Heat treatment by microwaves irradiation: a possible solution for sanitizing nematode infected wood

The Food and Agriculture Organization of the United Nations (FAO) has issued (March 2002) a report on: International standards for application of phytosanitary measures to reduce the risk of introduction and for spread of quarantine pests associated with wood packaging material in use in international trade. The pine wood nematode Bursaphelenchus xylophilus, the causal agent of pine wilt disease, is listed among the nematode pests regulated by the European Union. At present, the control measures approved for the elimination of raw wood organisms are heat treatment (HT) and methyl bromide fumigation (MB). Among other wood disinfestation means proposed for approval by FAO, there is microwave irradiation thermal treatment (MW). Treatment by this technique involves exposure to microwave irradiation in shielded chambers. The potential and efficacy of such a procedure were tested for the eradication of Bursaphelenchus spp. and other saprophytic nematodes frequently associated with wood samples of conifer and broadleaf trees. In this experiment, B. mucronatus was used as target species instead of B. xylophilus, because of the great biological similarity of these two species and to avoid the risk associated with transportation and handling of wood infested by this dangerous quarantine nematode, so far not found in Italy. Powers of 3-13.5 Kw were used with exposure times of 90-720 seconds. The temperature inside the wood ranged from 43 deg C to 141 deg C. The microwave device was very effective in producing temperatures lethal for all wood nematodes La FAO nel marzo 2002 ha emesso una normativa che descrive le misure fitosanitarie da adottare per ridurre il rischio di introduzione e/o di diffusione di organismi nocivi da quarantena associati ai materiali da imballaggio in legno grezzo, utilizzati nel commercio internazionale. Le misure attualmente approvate prevedono trattamenti termici (HT) e fumigazioni con bromuro di metile (MB). Tra gli organismi nocivi più significativi associati al legname, oltre a numerosi insetti xilofagi, viene citato anche Bursaphelenchus xylophilus, nematode afelenchide da quarantena, noto come il nematode del legno del pino, agente del deperimento rapido dei pini, al momento non segnalato in Italia. Nell'elenco stilato dalla FAO, tra le misure in attesa di approvazione da adottare per la disinfestazione del legno da imballaggio, è incluso il trattamento termico mediante irraggiamento a microonde, processo che si realizza in apposite cam