DISTRIBUTION OF Meloidogyne enterolobii IN GUAVA ORCHARDS IN THE STATE OF CEARÁ, BRAZIL

ABSTRACT Among the factors negatively impacting guava (Psidium guajava) crop in Brazil, one of the most important is the root-knot nematode, Meloidogyne enterolobii, which may cause considerable yield losses and even the cessation of guava cultivation in some areas. In addition to affecting guava, the pathogen has been reported as a parasite in various other crops, among them both oleraceous and ornamental crops, as well as in spontaneous vegetation. The aim of this study was to verify the occurrence of M. enterolobii in plants collected in guava orchards in different counties of Ceará state, identified through electrophoresis with the isoenzyme esterase, and to observe its infecting behavior into Meloidogyne differentiating plants. Fifty root samples from guava, tasselflower (Emilia fosbergii), and jurubeba (Solanum paniculatum), were collected in 13 counties from eight micro-regions in the state of Ceará. In all analyzed samples, only esterase phenotype M2 (Rm: 0.6; 0.9), characteristic of M. enterolobii, was detected, showing that the nematode is widespread in orchards throughout the state, where is affecting these fruit tree, and that it is also able to parasitizing plants of the spontaneous vegetation. Based on the results, this nematode currently constitutes a serious threat to guava plantations in Ceará, and effective control mechanisms are crucial to prevent the spread of this pathogen to other, still unaffected, areas.

摘要 巴西番石榴（Psidium guajava）种植面临诸多负面影响因素，其中最为重要的之一为根结线虫（Meloidogyne enterolobii），该线虫可造成显著产量损失，甚至导致部分地区终止番石榴种植。除侵染番石榴外，该病原线虫还被报道可寄生多种其他作物，涵盖蔬菜类与观赏类作物，同时亦可侵染野生植被。本研究旨在通过酯酶同工酶电泳技术，对塞阿拉州（Ceará）不同县域番石榴果园采集的植物样本中该线虫的发生情况进行验证，并观察其在根结线虫鉴别寄主上的侵染行为。研究人员从塞阿拉州8个微区的13个县域内，采集了番石榴、一点红（Emilia fosbergii）及假烟叶树（Solanum paniculatum）的共50份根组织样本。在所有分析样本中，仅检测到了该线虫特有的酯酶表型M2（相对迁移率Rm: 0.6; 0.9），结果表明该线虫在全州各果园中广泛分布，已对这些果树造成危害，同时亦可寄生野生植被植株。基于本研究结果，该线虫目前已对塞阿拉州的番石榴种植园构成严重威胁，亟需建立有效的防控机制，以阻止该病原线虫扩散至尚未受侵染的其他区域。