Evaluation of xenorhabdus and photorhabdus bacterial secondary metabolites against Tetranychus urticae (Acari:Tetranychidae)

The effectiveness of secondary metabolites produced by symbiotic bacteria, Xenorhabdus szentirmaii, X. nematophila, X. bovienii, X. cabanillasi, Photorhabdus luminescens and P. temperata associated with entomopathogenic nematodes was investigated against different developmental stages of Tetranychus urticae (Acari: Tetranychidae) using cell-free bacterial supernatants in Petri dishes. In addition, the effectiveness of the most virulence bacterial supernatant(s) found in Petri dish experiments was tested on T. urticae in pot experiments. All studies were conducted at 25±1oC temperature, 70±5% relative humidity and a light cycle of 16h in a climate room. The result of the Petri dish experiments showed that the mortality rate of bacterial supernatants on T. urticae egg, larva, protonymph, deutonymph, adult male and adult female at 7 days post-treatment varied between 2.50-4.50%, 46.45-97.86%, 30.69-96.04%, 41.74-92.41%, 92.03-100.00% and 46.28-93.32%, respectively. All of the bacterial supernatants showed a very low effect on the egg period and no statistical difference was found among them. Xenorhabdus szentirmaii and X. nematophila caused more than 90% mortality rate on the mobile stages of T. urticae and they showed the highest efficacy when compared to other bacterial supernatants. As a result of the pot experiments, supernatants of X. szentirmaii, X. nematophila and X. szentirmaii + X. nematophila combine application significantly reduced the T. urticae population. As a result, X. szentirmaii and X. nematophila supernatants could be used as potential control agents against T. urticae.