Luis G. Leite

In vitro production of hyphal bodies of the mite pathogenic fungus Neozygites floridana

The fungus Neozygites floridana is a path- ogen commonly associated with the cassava green mite (CGM), Mononychellus tanajoa, and the two- spotted spider mite (TSM), Tetranychus urticae, in South America. Difficulty in culturing N. floridana in vitro has hampered its development as a bioacaricide. A Colombian isolate from TSM was multiplied in TSM and hyphal bodies from infected specimens were inoculated into 18 mycological and tissue cul- ture media. Graces insect tissue culture medium plus 0.33% lactalbumin hydrolysate and 0.33% yeastolate (GS) afforded vigorous multiplication of hyphal bod- ies (over 106 /mL). The number of hyphal bodies increased with aeration. Final concentration of hy- phal bodies was not affected by fetal bovine serum (FBS), but growth was somewhat enhanced. Hyphal bodies produced germ tubes when transferred from GS medium to Graces medium plus 10% FBS and shaken at 200 rpm for 24 h. The germinated hyphal bodies, when placed on water agar, produced pri- mary conidia from which capilliconidia were pro- duced. These capilliconidia were infective to both TSM and CGM.

Effect of salts, vitamins, sugars and nitrogen sources on the growth of three genera of Entomophthorales : Batkoa , Furia , and Neozygites

Entomophthorales pathogenic to insects and mites often cause epizootics in their host populations, but some have been difficult to culture in vitro and, therefore, to develop as biopesticides. Graces insect cell culture medium supplemented with lactalbumin hydrolysate and yeastolate has allowed growth of several species which until recently were referred to as obligate parasites. The research reported here was designed to evaluate the effects of the salts, vitamins and amino acids used to prepare the insect cell culture medium on in vitro growth of Batkoa sp. and Furia sp., pathogens of the spittlebug pests of pasture and sugar-cane in Brazil, and Neozygites floridana, a pathogen of several mite species. Also, several sources of carbon and nitrogen were examined. Batkoa sp., Furia sp. and N. floridana were similar concerning their growth patterns in a basic medium with added salts, vitamins and amino acids, as well as with a combination of all three compoments. The addition of salts to the basic medium of sugars plus lactalbumen hydrolysate and yeastolate caused a significant increase in biomass production of the three fungal species. The addition of vitamins and amino acids had less effect. Batkoa sp., Furia sp. and N. floridana are similar in growth patterns in media with various sources of carbon, but different in media with different sources of nitrogen. The production of the three fungal species is significantly higher in medium containing 2.66% glucose than in medium with 2.66% sucrose. The addition of 0.1% monossacarides to media containing 2.66% sucrose did not significantly increase biomass production.

Simple, inexpensive media for mass production of three entomophthoralean fungi

The entomophthoralean fungi Batkoa sp., Furia sp. and Neozygites floridana have been suggested for biocontrol of insect pests: the first two for control of spittlebug pests of pasture and sugarcane, and the third for mites of agricultural importance. To develop these agents as biopesticides and bioacaricides, it is important to have available culture media that maximize production at low cost. The research reported here evaluates, in different combinations and concentrations, the effect of four complex sources of nitrogen on production of mycelium or hyphal bodies in liquid media of all three species. Yeast extract allowed the highest production of Batkoa sp., with a concentration of 0.5% being the most suitable for vegetative (mycelial) growth. The combination of 0.33% each of yeast extract + beef extract + skim milk allowed the highest production of Furia sp. Mycelium. The combination of yeast extract + skim milk (0.5% of each) allowed the second highest production of Furia sp., and was the most suitable for mass production due to the lower cost. The combination of 1 %each of yeast extract + peptone + skim milk was the most suitable for production of N. floridana hyphal bodies.

Survey of Phaeomoniella chlamydospora in vineyard weeds

A doença de Petri é grave, complexa e de difícil controle em videiras no mundo. O principal agente causal desta doença é o fungo Phaeomoniella chlamydospora. Este fungo ocorre também na planta daninha de vinhedo Convolvulus arvensis. No Brasil, este fungo foi encontrado somente em videiras. Assim, o objetivo do presente estudo foi efetuar um levantamento fitossociológico de plantas daninhas em uma área com diferentes cavalos de videiras, em um campo de produção de mudas, em uma área experimental com videira e em diferentes áreas com plantio comercial de videira e verificar quais espécies poderiam estar hospedando o fungo P. chlamydospora. Para o levantamento fitossociológico das plantas daninhas, lançava-se um quadrado ao acaso, por dez vezes, no local, contando, identificando Vergaças, P.S.R.; Ferreira, A.B.M.; Franco, D.A.S.; Leite, L.G.; Campos, W.N.; Harakava, R.; Bueno, C.J. Levantamento de Phaeomoniella chlamydospora em plantas daninhas de vinhedo. Summa Phytopathologica, v.44, n.3, p.218-222, 2018. e amostrando todas as espécies. Para verificar as espécies hospedeiras do fungo, realizou-se isolamento do tecido vascular das plantas em meios de cultura e extração de DNA do mesmo tecido vegetal seguido de PCR com primers específicos do fungo do gene do fator de elongação (Pchlamy-EF-F 5’-CTCATTATCACATTTTGCTGC-3’ e Pchlamy-EF-R 5’-GAGAACAGTCAGTGATGAGC-3’). Em todo o levantamento, foram detectadas 46 espécies de plantas daninhas em 17 famílias, destacando-se as famílias Asteraceae e Poaceae com o maior número de espécies cada. Não foi detectado de maneira convencional e nem molecularmente o fungo P. chlamydospora infectando plantas daninhas, ressaltando a ocorrência da doença de Petri apenas em videiras.