Efeitos de espécies de timbós (Derris spp.: Fabaceae) em populações de Musca domestica L.

A partir de ensaios com dosagens crescentes, foi avaliado o efeito do pó da raiz de duas espécies de timbó (Derris urucu e D. nicou) sobre populações de larvas de duas linhagens de Musca domestica L., provenientes de duas localidades do Estado de São Paulo, Jaboticabal (Jab) e Brodósqui (Bro). Para obtenção das doses letais foram utilizados ajustes de regressão de acordo com o modelo logístico. D. urucu foi mais eficiente que D. nicou no controle das duas linhagens, sendo necessário mais que o dobro da quantidade de D. nicou para se obter os mesmos efeitos causados com D. urucu. Foi demonstrada a existência de especificidade de ação dos timbós nas linhagens de moscas. D, urucu foi mais eficiente no controle da linhagem Bro, enquanto que D. nicou controlou maior número de indivíduos da linhagem Jab.

Valores de DL50 em peixes e no rato tratados com pó de raízes de Derris spp e suas implicações ecotoxicológicas

Os timbós verdadeiros (plantas do gênero Derris), originários da Amazônia Brasileira, tem demonstrado importância crescente por produzirem uma classe de compostos flavonoídicos relacionados à rotenona, que possuem atividade tóxica para peixes e mamíferos. Neste estudo foi determinado a dose letal 50% (DL50) do extrato alcoólico do pó de Derris spp para três espécies de peixes filogeneticamente diferentes e um mamífero roedor (rato). As DL50 de 2,6 microgramas/ml para Collosoma macropomum (tambaqui), 4,8 microgramas/ml para Oreochromis niloticus (tilápia), 14,2 microgramas/ml para Plecostomus sp (cascudo) e DL50 de 100,0 mg/kg para Rattus norvegicus (rato) denotam acentuadas diferenças entre os valores de DL50, principalmente entre os peixes e o rato. Isto possivelmente é devido a fatores farmaco-cinéticos que se relacionam com as diferentes barreiras teciduais encontradas pelos rotenóides quando administrados pela via oral em mamíferos.

Diferença entre as espécies de Timbó (Derris Spp., Fabaceae) de diferentes regiões da Amazônia no controle da Musca domestica L.

The roots' powder of timbo species collected in different regions of Amazonia that were tested in larvae groupings, didn't produce differential significative effects in two strains of Musca domestica. The two species with the greater number of plants used in the trial were Derris urucu and Derris nicou; the individuals from the species came from regions considered as "forestal refugies" during the Amazonian pleistocene. Among each species the plants varied since that inefficient to control, until plants lethals to the fies. This differential capacity for larvae control among plants of the same species, originated from different regions, suggests that both species had their populations isolated, during the quaternary epoch. In regions or "forestal refugies", where both species were represented, D. urucu was superior to D. nicou in the capacity to control larvae. While among plants from F region (Peruvian-East refuge) of the State of Acre, the two species had convergence in the values of damage to larvae groupings. Among the another species, Derris sp. (yellow timbo or watermelon timbo) didn't show differences in larvae control between samples from the two regions; while the species that was introduced in the Amazonia Denis elleptica showed damage in the larvae groupings similar to the most effective plants of D. nicou and D. urucu.

Teores de rotenona em Clones de Timbó (Derris Spp. Fabaceae) de diferentes regiões da Amazônia e os seus efeitos na emergência de Imagos em Musca Domestica L

The rotenone contents analysis in clones of three timbó species permited the classification of these plants based on their efficiency to control Musca domestica larvae. The results showed significant correlations between the rotenone contents in the Derris urucu and D. nicou clones with the capacity to control the larvae. The plants with high rotenone contents were more effective. The rotenone contents, the effect of Derris species clones on the flics and the localization of the plants origin, showed that among the plants could have happened a populational isolation in the Amazonia during the pleistocene epoch. In Derris sp., that presented lower rotenone contents and was ineffective to control of the larvae, these differences were not observed.

Atividade inseticida e Modos de Ação de Extratos Vegetais Sobre Mosca Branca (Bemisia tabaci)

Insecticide potential and efficaciousness of vegetal extracts concentrations from six botanic families in three different modes were analyzed on the nymphs of the silverleaf whitefly Bemisia tabaci (Genn. 1889) on a tomato plantation Lycopersicon esculentum Mill. Nymph breeding was kept in cherry tomato shrubs. Test solutions were obtained from successive extractions with ethanol and evaporation in a rotary evaporator. Tests consisted of 10 solutions in four concentrations (500; 1,000; 1,500 and 3,000 μg/mL) and control treatment (distilled water + 1% DMSO) under three different modes of activity, namely, contact, translaminar and systemic. Experimental design was totally randomized with four repetitions and eleven treatments. Means were compared by Scott-Knott test at 5% probability and lethal concentrations (CL50) were calculated by POLO. In the case of contact activity mode, all extracts had efficiency above 50% with the highest concentration (3,000 μg/mL) in which the highest efficiency for all extracts tested was verified. There was a need for dose increase in translaminar activity mode for similar results, whereas in the case of systemic activity the best performance was obtained with extracts of Nerium oleander, Derris amazonica and Ipomoea carnea. Extracts of the last two caused a higher percentage when compared with that of other extracts in all activity modes lower than CL50.