Aspectos biológicos de Neozygites floridana (Weiser & Muma) (Zygomycetes : Entomophthorales) e dinâmica populacional deTetranychus evansi Baker & Prictchard (Acari : Tetranychidae) e seus inimigos naturais em Solanum americanum Mill

Abstract

Neozygites floridana (Weiser & Muma) (Zygomycetes: Entomophthorales) infects several species of Tetranychidae in different locations around the world. In Brazil, N. floridana was reported in Tetranychus evansi Baker & Pritchard and Tetranychus urticae Koch. Disease caused by this pathogen on tetranychids indicates its potential in biological control programs. In this study was tested the specificity of N. floridana isolates to different species of Tetranychidae, the epizootiology of this fungus in a greenhouse, in semi-field and in the field on T. evansi in Solanum americanum Mill., and evaluated the combination of some biotic and abiotic factors on the formation of resting spores. For all strains studied contamination, infection and mummification was always higher to the species of mites from which the strains were obtained. The main natural enemies of T. evansi were N. floridana and Phytoseiulus longipes Evans. The population increase of tetranychids was always followed by increases in the density of natural enemies. It was found that the population density of natural enemies is strongly influenced by climatic factors and the density of T. evansi. The occurrence of N. floridana appears to be restricted to periods of highest rainfall from May to September. The predator P. longipes had itshighest population density during the dry period of the year, from October to February. The mites with resting spores were only 0.03%, from 13,516 mites evaluated. All mites found with resting spores belonged to the species T. evansi and to isolate LQ4. During the dry season we did not observe N. floridana structures in adult females of T. evansi under conditions of semi-field. S. americanum is a natural host for maintenance of populations of T. evansi and also allows the development of natural enemies such as N. floridana and P. longipes in the field.