Field-testing of synthetic herbivore-induced plant volatiles as attractants for beneficial insects.

Seven synthetic herbivore-induced plant volatiles (HIPVs) and a mixture of nonanal + (Z)-3-hexen-1-ol were field tested for their ability to attract beneficial insects in an open cotton field. Eleven species of the main natural enemies of insect pests in cotton fields were studied. Significantly greater numbers of the ladybird beetle Coccinella septempunctata were trapped on (Z)-3-hexenyl acetate-baited cards than on others that were HIPV baited or the control cards. Erigonidium graminicolum was attracted to traps baited with nonanal, (Z)-3-hexenyl acetate, and methyl salicylate (MeSA). The predatory bug Deraeocoris punctulatus was only attracted to traps baited with octanal. The predatory bug Orius similis responded to traps baited with 3,7-dimethyl,1,3,6-octatriene, nonanal, (Z)-3-hexenyl acetate, nonanal + (Z)-3-hexen-1-ol, and MeSA. Dimethyl octatriene, nonanal + (Z)-3-hexen-1-ol, and octanal significantly attracted the syrphid fly Paragus quadrifasciatus. The ladybird beetle Propylaea japonica, the green lacewing Chrysopa sinica, the bigeyed bug Geocoris pallidipennis, the syrphid fly Epistrophe balteata, and the parasitic wasp Campoletis chlorideae did not respond to any of the HIPVs tested. These results are discussed with regard to the potential of HIPVs as tools for recruiting natural enemies into cotton fields.