Terpenes from herbivore-induced tomatoplant volatiles attractNesidiocoris tenuis(Hemiptera: Miridae), a predator of majortomato pests

BACKGROUND: Biological control plays a key role in reducing crop damage byTuta absoluta(Meyrick) andTrialeurodes vapor-ariorum(Westwood), which cause huge yield losses in tomato (Solanum lycopersicumL.). The mirid predatorNesidiocoris tenuis(Reuter) preys heavily on these pests, with satisfying control levels in tomato greenhouses. AlthoughN. tenuisis known to beattracted to volatiles of tomato plants infested byT. absolutaand whitefly, little is known about the specific attractive com-pounds and the effect of prey density on the predator response.RESULTS: Y-tube olfactometer bioassays revealed that the attraction ofN. tenuisto tomato volatiles was positively correlatedwith the density ofT. absolutainfestation, unlikeT. vaporarioruminfestation. The predator was also attracted to volatiles ofT. absolutalarval frass, but not toT. vaporariorumhoneydew orT. absolutasex pheromone. Among the herbivore-induced plantvolatiles (HIPVs) that characterised the attractive plants infested with 20T. absolutalarvae, olfactometer bioassays revealedthatN. tenuisis attracted to the monoterpenes⊍-pinene,⊍-phellandrene, 3-carene,⊎-phellandrene and⊎-ocimene, whereas(E)-⊎-caryophyllene was found to repel the predator. In dose–response bioassays, thefive-component blend of the attractantselicited a relatively low attraction in the predator, and removal of⊎-phellandrene from the blend enhanced the attraction of thepredator to the resulting four-component blend, suggesting synergism among four monoterpenes.CONCLUSION: Thesefindings suggest that a four-component blend of⊍-pinene,⊍-phellandrene, 3-carene and⊎-ocimene couldbe used as a kairomone-based lure to recruit the predator for the biological control ofT. absolutaandT. vaporariorum.