Internal biosecurity - a realistic objective for plant nematodes?

Nematodes and insects share common features of taxonomic and ecological biodiversity, with different species exploiting a wide range of environmental niches. However, plant-feeding nematodes are usually very small, and require a moisture phase for activity. This allows very limited active dispersal in soil, but survival mechanisms allow the ability for passive dispersal in transported soil, plant material, flowing water and sometimes wind-blown soil. The range of plant hosts differs widely among nematode species. The indigenous New Zealand fauna has not adapted to exotic agricultural plants. Agricultural crops are exposed to a limited biodiversity of introduced pest nematodes, with many of the nematodes having only a limited distribution within New Zealand. This reduced nematode diversity compared with comparable habitats in the northern hemisphere contributes to competitive advantages for plant-based industries. As many crops are strongly regionalised, deliberate grower application of biosecurity practices could sustain unique advantages. The possibilities in New Zealand are illustrated using a variety of crop examples.