Using herbivore-induced plant volatiles to attract lacewings, hoverflies and parasitoid wasps in vineyards: achievements and constraints

Plants produce volatile organic compounds (VOCs) as an adaptive response to abiotic and biotic stresses. The feeding behaviour of phytophagous arthropods can elicit the production of VOCs in the plant that can be used by predators and parasitoids to locate their prey. These VOCs have been classified as herbivore induced plant volatiles (HIPVs), which are considered highly-detectable synomones helping natural enemies to locate the host habitat. In two vineyards in Tuscany (Central Italy) we tested the attractiveness of sticky traps baited with two synthetic HIPV blends shown previously to be attractive to insect predators (Chrysopidae and Syrphidae) and parasitoids (Braconidae and Ichneumonidae). We also used Malaise traps to investigate the presence of the target insects in the studied areas. White sticky traps baited with a blend of methyl salicylate, acetic acid and 2-phenylethanol were strongly attractive to adult lacewings (Chrysopidae) of the genus Chrysoperla, but not to lacewings of the genus Pseudomallada. On the other hand, yellow sticky traps baited with a blend of geraniol and 2-phenylethanol were not attractive to Syrphidae. Both blends captured a relatively small number of Ichnemonoidea. The effective use of HIPVs to attract lacewings, hoverflies and parasitoid wasps in the field is discussed, focussing on existing constraints and possible future developments