Determining the propagule size required for Meloidogyne species to establish in managed and native soil in New Zealand

New Zealand a geographically isolated country has a unique ecosystem and economy mainly dependant on primary industries Productive and native systems face the ongoing threat of invasive pests The risk from potential pathways for new species including nematodes entering New Zealand is being investigated However there is little knowledge on the nematode inoculum size required for invasion of plant roots and thus establishment of a population in a new area or habitat The present research focused on determining the minimum number of nematode eggs required for invasion into white clover (Trifolium repens) roots commonly found in mixed pasture swards The most economically damaging plant parasitic nematode group worldwide root knot nematodes (Meloidogyne spp) was used for this study Experiments were set up for three species of root knot nematodes already present in New Zealand with five rates of eggs 0 5 10 50 or 100 inoculated into soil from managed or native grasslands The study revealed that five eggs of root knot nematode of all three species are enough for root invasion It was concluded that the invasion of one exotic mature female root knot nematode could be sufficient to establish a new population and pose a threat to the New Zealand ecosystem