Efeito da liberação aumentativa no campo de Pseudophilothrips ichini no desenvolvimento de Schinus terebinthifolius

Abstract

Experimentos de campo foram conduzidos com Pseudophilothrips ichini (Hood), 1949 (Thysanoptera: Tubulifera: Phlaeothripidae) por dois anos, para determinar o dano na produção de brotação na aroeira, Schinus terebinthifolius Raddi (Anacardiaceae). O primeiro experimento com 40 mudas de aroeira eqüiâneas foi executado entre agosto de 2001 e maio de 2002. O tratamento-testemunha (n = 20) foi pulverizado com solução aquosa (1% i.a.) do inseticida Deltametrina 25CE; o outro recebeu infestações forçadas de 400 espécimes, adultos e ninfas. O segundo experimento, de julho de 2002 a maio de 2003, foi realizado com 60 mudas, submetidas a três tratamentos. Vinte plantas foram infestadas artificialmente com 800 espécimes, adultos e ninfas (n = 40 por planta). No segundo grupo de mudas (n = 20), ocorreu infestação natural. O terceiro grupo (n = 20) foi pulverizado a cada 15 dias para excluir P. ichini. A perda de biomassa nos experimentos foi de 20% no primeiro e 62% no segundo; a infestação natural causou perda de 22%. Os resultados mostraram que P. ichini é um potencial agente de controle da aroeira.

A manipulative field experiment replicated over a 2-year period was conducted with Pseudophilothrips ichini (Hood), 1949 (Thysanoptera: Tubulifera: Phlaeothripidae) in order to determinate damage on shoot production of its host Brazilian peppertree, Schinus terebinthifolius Raddi (Anacardiaceae). In the first trial, conducted from August 2001 to May 2002, 40 Brazilian peppertree seedlings of the same age, class and size were planted and randomly assigned by two treatment groups. Half of the plants (n=20) were sprayed with 1% ai of Deltamethrin 25CE, the other half was manually infested with 400 thrips, adults and larvae (n=20 per plant). 60 Brazilian peppertree seedlings subjected to three treatments constituted the second experiment, conducted from July 2002 to May 2003 at the same location. Twenty plants were artificially infested with 800 thrips adults and larvae (n=40 per plant). A second group of 20 seedlings suffered natural infestation. The third group of 20 seedlings was sprayed with insecticide each 15 days to exclude P. ichini. In the first experiment biomass of Brazilian peppertree was reduced by 20% in plants artificially infested with P. ichini whereas a 62% reduction rate was observed in the second experiment. Plants naturally infested with the thrips in the second experiment exhibited a 22% loss in biomass in relation to the control group. The experiment demonstrated P. ichini as a potential biological control agent of Brazilian peppertree.