Olfactory response of the predatory mirid bug, Macrolophus caliginosus (Het.: Miridae) to clean and infested green bean with two-spotted spider mite and identification of their volatile compounds by using GC-MS technique

Herbivore induced plant volatiles (HIPVs) can be produced by herbivores attack that affects on ecology and behavioural responses of natural enemies. Damaged plant attracts natural enemies due to change the volatile compounds constitute by an active biochemical processes. This study was conducted to test whether green bean HIPVs, as well as odours emitted directly from spider mites influenced the orientation behaviour of the predatory mirid bug, Macrolophus caliginosus Wagner. A Y-tube olfactometer was used to determine the attraction of the predator to herbivore induced volatiles from Tetranychus urticae Koch infested green bean plants over clean plants and to direct prey odours over clean air. The mirid bugs showed a stronger response to odours from infested plants than to those from clean plants. The mirids, however, did not seem to exploit odours emitted directly from the preys themselves. Compounds of infested and uninfested plant volatile blends were also determined by gas chromatography-mass spectrometry (GC-MS). Of a total of 36 infested green bean compounds, 29 compounds are emitted either by uninfested green bean. The results from GC-MS analysis confirm that volatile blends emanate from bean infested by spider mites is different to clean bean and the attractiveness of predatory mirid bugs to infested plant over clean bean is probably resulting in these differences.