Efeito de produtos fitossanitários químicos utilizados em alface e crisântemo sobre fungos entomopatogênicos

Abstract

-The effect of eight fungicides and twelve insecticides used in lettuce and chrysanthemum crops, was evaluated on the fungi Beauveria bassiana (Bals.) Vuill., Metarhizium anisopliae (Metsch.) Sorok., Paecilomyces fumosoroseus (Wise) (Holm ex SF Gray) and Verticillium lecanii (Zimmerman) through in vitro tests. The products were added to petri dishes containing culture medium (PDA), according to the concentrations recommended for application in field. After the inoculation of the fungi, the plates were incubate at 25±1°C, 12h fotophase and 70±10% relative humidity. The mean diameter of colonies and the number of conidia produced after a variable period of incubation for each studied fungus were evaluated. The insecticides thiametoxan and imidacloprid were compatible with all the fungi studied. On the other hand, cuprous oxide, iprodione, methyl parathion, tebuconazol, metalaxil, mancozeb, folpet, fenpropathrin and tetraconazol inhibited the growth of the fungi, being classified as toxicant or very toxicant products to the entomopathogens.KEY WORDS: Insecta, microbial control, integrated control, insecticide, fungicide.RESUMO -O efeito de oito fungicidas e doze inseticidas, utilizados nas culturas de alface e crisântemo, foi avaliado in vitro sobre os fungos entomopatogênicos Beauveria bassiana (Bals.) Vuill., Metarhizium anisopliae (Metsch.) Sorok., Paecilomyces fumosoroseus (Wise) (Holm ex SF Gray) e Verticillium lecanii (Zimmerman). Os produtos foram colocados em placas de Petri contendo meio de cultura (BDA), nas concentrações recomendadas para aplicação em campo. Após a inoculação dos fungos, as placas foram incubadas em sala climatizada a 25±1°C, fotofase de 12h e umidade relativa de 70±10%. Foram avaliados o diâmetro médio das colônias e o número de conídios produzidos após um período de incubação variável para cada fungo estudado. Os inseticidas tiametoxam e imidaclopride foram compatíveis com todos os fungos estudados. Por outro lado, óxido cuproso, iprodione, paratiom metílico, tebuconazole, metalaxil, mancozebe, folpete, fenpropatrina e tetraconazole inibiram o crescimento dos fungos, sendo classificados como produtos tóxicos ou muito tóxicos aos entomopatógenos. PALAVRAS-CHAVE: Insecta, controle microbiano, controle integrado, inseticida, fungicida.Existem atualmente no mercado inúmeras substâncias químicas empregadas no controle de pragas e doenças, sendo os inseticidas e fungicidas um grupo numeroso e destacado. Entretanto, as conseqüências da sua utilização não são unicamente positivas. Muitos desses compostos químicos são tóxicos ao homem e animais e, também do ponto de vista ambiental, acarretam diminuição do potencial de controle efetuado por predadores, parasitóides e patógenos. O controle integrado, com a utilização de produtos fitossanitários seletivos em conjunto com fungos entomopatogênicos ou outros agentes de controle biológico, pode ser uma estratégia mais segura e eficiente. Entretanto, alguns produtos fitossanitários podem afetar o crescimento vegetativo, a viabilidade e a coni...

Action of pesticides to Metarhizium anisopliae in soil

“…Analyzing the compatibility between the active ingredients tebuconazol, mancozeb and copper oxychloride and B. bassiana based on the determination of the vegetative growth and reproduction of the fungus, Tamai et al (2002) classified the fungicides as highly toxic to the pathogen. A similar result was reported by Loureiro et al (2002) who observed that the growth of M. anisopliae colonies was inhibited by the same fungicides. Although a toxic action of these products on M. anisopliae in soil was observed in some evaluations of the present study, this effect cannot be considered marked since the pathogen recovered its respiratory activity almost immediately after the decline and the mean production CO 2 total in the treatments with the fungicides did not differ from control.…”

“…However, no toxicity of imidacloprid to M. anisopliae was observed by Loureiro et al (2002), and Neves et al (2001) showed that the product did not inhibit germination, radial growth or fungal reproduction. Nevertheless, according to the last authors, deltametrin presented marked toxicity to M. anisopliae and other entomopathogenic fungi.…”

“…Loureiro et al (2002) reported that M. anisopliae colonies grown in the presence of abamectin showed morphological alterations and reduced production of conidia.…”

“…Several studies have analyzed the effects of pesticides on entomopathogenic fungi in order to determine their compatibility for pest control (Poprawski & Majchrowicz 1995, Neves et al 2001, Loureiro et al 2002. Most of these reports were conducted by adding products to the synthetic culture media used for fungal growth.…”

<b>Population density of <i>Beauveria bassiana</i> in soil under the action of fungicides and native microbial populations

“…In spite of these results, all fungicides were rated as toxic to B. bassiana based on the calculated BI (Table 2). A similar result was obtained by Loureiro, Moino, Arnosti, and Souza (2002) who found that fungicides containing thiophanate-methyl and mancozeb as active ingredients were also classified as very toxic to the CB 66 isolate of B. bassiana. Non-transformed data reported in the table, but analyses were performed after arc-sinetransformation.…”