Management of the devastating pest of potato Phthorimaea operculella Zeller ( Lepidoptera: Gelechiidae ) through oviposition deterrent

BACKGROUND: The potato tuber moth (PTM), Phthorimaea operculella, is a major global pest threatening potato production. Wild potato species, possessing rich genetic diversity and valuable resistance traits, serve as a crucial genetic reservoir for improving cultivated varieties. RESULTS: This study aimed to identify specific wild potato volatiles that mediate host-plant resistance by deterring oviposition in P. operculella. Oviposition cage assays revealed significantly lower egg deposition on wild species leaves compared to susceptible cultivated varieties. These results indicated that the pest had oviposition preference for the cultivated potato varieties, or the wild potato varieties may emit volatiles that deter gravid females, thus influencing oviposition selection. Comparative gas chromatography-mass spectrometry (GC-MS) analysis identified nine volatiles that were either specific to or elevated in wild potato varieties. Significant dose-dependent electroantennogram (EAG) responses from gravid moths were recorded for five of these compounds: benzaldehyde, acetic acid, propanoic acid, γ-terpinene, and (E)-2-hexenal. In subsequent behavioral assays, olfactory repellence in a four-arm olfactometer was induced by benzaldehyde (from 10 μg) and γ-terpinene (from 100 μg), whereas (E)-2-hexenal was effective only at the highest tested dose (1000 μg). In parallel oviposition preference tests, both benzaldehyde and γ-terpinene significantly deterred egg-laying at a lower dose of 10 μg, whereas (E)-2-hexenal required 1000 μg to achieve a similar inhibitory effect. CONCLUSION: These findings provide experimental evidence and a theoretical basis for subsequent research on insect chemical communication and demonstrate the potential of these compounds for developing ecology-based strategies in integrated PTM management.