Investigations on entomopathogenic nematodes as biological control agents

The overall objective in this thesis was to investigate the ecology, biological control potential and storage of Turkish isolates of entomopathogenic nematodes. Objective 1 was to understand the survival strategy of the nematode/bacterial complex in an insect cadaver when the cadaver was attacked by insect scavengers. For objective 1, because earlier studies related with Ant Deterrent Factor (ADF) were only done with ant species, in this study other insect scavengers were investigated to determine whether they were also deterred by ADF. Bacteria and cadaver experiments showed that ADF had a strong negative effect on all tested scavengers. It was also determined that ADF was an extracellular substance(s) that maintained its activity at high temperatures and was stable for a long time.For objective 2, the biological control potential of six native entomopathogenic nematode isolates was tested against S. exigua larvae. In laboratory studies, the nematode, S. carpocapsae, was the most effective species against the larvae causing 100% mortality in 20 ml plastic cups and 77% mortality in 30 x 30 cm containers with turfgrass.For objective 3, inexpensive tetrapak boxes used for food storage were found to be excellent alternative storage containers for maintaining these nematodes. Nematode survival over 11 months was comparable to the expensive cell culture flasks. Consequently it was determined that these tetrapak boxes can serve as alternatives to the cell culture flasks to store nematodes for biological control programs.Key words: Entomopathogenic nematodes, Steinernema, Heterorhabditis, ADF, Tetrapak, Biological control, Photorhabdus, Xenorhabdus