Triagem de plantas do cerrado e pantanal sul- matogrossense e ação do 3-o-tigloilmelianol isolado de guarea kunthiana (meliaceae) sobre rhipicephalus (boophilus) microplus (canestrini, 1887) (acari: ixodidae)
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2012-08-30
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Universidade Federal de Goiás
Resumo
Dairy and beef cattle farming are vital pillars of the Brazilian economy. Among the threats to this activity are ectoparasites, most notably the cattle tick R. microplus (Ixodidae), which has acquired resistance to synthetic acaricides. Plants from Brazil’s Cerrado biome and from the South Matto Grosso Pantanal have been the object of biomonitoring studies in insects, and some have shown activity. The present research aimed to carry out triage for 73 ethanolic extracts, from 24 families and 44 plant species from these biomes, and to evaluate the effect of the compound 3-O-tigloilmelianol isolated from Guarea kunthiana (Meliaceae) on R.microplus. In the triage, the extracts were tested at 0.20% in vitro, on engorged R.microplus females. Following the index of efficacy, extracts from the fruit of G. kunthiana (Meliaceae) (99.08%), stem of Nymphaea amazonum (Nymphaeaceae) (51.67%), leaves of Strychnos pseudoquina (Loganiaceae) (48.02%) and stem of Ocotea lancifolia (Lauraceae) (34.52%) were selected. To understand alterations in the ovaries caused by 3-O-tigloilmelianol, three groups of 24 specimens were used, including controls and those treated with the substance at 0.01% in immersion test for five minutes, which were then dried and placed in BOD at 27oC with 90% UR. After 24, 48 or 72 h each group was dissected and the ovaries were placed in Eppendorfs containing buffer solution for 24 h, then embedded in historesin, cut to a thickness of 2 μm, placed on glass sides, stained with toluidine blue and observed under microscope. In the biometrical analysis a significant reduction (50%) was noted in the gonadosomatic index in the samples after 48 and 72hs after exposure, compared to the control. There was a significant reduction (22 to 60%) in the number of oocytes I, IV and V in the treatment groups after 24 and 72h of exposure in relation to the control. Oocytes II were not reduced, and oocytes III were reduced only at 24 h of exposure. The greatest diameters of cytoplasm and nuclei of oocytes I were reduced at 72 h of exposure, and for the lowest diameter of the cytoplasm the reduction was seen at 24 h of exposure. In oocytes II only the greatest diameter of the nucleus was reduced in the group immersed for 24 h. Oocytes III and V showed no alteration in diameter and those from phase IV showed a reduction in the greatest diameter of the cytoplasm. The 3-O-tigloilmelianol was tested on the larvae at 0.01 to 0.00125% using the ‘sandwich’ test with about 300 examples 15 to 21 days after hatching. Mortality was evaluated after 24, 72 and 168 h, but without any action being recorded. The 3-O-tigloilmelianol was tested on the metalarvae and metanymphs, using the immersion test, using 100 examples per concentration between treatments and controls. The ecdyses were recorded ten times. It was noted that there was 60% reduction in ecdysis in metalarvae and 20% in metanymphs at the highest concentration. The results of this research showed that these plants from the Cerrado and the Pantanal are promising in the triage study. The discovery of the action of the protolimonoid 3-O-tigloilmelianol isolated from G. kunthiana on the reproductive cycle of R.microplus justifies its prospection as a possible alternative in the control of this tick.
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Bovino , Fitoterápico , Parasitoses , Teleóginas , Vegetais , Bovine , Phytotherapeutic , Parasitosis , Engorged females , Plants
Citação
BARBOSA, Carolina da Silva. Triagem de plantas do cerrado e pantanal sul- matogrossense e ação do 3-o-tigloilmelianol isolado de guarea kunthiana (meliaceae) sobre rhipicephalus (boophilus) microplus (canestrini, 1887) (acari: ixodidae). 2012. 67 f. Tese (Doutorado em Ciência Animal) - Universidade Federal de Goiás,Goiânia, 2012.