Leveraging floral resources and natural enemies in organic greenhouse tomatoes to manage the tomato pinworm <i>Tuta absoluta</i>

Abstract BACKGROUND The growing demand for sustainable agriculture has reinforced the central role of integrated pest management (IPM) in organic greenhouse production, particularly for high‐value crops such as tomatoes, which remain highly susceptible to the South American tomato pinworm, Tuta absoluta (Lepidoptera: Gelechiidae). In this study, we investigated the synergistic contributions of flower strips garden cosmos ( Cosmos bipinnatus ; Asterales: Asteraceae) and big marigold ( Tagetes erecta ; Asterales: Asteraceae) together with key natural enemies, including the tomato mirid Nesidiocoris tenuis (Hemiptera: Miridae), the common green lacewing Chrysoperla carnea (Neuroptera: Chrysopidae), and the egg parasitoid Trichogramma chilonis (Hymenoptera: Trichogrammatidae), toward suppressing T. absoluta under controlled greenhouse conditions. We evaluated the factorial combinations of two flower species (cosmos and marigold), two flower statuses (present or absent), and three natural enemy species (2 × 2 × 3 = 12 treatment combinations). At the start of the experiment, 10 tomato plants per plot were randomly selected and tagged. The same plants were assessed weekly for damage, natural enemy abundance, and fecundity. RESULTS T. absoluta damage was significantly reduced by use of the flower strips, the garden cosmos being the most effective by 10–15% in reducing the damage due to its extended and more consistent bloom time, which improved natural enemy retention and performance. Damage was higher in all the non‐floral controls. The natural enemy population density (per plant) and fecundity also showed significant increases in floral treatments, and cosmos and N. tenuis provided the highest suppression. Parasitism by T. chilonis was also higher in the flowers and positively correlated with the flower intensity. CONCLUSION The results of this study indicate that habitat manipulation can be used as a powerful tool to help strengthen biological control in organic greenhouse systems, minimizing the use of chemical inputs. Our results provide actionable knowledge to improve the use of IPM in greenhouse tomato production due to the critical knowledge gaps between functional interactions of floral resources and natural enemies. Future work should include multi‐year trials that will help better understand mechanisms and enable more widespread adoption of these practices. © 2026 Society of Chemical Industry.