Cactodera cacti (Nematoda: Heteroderidae) : ocorrência natural em mandacaru (Cereus jamacaru DC.) no Ceará e investigação de hospedeiras em cactáceas e hortaliças

Abstract

In July 2016, the nematode Cactodera cacti was found naturally associated with the roots of adult plants of Cereus jamacaru D.C., known locally as mandacaru, in a predominantly vegetable-growing area of Fortaleza-CE. This study represents the first report of this nematode in the State of Ceará, Brazil, and describes initial studies with the pathogen. The identification of this nematode was realized through morphological and molecular studies at the Agronômica Consulting Laboratory for Phytosanitary Diagnosis (Porto Alegre-RS). Considering the global importance of this phytonematode to cactaceae, and the threat that the pathogen may pose to commercially important species in the state, an investigation was carried out of its hosts, including ornamental, forage and fruit cacti, as well as soybean and vegetables. Eggs taken from cysts of C. cacti in roots of the mandacaru and from infested soil were used as the nematode inoculum. Aliquots of the suspension containing from 1,800 to 3,200 eggs were inoculated into soil with seedlings of the ornamental cacti Echinopsis multiplex, Nopalea cochenillifera, Mammillaria prolifera, and Cereus jamacaru; of the fruit cactus (Hylocereus undatus), and forage palm (Opuntia ficus-indica); as well as the tomato (Solanum lycopersicum L.) 'Santa Cruz', coriander (Coriandrum sativum L.) 'Verdão', the pepper (Capsicum annuum L.) 'All Big', Arugula (Euca sativa Miller) 'Antonela', eggplant (Solanum melogena L.) 'Roxa', cucumber (Cucumis sativus L.) 'Verde Comprido', cabbage (Brassica capitata L.) 'Chato de Quintal', kale (Brassica oleracea L.) 'Georgia Butter' and the soybean (Glycines max (L.) Merrill) 'NS7209', in greenhouse (31 + 3ºC). The vegetables and soybean were included in the trial as the phytonematode had been found in the vicinity of vegetable crops. After 40 to 60 days, the plants were removed from the pots, and the roots analysed with a stereo microscope. The examination revealed nematode parasitism in E. multiplex, M. prolifera, N. cochenillifera, mandacaru, pitaia and forage palm, as the presence of females and cysts was found in the root system of all the above plants. No infection was seen in the roots of the vegetables or soybean under test. It was concluded from the results that C. cacti, preferably infests plants of family Cactaceae, and could become a risk to the production of Cactaceae in the state of Ceará.