Host weed species range of Meloidogyne ethiopica whitehead (Tylenchida: Meloidogynidae) found in Brazil

Abstract

Meloidogyne ethiopica is considered to be one of the most economically important emerging nematode species, reported to cause crop losses to several hosts worldwide. The significance of this species is due to its high virulence and degree of polyphagia, in addition to persisting on weed hosts within agricultural fields. This study evaluated the host status of 36 different weed species, confirming the polyphagia habit of M. ethiopica and indicating which plant species may be alternative hosts for this plant nematode. Weed species were inoculated with 5000 eggs and second-stage juveniles (J2) of M. ethiopica, with gall index (GI), nematode/g root (Nem/g), and reproduction factor (RF) value determined following 60 days post inoculation. The data obtained indicate that many weed species may be excellent hosts for M. ethiopica. Plants deemed susceptible (RF ≥ 1.0) were: Acanthospermum australe, Amaranthus deflexus, A. hybridus, A. spinosus, A. viridis, Bidens pilosa, B. subalternans, Cardiospermum halicacabum, Commelina benghalensis, Cynodon dactylon, Euphorbia heterophylla, Galinsoga parviflora, Ipomoea grandifolia, I. nil, I. purpurea, Leonurus sibiricus, Nicandra physaloides, Oxalis corniculata, Portulaca oleracea, Raphanus raphanistrum, Sida rhombifolia, Solanum americanum, S. pseudocapsicum, S. sisymbriifolium, Sonchus oleraceus and Talinum paniculatum, representing 72.2% of the species assessed. The species Conyza bonariensis, Cyperus rotundus, Digitaria horizontalis, D. insularis, Echinochloa colonum, Eleusine indica, Lolium multiflorum, Polygonum hydropiperoides, Rhynchelytrum repens and Senecio brasiliensis were resistant to M. ethiopica (RF < 1.0). Based on the new host records presented, it is vital that control of weed species within agricultural fields are considered as part of effective management of M. ethiopica.