Synthetic herbivore-induced plant volatiles enhance host localization and Parasitization by Bracon brevicornis

Parasitoid wasps are effective biocontrol agents that rely on herbivore-induced plant volatiles (HIPVs) to locate their host insects. HIPVs are complex mixtures of organic compounds, but not all compounds are equally attractive to parasitoids. This study aimed to identify the key HIPV compounds emitted by Zea mays that attract the generalist parasitoid wasp Bracon brevicornis and to evaluate their potential for sustained release in pest management applications.

The compounds (3E,7E)-4,8,12-trimethyltrideca-1,3,7,11-tetraene (TMTT), (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT), and geranyl acetate (GA) elicited the strongest attraction responses from Bracon brevicornis in olfactometer assays. A mixture of these compounds was more effective than individual components, with a ternary blend at a 1:1:2 ratio (TMTT:DMNT:GA) inducing the highest parasitoid attraction. The minimum effective concentration of this blend (0.2 ng/μL) attracted parasitoids over a distance of 5 m. Sustained-release formulations using kaolinite, alginate beads, and mesoporous silica (MCM-41) extended parasitoid attraction for 15, 21, and 54 h, respectively. In the cage study conducted under laboratory conditions, maize plants supplemented with the synthetic HIPV blend showed significantly higher parasitization of Corcyra cephalonica larvae by B. brevicornis compared with control plants.

These results identify key herbivore-induced plant volatiles that mediate attraction and host localization by Bracon brevicornis. Use of a synthetic HIPV blend, particularly when delivered via sustained-release formulations, increased parasitization. Incorporation of synthetic HIPVs into integrated pest management programs may improve the efficiency and reliability of parasitoid-based biological control. © 2026 Society of Chemical Industry.