Field evaluation of herbivore-induced plant volatiles as attractants for beneficial insects: methyl salicylate and the green lacewing, Chrysopa nigricornis.

Synthetic methyl salicylate (MeSA), a herbivore-induced plant volatile (HIPV), was demonstrated to be an attractant for the green lacewing, Chrysopa nigricornis, in two field experiments conducted in a Washington hop yard. Significantly greater numbers of C. nigricornis were trapped on MeSA-baited sticky cards (mean: 2.8 +/- 0.4/card/week) than on unbaited cards (0.45 +/- 0.15) during June-September. Cards baited with two other HIPVs, hexenyl acetate and dimethyl nonatriene, did not attract more C. nigricornis than did unbaited traps (0.30 +/- 0.10, 0.44 +/- 0.15, respectively). MeSA-baited Unitraps captured 1.9 +/- 0.5 C. nigricornis/trap/week during July-August compared to 0.20 +/- 0.20/trap/week in methyl eugenol-baited traps and 0.03 +/- 0.03/trap/week in unbaited traps. The potential use of MeSA in enhancing C. nigricornis populations in Washington hop yards as an aid to conservation biological control of aphids and mites is discussed.