Infestação de Diatraea spp. (LEPIDOPTERA: CRAMBIDAE) em variedades RB (República do Brasil) de cana-de-açúcar

O objetivo deste trabalho foi avaliar o comportamento de variedades RB (Republica do Brasil) de cana-de-acucar em relacao ao ataque de Diatraea spp. Foram utilizados os sistemas de cultivo de sequeiro e irrigado. As variedades estudadas foram: RB72454, RB867515, RB971755, RB951541, RB931003, RB92579, RB863129 e RB93509. Para o cultivo irrigado, incluiu-se a RB98710. As avaliacoes da porcentagem de intensidade de dano interno foram realizadas por ocasiao da colheita, em 15 colmos de cada parcela. Todos os colmos foram abertos no sentido longitudinal, obtendo-se assim a porcentagem de entrenos danificados pelo complexo broca/podridao. As medias foram comparadas pelo teste de Tukey a 5% de probabilidade. No primeiro ano de avaliacao, no cultivo de sequeiro, a variedade RB971755 apresentou maior media de infestacao de Diatraea spp. quando comparada com as demais variedades. No segundo ano a variedade RB931003 foi a mais atacada pela praga e nos dois anos subsequentes as variedades nao diferiram entre si em relacao ao ataque da praga. No cultivo irrigado, em cana planta, a variedade RB867515 apresentou maior infestacao por Diatraea spp. e nos dois anos seguintes nao houve diferencas significativas entre as variedades testadas. Em ambos os sistemas de cultivo, houve um decrescimo na produtividade da cultura durante as avaliacoes anuais. Os valores de % de infestacao nao apresentaram correlacoes significativas com os parâmetros agroindustriais avaliados em ambos os sistemas de cultivo. Infestation OF Diatraea spp. (Lepidoptera: Crambidae) in varieties of sugar cane Abstract The aim of this study was to evaluate the variation of infestation Diatraea spp. in different varietiesRB (Republic of Brazil) of cane sugar in cropping systems for dryland and irrigated four and threeyears, respectively. The varieties studied were as follows: RB72454, RB867515, RB971755, RB951541,RB931003, RB92579, RB863129 and RB93509. For the irrigated system, the variety RB98710 was alsoincluded. Assessments of the percentage of intensity of internal damage were carried out at harvest,in 15 stalks in each plot. All stalks were opened longitudinally, thus obtaining the percentage ofinternodes damaged by the complex borer/rottenness. The results were submitted to analysis ofvariance and means were compared by Tukey test at 5% probability. In the first year of assessment,in rainfed crop, the variety RB971755 showed the highest average of infestation by Diatraea spp.when compared with all other varieties. In the second year the variety RB931003 was the mostattacked by the pest and for the subsequent two years the varieties did not differ in relation topest attack. In the first year, for the irrigated system, the most infested variety was RB867515. In thefollowing two years it was not possible to identify a variety with striking characteristic of preferenceby the sugar cane borer. In both systems, there was a decrease in crop productivity during annualassessment. The values of % infestation showed no significant correlations with the agroindustrialparameters evaluated in the two systems of cultivation.