Attraction of Telenomus remus to Egg Volatiles of Spodoptera litura and Oviposition-Induced Plant Volatiles From Tobacco (Nicotiana tabacum)

The tobacco cutworm, Spodoptera litura F. (Lepidoptera: Noctuidae), is a polyphagous pest that causes enormous losses in tobacco production as it develops resistance to pesticides in China. Telenomus remus N. (Hymenoptera: Scelionidae) is an effective egg parasitoid for the genus Spodoptera. However, little is known about the volatile compounds that attract the parasitoid. In the present study, we investigated the response of T. remus to volatiles released from various sources, including Spodoptera litura egg masses, healthy tobacco plants, plants with manually introduced eggs, and plants with natural oviposition. The chemical profiles of the crude extracts were identified using gas chromatography–mass spectrometry (GC–MS), and the behavioral assay was performed using a Y-tube olfactometer. Naïve and experienced T. remus showed significant attraction to crude extracts of S. litura egg masses and to oviposition-induced plant volatiles (OIPVs). In subsequent experiments, different concentrations and combinations of the synthetic volatiles obtained from these crude extracts were tested. Notably, the binary and ternary mixtures showed significant attraction, where the binary combination of linalool (L) with tetracosane (T) and linalool (L) with cis-3-hexenyl acetate (C) was strongly attractive. These results underscore the potential of using synthetic volatile dispensers, particularly binary combinations with precise doses, to enhance retention of T. remus and improve the efficacy of the biological control program.