Bioecological studies of Neozygites floridana (Entomophthorales: Neozygiteceae), the fungal pathogen of Tetranychus evansi (Acari: Tetranychidae) / Estudos bioecológicos de Neozygites floridana (Entomophthorales: Neozygitaceae) fungo patogênico de Tetranychus evansi (Acari: Tetranychidae)

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

The tomato red spider mite, Tetranychus evansi Baker and Pritchard is an important exotic pest of Solanaceae in Europe and Africa. It is suggested that this mite could have originated from South America, a region where it is not considered as an important pest. An important natural enemy of T. evansi in Brazil is the fungus Neozygites floridana Weiser and Muma that is characterized by high virulence, restricted host range and fastidious in vitro growth. The taxonomy of Neozygites species is still uncertain given that some species cannot be distinguished by morphological characteristics. Molecular studies are usually necessary for discrimination of species and isolates of Neozygites pathogenic to tetranychid mites. Isolates of N. floridana from T. urticae have low virulence towards T. evansi and vice versa. Through partial sequencing of the 18S ribosomal DNA region of N. floridana, it was verified that the isolate of T. evansi (LQ2) had 98% similarity to the isolate of T. urticae (LQ3), but these two isolates had high divergence from other isolates pathogenic to tetranychid mites. For example, the similarity between two isolates collected on T. urticae, LQ3 and ARSEF662, was only 90%, indicating that the fungi identified as N. floridana may be a species complex. Although N. floridana is the principal natural enemy associated with T. evansi in most regions surveyed in Brazil up to date, the role of this pathogen in regulation of T. evansi population has not been determined. This study monitored the impact of the epizootics of the pathogen on populations of T. evansi in experiments both in the field and protected environments in four planting dates on nightshade and tomato with and without pesticide applications. The density of T. evansi was correlated with the prevalence of the fungus and the environmental conditions. The only natural enemy observed was N. floridana and the data revealed that is the fungus is an important factor in the regulation of T. evansi populations in tomato, especially in protected environment. Its introduction to continents where this pest was recently introduced may contribute to the reduction of its impact in these regions.

ASSUNTO(S)

tomato. controle biológico (fitossanidade) population dynamics solanaceae biological control (phytosanity) solanaceae dinâmica de populações mites tomate. biologia molecular molecular biology Ácaros fungi fungos

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