 240 ovos, 240 jovens com 10 e 30 dias de vida. Os resultados dos testes mostraram que o timol (5g/L e 2,5g/L) e a cafeína a 5g/L atuaram como ovicida. Nos jovens com 10 dias de vida a cafeína à 5g/L provocou uma mortalidade de 25 por cento e a 2,5 g/L 30 por cento. O timol a 2,5g/L e 5g/L provocou 20 e 22,5 por cento de mortalidade, respectivamente. Nos jovens com 30 dias de vida a cafeína a 5g/L causou 47,5 por cento de mortalidade. Esses resultados sugerem novos estudos no campo.

Mitodepressive and clastogenic effects of aqueous extracts of the lichens Myelochroa lindmanii and Canoparmelia texana (Lecanorales, Parmeliaceae) on meristematic cells in plant bioassays

The cytotoxicity effect of aqueous extracts of the lichens species Myelochroa lindmanii and Canoparmelia texana (Lecanorales, Parmeliaceae) were evaluated using meristematic cells of lettuce (Lactuca sativa) and maize (Zea mays). The seasonal effect was also evaluated. Extracts of M. lindmanii and C. texana inhibited root growth and/or percentage germination, possibly due to alterations in the cell cycle. The M. lindmanii extract showed anti-mitotic effects and blocked the cell cycle in metaphase so that c-mitosis and cells with chromosome duplication were produced. The C. texana extract appeared to hinder cell division, increasing the number of interphase cells. In addition, both extracts caused an increase in percentage of cell death. Clastogenic effects were also observed, such as sticky chromosomes, bridges, fragments and later segregation. Both lichen species are thus potential sources of biologically active substances with possible applications in biology, medicine and agronomy.