The effect of Trichoderma harzianum Tr6 on the interaction between Phytoseiuluspersimilis (Acari: Tetranychidae, Phytoseiidae) and its prey Tetranychus urticae on bean plant

The fungi related to the genus Trichoderma are of important biological control agents that although their direct and indirect effects on insect and mite pests have vastly been studied but less is known about their interactions with host plant and its effects on the predators. Here, we used Tetranychusurticae infested been plant as host, treated with T. harzianum Tr6, in order to investigate bahavioural characteristics of the predatory mite, Phytoseiulus persimilisi.e. the predation, oviposition and establishment rate. Besides, the olfactory response of the predator was studied. Using the paired patches, treated and untreated with Trichoderma, we recorded a higher predation rate of P. persimilis. Conducting the oviposition experiment performed with same-aged bean potted plants, with adhesive banned stems, we recorded no significant difference in the predator oviposition rates between the plants treated and untreated with fungi. In the establishment experiment, performed with connecting the leaf patches with a plastic bridge, the number of predator presence time on fungi treated patches was significantly more than that on control ones. The olfactory experiments were performed considering three starvation status, no starvation, three hours and six hours and two states of T.urticae infestation period (two and four days) and five minutes critical time. None of the treatments showed predator attraction towards plants treated with fungi. The significant increase in the establishment and predation rates on patches treated with fungi is due to the quantitative or qualitative promotion of herbivore induced plant volatiles that needs further investigations regarding the results related to olfactory and oviposition tests.