Comparative effects of entomopathogenic fungi and nematodes and bacterial supernatants against rice white tip nematode

Abstract The rice white tip nematode, Aphelenchoides besseyi, is the primarily important seed-borne pest of rice and was first recorded in Turkey in 1995. These biological agents, such as an entomopathogenic fungus (EPF), entomopathogenic nematodes (EPN), and bacterial supernatants, have been used against other plant parasitic nematodes but as far as not against A. besseyi. Accordingly, the EPF species, Purpureocillium lilacinum, and the four EPN species, Heterorhabditis bacteriophora, Steinernema carpocapsae, S. glaseri, and S. feltiae, and the supernatant of the two bacterial symbionts, Photorhabdus luminescens and Xenorhabdus bovienii, were used against A. besseyi. In addition, infected Galleria mellonella cadavers with S. feltiae were evaluated as a biological agent to the white tip nematode. The percentage of observed white tip symptoms, decrease in kernel numbers in the panicles, and decrease in panicle weight were evaluated. Evaluation of these parameters showed that X. bovienii supernatant, S. feltiae infective juveniles, and P. lilacinum at 108 conidia ml−1 consistently suppressed the A. besseyi population

Diversity and distribution of entomopathogenic nematodes (Rhabditida : Steinernematidae and Heterorhabditidae) in Turkey

The diversity and distribution of entomopathogenic nematodes in the families Steiner-nematidae and Heterorhabditidae were assessed throughout an extensive soil survey in Turkey during 1999 and 2000. Entomopathogenic nematodes were recovered from six out of seven regions sampled, with 22 positive sites (2%) out of 1080 sites sampled. A single nematode isolate was recovered at each of the positive sites, of which 15 were steinernematid isolates and seven were heterorhabditid isolates representing a total of four species. Based on morphometric and molecular data, the nematode species were identified as Heterorhabditis bacteriophora, Steinernema feltiae, S. affine, and Steinernema n. sp. The most common species was S. feltiae, which was isolated from 10 sites in six regions, followed by H. bacteriophora from seven sites in five regions, S. affine from four sites in two regions, and Steinernema n. sp. from one site. Heterorhabditis bacteriophora and S. feltiae have been found in many parts of the world, whereas S. affine, so far, has only been recovered in Europe until our survey. Steinernema affine was isolated from the European (Marmara) as well as the Asiatic region ( Middle Anatolia) of Turkey. A new undescribed Steinernema sp. was isolated from the most eastern region ( East Anatolia) of Turkey. Soils of the positive sites were classified as sandy, sandy loam, or loam ( 68.2%) and sandy - clay - loam or clay loam (31.8%) and the pH ranged from 5.6 to 7.9. The habitats from which the entomopathogenic nematodes were isolated were broadly classified as disturbed (59.1%), which included agricultural fields and poplar planted for lumber and wind breaks, and undisturbed (40.9%), which included pine forest, grassland, marsh and reed sites. Steinernema feltiae, S. affine, and H. bacteriophora were recovered from both disturbed and undisturbed habitats. The new Steinernema sp. was recovered from grassland. Our survey showed that these nematodes occur widely throughout Turkey, but at a frequency below that reported for other parts of the world