Effectiveness of Repellent Plants for Controlling Potato Tuber Moth (Symmetrischema tangolias) in the Andean Highlands

Postharvest losses from potato tuber moth severely constrain seed quality in Andean smallholder systems. This study evaluated four locally available repellent plants-<i>Ambrosia peruviana</i>, <i>Eucalyptus globulus</i>, <i>Artemisia absinthium</i>, and <i>Minthostachys mollis</i>-applied as dried leaves layered within seed bags of INIA 302 'Amarilis' under farmer-like storage at two highland sites in Cajamarca, Peru (Huaytorco, 3350 m; Samaday, 2750 m), over 187 days. Within each site, a Completely Randomized Design with three bag-level replicates per treatment was used, and damage was assessed after 187 days as incidence of attacked tubers, internal damage severity and live larval counts. Endpoint data were analyzed separately by site using Kruskal-Wallis tests followed by Dunn's post hoc test with Šidák correction (α = 0.05). Across both sites, all botanicals significantly reduced damage severity and live larval counts relative to the untreated control. At the warmer, lower site, <i>A. absinthium</i> and <i>M. verticillata</i> achieved large effect sizes, with severity and larval numbers reduced by roughly 80-90% compared with the control, while at the cooler, higher site, larvae were not detected in any botanical treatment. These findings indicate that simple layering of dried leaves from locally available plants, particularly wormwood and muña, can substantially mitigate <i>S. tangolias</i> damage in highland seed potato stores and represents a promising, low-cost complement to integrated pest management, although multi-season and dose-response studies are still needed to confirm and refine this approach.