Fuelling Natural Enemies: Laboratory Assessment of Sugar Solution on the Longevity of Plutella xylostella and Its Parasitoids From Central Argentina

The provisioning of non‐host food sources, such as nectar, is a key strategy in conservation biological control to enhance the fitness and efficacy of natural enemies. The diamondback moth, Plutella xylostella (L.), a globally significant crucifer pest, is often regulated by a complex of larval parasitoids. However, the role of carbohydrate availability in shaping the longevity of this specific pest–parasitoid system in South America remains unexplored. This study assessed the impact of a 40% w/w 1:1 glucose: fructose sugar solution on the adult longevity of P. xylostella and its four dominant parasitoids in central Argentina: Diadegma leontiniae , Apanteles piceotrichosus , Oomyzus sokolowskii and Siphona sp. The facultative hyperparasitoid Conura pseudofulvovariegata was also evaluated. Survival analyses using Kaplan–Meier curves and Cox proportional hazards models revealed that carbohydrate access significantly increased longevity in all species compared to a water‐only control (starvation condition) (Log‐rank test, p < 0.001 for all). However, the magnitude of the response was species‐specific, with C. pseudofulvovariegata showing the greatest relative benefit and P. xylostella the lowest. Under the sugar solution, C . pseudofulvovariegata achieved an exceptional median longevity of 172 days, significantly outliving all other species (Kruskal–Wallis, p < 0.001). These results demonstrate a shared but unequal dependency on exogenous carbohydrates, with natural enemies—particularly the hyperparasitoid—deriving a disproportionate survivorship advantage. The findings underscore that habitat management providing floral resources can selectively fuel natural enemy populations, potentially improving biological control of P. xylostella by enhancing parasitoid longevity and temporal persistence in the crop environment.