The Probable Spreading and Risk Assessment of the Corn Cyst Nematodes Heterodera zeae and Punctodera chalcoensis on Maize in Belgium and the Netherlands

The corn cyst nematode Heterodera zeae [1], was first detected on the roots of maize collected from Rajasthan, India [1-3]. The pest has subsequently been reported to be present in Pakistan [35], Thailand [2,6], Egypt [7], Greece [8]. Portugal [9] and Virginia and Maryland in the USA [2,10,11] Heterodera zeae is restricted to warmer tropical and sub-tropical areas. And its distribution can be seen in Figure 1a. The corn cyst nematode is a sedentary semiendoparasite feeding on plant roots and has been associated with significant yield losses of between 21 and 73% in infected maize [12]. Above ground symptoms are often characterized by isolated patches of unhealthy plants that are stunted and pale colored [13]. The damage caused by the pest is more profound under hot and dry conditions [14]. The nematode colonizes the roots of its host, producing tan colored, lemon shaped cysts that are visible on the roots of infected plants [15].