Artificially applied plant volatile organic compounds modify the behavior of a pest with no adverse effect on its natural enemies in the field

The use of volatile organic compounds (VOCs) derived from plants to manipulate insect pest behavior can be applied in an integrated pest management strategy (IPM) using a combination of attractive and repulsive stimuli. The “push–pull” strategy was developed on this idea in order to disturb and modify the distribution and abundance of pests to protect crops and reduce the use of agrochemicals. This field experiment investigates, in a “push–pull” context using broccoli as a target crop and Chinese cabbage as a pull component, the stimulo-deterrent effect of five synthetic VOCs (dimethyl disulfide, linalool, geraniol, eucalyptol and citronellol) on the oviposition of the cabbage root fly Delia radicum. With the exception of linalool, all compounds tested had a significant effect in the field and eucalyptol showed the most promising results, reducing oviposition on broccoli by 45 %. Moreover, eucalyptol was the only VOC able to reduce the final infestation of D. radicum, i.e., the number of pupae. The other VOCs reduced oviposition by 20–30 %. No adverse effect of the treatments was found on major parasitoids (Trybliographa rapae and Aleochara bipustulata) and potential predators of D. radicum. This study highlights the potential of VOCs as deterrent stimuli against agricultural pests in the field.