Tolerance of sugarcane cultivars to Mahanarva fimbriolata/Tolerancia de cultivares de cana-de-acucar a Mahanarva fimbriolata

Mahanarva fimbriolata (Stal) (Hemiptera: Cercopidae), the sugarcane spittlebug, is one of the most important pests of this crop in Brazil. The magnitude of its damage depends on the pest population, the plants size when they are infested and the cultivar tolerance. The knowledge about those parameters allows the elaboration of the spittlebug management matrix, in which small plants and less tolerant varieties fields are prioritized for sampling and controlling in relation to developed plants and tolerant varieties fields. Therefore, this study aimed to evaluate the response of sugarcane genotypes to M. fimbriolata, so that they can be correctly allocated in the management matrix. Two experiments were carried out under laboratory conditions using a randomized block design with treatments in a factorial arrangement of 2 x 11 (experiment 1) and 2x21 (experiment 2), with six (experiment 1) or five replicates (experiment 2). The first factor included two levels of infestation (infested and noninfested plants with spittlebugs), while the second consisted of the cultivars. Cultivars IACSP01-5503, CTC 9004 and RB925211 were considered tolerant to spittlebug, they did not show significant reductions in aboveground biomass, despite showing symptoms of pest attack, as leaves yellowing, while CV6654 and IACSP01 -3127 were the least tolerant cultivars, showing the highest reduction in aboveground biomass due to M. fimbriolata infestation. Thus, CV6654 and IACSP01-3127 should be prioritized for sampling and control over the others. On average, spittlebug infestations caused 30.9 % of reduction of aboveground biomass. Key words: spittlebugs, plant resistance, Saccharum. A cigarrinha das raizes, Mahanarva fimbriolata (Stal) (Hemiptera: Cercopidae), e urna das mais importantes pragas da cana-deagucar no Brasil. A grandeza de seus danos depende da populaqao, do tamanho da planta ao sofrer o ataque e da tolerancia da cultivar. O conhecimento sobre esses parametros permite a elaboragao da matriz de manejo de cigarrinha das raizes, na qual canaviais de plantas pouco desenvolvidas e cultivares nao tolerantes sao priorizados para amostragem e controle em relagao a canaviais de plantas mais desenvolvidas e variedades tolerantes. Portanto, o objetivo do presente trabalho foi avahar a reagao de cultivares de cana-de-agucar a M. fimbriolata, para que elas possam ser adequadamente locadas na matriz de manejo. Dois experimentos foram conduzidos em condigoes de laboratorio, usando o de