Caracterização morfológica, molecular e biológica de fungos patogênicos a invertebrados dos Cerrados de Goiás
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2010-02-23
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Universidade Federal de Goiás
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The high biodiversity of fungi pathogenic to invertebrates and their potential to control pests until today not well known emphasize the importance to look for new effective species
and strains. The Cerrado is considered one of the hotspots of biodiversity and little is known about the occurrence and the potential of fungi pathogenic to invertebrates found in this biome. In the present study a survey of fungi was carried out in different areas of the Cerrado of Goiás. Samples of soil, slurry, water and moribund or dead insects were collected for isolation of fungi. Vectors of medical importance such as triatomines (Triatoma infestans and Rhodnius neglectus), mosquitoes (Aedes aegypti and Culex quinquefasciatus), ticks (Riphicephalus (Boophilus) microplus) and snails (Biomphalaria glabrata) were used as baits for isolation of fungi. After isolation fungi were morphologically identified and included in the collection ofInstitute of Tropical Pathology and Public Health, Federal University of Goiás. Some isolates of Evlachovaea and Metarhizium were molecularly characterized and activity tested against T. infestans. A total of 561 samples of soil (440), slurry (106) and water (15) was collected in different areas of Goiás State. Concerning samples collected at Fazenda Santa Branca, 68 isolates of pathogenic fungi were obtained and identified as belonging to the genera Aspergillus, Beauveria, Cladosporium, Evlachovaea, Fusarium, Gliocladium, Isaria,Lecanicillium, Metarhizium, Paecilomyces, Pochonia and Trichoderma. An total of 106
isolates of Metarhizium spp. and 6 of Evlachovaea spp. were sampled in other areas, being 65isolates of Metarhizium and 1 of Evlachovaea from the Ema National Park, 33 and 1 from the
Northern portion of Goiás state, and 8 and 4 from the Silvânia National Forest, respectively.Most fungi were isolated from soils using triatomines as baits. Fungi from genera Aschersonia,
Batkoa, Beauveria, Cordyceps, Evlachovaea, Fusarium, Lecanicillium, Pandora and Torrubiella were isolated from mycosed cadavers. All tested isolates of Metarhizium spp. and
Evlachovaea spp. induced high mortality of T. infestans in relative humidity (RH) close to saturation. The lowest values for lethal time of 90% were 6.6 d (6.3 7.1 d; M. robertsii IP 34)and 7.1 d (6.7 7.8 d; Evlachovaea IP 141), after treatment of T. infestans and exposure to RH> 98%. The lethal concentration to obtain 50% mortality (LC50) of IP 34 was 2.8x103 (C.I. 4.4x102-4.6x103) and the LC90 was 7.2x103 (C.I. 4.4x103-6.4x105) CFU/cm2 at 10 d p.i. In RH
75% mortality of triatomines did not exceed 20%. Morphological studies and sequencing of the ITS and TEF region of Evlachovaea isolates showed that genus Evlachovaea must be synonymized with Isaria, and that the largest group of isolates previously identified as Evlachovaea are I. cateniannulata, whereas the smaller group is probably a new species of Isaria. The sequencing of the TEF and ITS regions showed that Metarhizium isolates belong to species M. anisopliae, M. robertsii, M. flavoviride var. pemphigi, and the largest group of Metarhizium isolates can be a new species of Metarhizium or a M. anisopliae variety. The results confirmed that in the Cerrado a high diversity of fungi is present and some of them, in special M. robertsii (IP 34) and Evlachovaea (IP 141) have potential for biological control of T. infestans
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ROCHA, Luiz Fernando Nunes. Morphological, molecular biological and fungal pathogenic to invertebrates of the Cerrado in Goiás. 2010. 27 f. Tese (Doutorado em Ciências da Saúde) - Universidade Federal de Goiás, Goiânia, 2010.