Field persistence of Bacillus thuringiensis on maize leaves (Zea mays L.)

Brazilian Journal of Microbiology

Marinéia De Lara Haddad¹  Ricardo Antonio Polanczyk¹  Sergio Batista Alves¹  Marcelo De Oliveira Garcia¹ 

[1] ,Universidade de São Paulo Escola Superior de Agricultura Luiz de Queiroz Departamento de Entomologia, Fitopatologia e Zoologia AgrícolaPiracicaba SP ,Brasil

关键词: entomopathogen;    Dipel;    maize leaves;    Bacillus thuringiensis;    field persistence;    entomopatógeno;    Dipel;    folha de milho;    persistência no campo;    Bacillus thuringiensis;   

DOI  :  10.1590/S1517-83822005000400001

来源: SciELO

【 摘 要 】

The persistence slope of Bacillus thuringiensis (Bt) based products in the field is an important parameter to evaluate their efficacy. The half-life, estimated based on persistence slope parameters, is one of the most effective tools to select microbial pesticides. The aim of this research was to study the relationship between viability loss of Bt spores on maize leaves and their concentration, comparing it with field persistence. The experimental design was split-plot on time, composed by maize plants, in which three concentrations (half, normal and double doses) of a Dipel commercial formulation were applied. In each plot three leaves in the upper part of three plants where randomly selected. Samples of these leaves were collected 3 to 72 hours after treatment, to count the number of viable spores in two foliar dishes with 1 cm in diameter. The field persistence was determined using an exponential model, linearized by a logarithmic transformation of viable spores number in time. Using the log linear method of confidence intervals, there were no significantly differences (P = 0.05) in half-lifes: 18.2 hours for half-dose, 16.5 hours for normal dose and 13.6 hours for double dose. Assuming a fictitious index of insect consumption equal to one, the effective doses according to concentrations were calculated. It was verified that 77%, 78% and 80.5% of the effective doses (viable spores) remained on the leaf surface after the first day of treatment, respectively.

【 授权许可】

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