Field evaluation of the 'attract and reward' biological control approach in vineyards

Herbivore plant damage induces emissions of semiochemicals termedherbivore-induced plant volatiles (HIPVs). These volatile cues can attract thenatural enemies of the attacking herbivores and protect the plant from furtherdamage. Synthetic HIPV application to various crops has also been shownto attract natural enemies. In the present study, nectar plant rewards werecombined with HIPVs in an 'attract and reward' approach. This combinationmight attract natural enemies into treated crops and provide them with foodand shelter to maximise their survival and residency leading to increasedparasitism and lower pest abundance. Trap catches of predators and scelionidparasitoids in treated grapevines were increased by methyl salicylate (MeSA)and methyl anthranilate (MeA) for 1 day and up to 5 days, respectively.The number of herbivorous thrips was also increased for up to 3 days posttreatment.Buckwheat (Fagopyrum esculentum) reward increased catches ofeulophid parasitoids and thrips over the 28-day experiment. These resultssuggest that 'attract' and 'reward' can separately enhance local abundance ofnatural enemies but further work is required to fully realise the potential forsynergistic effects.