A survey was carried out to determine the distribution of Tylenchulus semipenetrans in the most important citrus production region of Spain. A total of 230 samples from 150 geographic points were processed and analyzed. The samples included the most representative types of soil of the region. Thirty-six biotic and abiotic parameters were examined in relation to abundance of females and juveniles of T semipenetrans. Results indicate that the abundance of T. semipenetrans is not related to such parameters, nor the ecological structure that is defined by them in the crop. A gradient of geographic variation of T. semipenetrans was observed that was useful to characterize its distribution pattern. This study is considered a first step in the epidemiologic evaluation of the nematode in the region.
