| Â | The root knot nematodes are nowadays one of the biggest problems caused by plant parasitic nematodes in the greenhouse horticulture all around the world. The use of chemical pesticides for reducing this problem has become common, although with high environmental impact and risks to human health. For this reason, the chemical pesticide application has now more restrictions and pesticide users are limited in choices available to combat plant diseases. It is essential the availability of alternative and effective control measures with low secundary effects. There is therefore a growing interest in biological control and particularly in the exploitation of fungi to control pests, diseases and weeds which is demonstrated by the number of fungi based products already on the market and also in development (Butt, 2001). Fungi types
There are a large number of fungi species associated with nematodes, but only a small number of these have been exploited for the development of biological control agents.
These can be divided into three categories according to their action mode: |  | |  | Â
a) Nematode-trapping fungi: hyphae networks, branches, buttons, stickers, rings or non-constrictor rings (eg Arthrobotrys irregularis, Dactylella spp. Monacrosporium spp.)
ii) Endoparasitic fungi: adhesives spores that attach to the nematode cuticle and penetrate it, colonizing the host and or zoosporic spores that need to be ingested to colonize the host (Drechmeria coniospora, Catenary anguillulae and Hirsutella rhossiliensis)
iii) Parasitic fungi attacking sedentary stages of nematodes: fungi that parasites eggs from sedentary females of plant parasitic nematodes interrupting the reproductive cycle (Pochonia chlamydosporia, Paecilomyces lilacinus)
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