Gerbera (Gerbera jamesonii Bolus and Hook,) is an ornamental Asteraceae of great commercial value, and pests can affect adversely its cultivation. More than 20 species of arthropods cause economic damage on gerbera, among them the two spotted mite, Tetranychus urticae Koch, 1836 (Acari: Tetranychidae), considered a key pest for this and other ornamental plants. In this work, some life-cycle aspects of T. urticae on gerbera, considered important for the knowledge of its population dynamics and for pest management programs, were studied. Mites were reared on 3-cm diameter arenas of gerbera leaf discs maintained on distilled water in Petri dishes, under laboratory conditions of 25 °C, 70 ± 10% RU and 14-hour photophase, with only one egg left per arena, in a total of 262 arenas. Egg viability was 96.5% and 97.1% for unmated and mated females, respectively. Unmated females originated larvae which lived for 3.2 days and the stages of protonymph and deutonymph, 1.9 and 1.6 days, respectively; those from mated females lived 3.5 days and for protonymphs and deutonymphs, 2.0 and 1.6 days, respectively. Except for the duration of one generation (T), with similar values, 18.6 and 19.7 days, respectively for unmated and mated females, the net reproductive rate of increase (R 0 ), the innate capacity to increase in number (r m ) and the finite rate of growth (λ) were different for mated and unmated females, respectively 11.5 and 24.6 for R 0; 0.12 and 0.17 for r m and 1.13 and 1.19 for λ.Keywords: Gerbera, biology, fertility life table, two-spotted spider mite. Biologia de Tetranychus urticae (Acari: Tetranychidae) emGerbera jamesonii Bolus and Hook (Asteraceae) ResumoA gérbera, Gerbera jamesonii Bolus and Hook, é uma planta ornamental pertencente à família Asteraceae de grande valor comercial. Dentre os vários fatores que podem afetar adversamente o seu cultivo se encontram as pragas. Mais de 20 espécies de artrópodes causam danos econômicos em gérbera, entre elas encontra-se o ácaro-rajado, Tetranychus urticae Koch, 1836 (Acari: Tetranychidae), considerado praga-chave dessa e de outras plantas ornamentais. O presente trabalho teve por objetivo estudar alguns aspectos do ciclo biológico de T. urticae em gérbera considerados importantes para o conhecimento da dinâmica populacional da espécie e para os programas de manejo de pragas. Os ácaros foram criados em arenas constituídas de discos de folhas de gérbera de 3 cm de diâmetro, sobre água destilada, colocados em placas de Petri, em condições de laboratório, a 25 °C, 70 ± 10% de U.R. e 14 horas de fotofase, deixando-se um ovo por arena, perfazendo um total de 262 arenas. A viabilidade dos ovos foi de 96,5 e 97,1% para fêmeas não acasaladas e acasaladas, respectivamente. As larvas provenientes de fêmeas não acasaladas tiveram duração de 3,2 dias e os estágios de protoninfa e deutoninfa foram de 1,9 e 1,6 dias, respectivamente. Já para fêmeas acasaladas a fase de larva teve uma duração de 3,5 dias, a de protoninfa e deutoninfa 2,0 e 1,6 dias, respectivamente. À exceção...
SUMMARYThe integral transform method is used to compute numerically the development of the velocity profile in the hydrodynamic entrance region for laminar flow inside a parallel plate channel. The results have user-prescribed accuracy and can be used to test other numerical methods.
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