Seletividade de defensivos agrícolas ao fungo entomopatogênico Beauveria bassiana

Abstract

-The relative toxicity of the insecticides organophosphates methyl-chlorpyrifos, disulfoton, ethion, methyl-parathion, the organochlorinate endosulfan and the mixture of the fungicide triadimenol and the insecticide disulfoton and the sterol demethylation inhibiter fungicide (triadimenol and tebuconazole) to the fungus Beauveria bassiana (Balsamo) Vuillemin was evaluated. Concentrations which inhibited radial mycelium growth (99%) of B. bassiana were 0.42; 1.69; 6.53; 14.42; 31.75; 7,028.96; 10,326.76 e 763,959.86 mg i.a/ml of tebuconazole, methyl-parathion, triadimenol, triadimenol + disulfoton, methyl-chlorpyrifos, ethion, endosulfan and disulfoton, respectively. The effects of these products were evaluated based on percentage of inhibition of radial mycelium growth of B. bassiana on potato dextrose-agar impregnated with them, after seven days. Tebuconazole, methyl-parathion and methyl-chlorpyrifos were highly toxic to B. bassiana; endosulfan and triadimenol + disulfoton were moderated toxic; while triadimenol, ethion, and disulfoton were selective to this fungi.KEY WORDS: Toxicity, natural enemy, coffee berry borer, biological control RESUMO -A toxicidade relativa dos inseticidas organofosforados clorpirifós-metílico, dissulfotom, etiom, paratiom-metílico, do organoclorado endosulfam, da mistura do fungicida triadimenol e do inseticida dissulfotom e dos fungicidas inibidores da demetilação de esteróis triadimenol e tebuconazole ao fungo Beauveria bassiana (Balsamo) Vuillemin foi estudada em laboratório. As concentrações dos pesticidas que inibiram 99% do crescimento micelial desse fungo, em miligramas de ingrediente ativo por ml foram: tebuconazole = 0,42; paration-metílico = 1,69; triadimenol = 6,53; triadimenol + dissulfotom = 14,42; clorpirifós-metílico = 31,75; etiom = 7.028,96; endosulfam = 10.326,76 e dissulfotom = 763.959,86. As equações de regressão da inibição do crescimento micelial (%), em função da concentração obtida por ensaio in vitro em meio batata-destrose-ágar (BDA) impregnado com os ingredientes ativos desses compostos, foram usadas para se estimar a seletividade das concentrações prescritas para cafezais, pelos seus respectivos fabricantes. Tebuconazole, paratiommetílico e clorpirifós-metílico foram altamente tóxicos ao fungo B. bassiana; endosulfam e triadimenol + dissulfotom apresentaram seletividade moderada e triadimenol, etiom e dissulfotom foram seletivos para esse fungo. PALAVRAS-CHAVE: Toxicidade, inimigo natural, broca-do-café, controle biológico A broca-do-café Hypothenemus hampei (Ferrari) (Coleoptera: Scolytidae) causa prejuízos quantitativos, como perda de peso dos grãos e queda de frutos, além de qualitativos, como a redução da qualidade do café, alteração no tipo e, às vezes, da bebida (Souza et al. 1981, IBC 1986.Os cafezais apresentam muitas espécies de insetos, ácaros e fungos, algumas das quais são pragas de importância econômica, enquanto a maioria não chega a causar prejuízo, por serem mantidas sob controle por inimigos naturais (Bustillo 1990). O ressurgimen...

Clouding behaviour in surfactant systems

“…Faria et al [269] have reported a green method using cloud point extraction and gas chromatography, for the extraction and determination of disulfoton [diethyl-S-{2-(ethylthio)ethyl}-phosphorodithioate], an insecticide and acaricide [270,271] for controlling the B. Mineiro in coffee cultivation [272,273], from surface water samples. The extraction was carried out in micellar solution of TX-114 with highest extraction efficiency of 91.4% at a concentration of 1.0% (w/v) of TX-114 and a pH range of 4.0-7.0.…”

Compatibility of the fungus Beauveria Bassiana (Bals.) Vuill. (Deuteromycetes) with extracts of neem seeds and leaves and the emulsible oil

“…Endosulfan, an organochlorine, is still the most common treatment against H. hampei, in spite of its fungitoxic effects on Beauveria bassiana (Mourão et al 2003, Oliveira et al 2003, one of the most important, naturally occurring pathogens of coffee berry borer. Continuous utilization of endosulfan may promote the selection of populations that are resistant to the insecticide and to other products of the same chemical group (Brun et al 1989(Brun et al , 1994, as well as cause environmental problems and farmers intoxication.…”

Autochthonous endophytic bacteria from Musa sp. controls Fusarium oxysporum f. sp. cubense under in vitro conditions

“…The "R" software version 3.5 (R Core Team 2015) was used for statistical analysis. The percentage of reduction within each variable was determined by the formula described by Mourão et al (2003): % Reduction = [1 -(Average of Treatment / Average of Control)] * 100.…”