Effects of fertigation on the occurence and damages of Mahanarva fimbriolata (Stål) (Hemiptera: Cercopidae) in sugarcane

Brazil stands out as the world's largest producer of sugarcane and its productivity is closely related to the availability of water and nitrogen during its development and also to the incidence of pest insects. Among the species most harmful to the sugarcane in Brazil, Mahanarva fimbriolata stands out, which has seriously endangered the yields. In this context, the present study aimed to evaluate the effect of the nitrogen fertirrigation on the incidence and damage caused by M. fimbriolata in sugarcane. The experiment was composed of five treatments and four replications in a randomized block design (RBD). The treatments were composed of four doses of N-fertilizer and control (0, 50, 100, 150, 200 kg.ha-1) in drip irrigation system. The parameters evaluated were: number of nymphs in the roots, stalk productivity, sugar content, percentage of sugar, total recoverable sugar and the agricultural contribution margin. It was observed that the fertirrigation increases the productivity of stalks and sugar with the increase of nitrogen fertilization by irrigation. The use of 200 kg.ha-1 of N-fertilizer increased the incidence of M. fimbriolata up to the control and economic damage levels. The biggest financial yield was obtained with the dose of 150 kg.ha-1 of N-fertilizer.

巴西作为全球最大的甘蔗生产国，其甘蔗生产力与生长发育期的水分、氮素供应及害虫发生风险紧密相关。在巴西境内危害甘蔗的优势害虫物种中，带纹脊沫蝉（Mahanarva fimbriolata）最为突出，该虫已严重威胁甘蔗生产的产量安全。在此研究背景下，本试验旨在评估氮素肥灌对甘蔗受M. fimbriolata为害的发生程度与损害程度的影响。本试验采用随机区组设计（Randomized Block Design, RBD），设置5个处理组与4次重复；处理组包含4个氮肥施用量梯度及空白对照组，施用量分别为0、50、100、150、200 kg·ha⁻¹，通过滴灌系统（drip irrigation system）实施施肥作业。本试验测定的指标包括：根部若虫数量、茎秆产量、蔗糖含量、含糖百分比、总可回收糖量及农业边际贡献。结果显示，随灌溉施氮量的提升，茎秆与蔗糖产量均呈上升趋势。当施氮量达到200 kg·ha⁻¹时，M. fimbriolata的发生量升至对照组水平与经济损害阈值。而施氮量为150 kg·ha⁻¹时，可获得最高的农业收益。