Morphological and chemical characteristics of onion plants associadas a resistencia ao tripes da cebola

Thrips tabaci Lindeman is the main pest of onion crops, and chemical control is the main method adopted by farmers. Alternative control methods should be prioritised to reduce the amount of insecticides used. Resistant cultivars are one efficient way to control thrips in the field. Our aim was to assess the influence of morphological and chemical characteristics of seven onion cultivars and their resistance to T. tabaci. The number of thrips and the morphological and chemical characteristics of the plants were assessed. Among the evaluated cultivars, Alfa Sao Francisco RT, BR 29 and Sirius showed resistance to T. tabaci, as indicated by the lower number of thrips observed during the cycle (64, 87, and 74 thrips, respectively). Morphological and chemical characteristics were associated with onion's resistance to T. tabaci. For the cultivar Alfa Sao Francisco RT, a wider central angle (16.4°), a thinner cuticle, a larger amount of epicuticular waxes, and stomata on the surface of leaves accounted for resistance. For the cultivars BR 29 and Sirius, the resistance was likely due to the presence of resistance-conferring substances or high amounts of some component in the chemical composition of plants. Keywords: Thrips tabaci, Thysanoptera, Thripidae, onion, plant resistance to insects. Thrips tabaci Lindeman e a principal praga da cultura da cebola e o controle quimico e o principal metodo adotado pelos agricultores. Metodos alternativos de controle devem ser priorizados, visando diminuir a quantidade de inseticidas utilizada. Cultivares resistentes representam um metodo eficiente de controle de tripes no campo. Nosso objetivo foi verificar a influencia de caracteristicas morfologicas e quimicas de sete cultivares de cebola conferindo resistencia a T. tabaci. O numero de tripes, caracteristicas morfologicas e quimicas das plantas foram avaliadas. Dentre as cultivares avaliadas, Alfa Sao Francisco RT, BR 29 e Sirius mostraram-se resistentes a T. tabaci, uma vez que apresentaram um baixo numero de tripes observados durante o ciclo (64, 87 e 74 tripes respectivamente). Caracteristicas morfologicas e quimicas estao associadas a resistencia de plantas de cebola a T. tabaci. Para a cultivar Alfa Sao Francisco RT, um maior angulo central (16,4°), uma menor espessura de cuticula, e uma maior concentracao de ceras epicuticulares e estomatos na superficie das folhas conferem resistencia. Para as cultivares BR 29 e Sirius, a resistencia provavelmente esta relacionada a p