Aphid-parasitoid interactions and their contribution to biological control in medicinal Cannabis sativa L. crops.

Abstract

Background: The rapid expansion of medicinal Cannabis sativa L. cultivation contrasts with limited knowledge of its aphid pests and the contribution of parasitoids to their biological control. Quantitative studies evaluating aphid-parasitoid networks in Cannabis under cultivation conditions are scarce. This study characterized aphid-parasitoid interactions in Cannabis grown in households in Argentina over two consecutive cropping seasons.

Results: Weekly sampling of 101 chemotype III Cannabidiol (CBD-dominant) plants across 20 households (2020-2021 and 2021-2022) recorded five aphid and five parasitoid species. A total of nine and twelve aphid-parasitoid interactions were recorded in the first and second seasons, respectively, and 90.5% of collected mummies yielded primary parasitoids. In the second season, the network exhibited higher connectedness (0.65) and modularity (0.104), and lower nestedness (4.45), indicating increased compartmentalization. Interactions involving Aphis fabae and Aphis gossypii with Lysiphlebus testaceipes, Aphidius matricaria, and Aphidius avenae showed high temporal constancy (≥77%) and spatial ubiquity (≥90%). Parasitism varied significantly between phenophases (χ² = 23.7; P < 0.001), with A. gossypii reaching 52.8% during the vegetative stage and 42.9% during flowering. L. testaceipes accounted for 72% of parasitism (N = 5564 mummies). Most parasitoid emergence occurred during flowering, when 69.5% of all parasitoids were redorded.

Conclusion: Aphid-parasitoid networks in medicinal Cannabis were functionally structured and temporally consistent across seasons. L. testaceipes emerged as the dominant and most stable parasitoid, supporting its key role in natural aphid regulation. These findings provide a basis for conservation biological control strategies in emerging Cannabis production systems. © 2026 Society of Chemical Industry.