Aphidophagous hoverflies reduce foxglove aphid infestations and improve seed set and fruit yield in sweet pepper

BACKGROUND Larvae of many hoverfly species prey upon aphids, whereas the adults, by relying on nectar and pollen, contribute to the pollination of many plant species. Despite their great potential for pest control and pollination, important gaps still exist regarding the efficacy of hoverflies in regulating infestations of major aphid pests in augmentative biological control programs. Here, we tested the potential of the commercially available hoverflies Eupeodes corollae and Sphaerophoria rueppellii to regulate populations of the foxglove aphid Aulacorthum solani in sweet pepper. RESULTS In a semi‐field experiment, aphid numbers were 93.2% and 78.4% lower in the E. corollae and S. rueppellii treatments, respectively, compared to the control. Fruit yield was increased by 390% and 361% and seed set by 395% and 399% for E. corollae and S. rueppellii. In a separate laboratory trial, we found that under conditions of limited prey, hoverfly larvae did not complete development, but that larvae of S. rueppellii survived significantly longer than larvae of E. corollae. CONCLUSION We have shown for the first time that E. corollae and S. rueppellii can reduce infestations of foxglove aphid in sweet pepper. The limited amount of prey, related to the small size of the A. solani colonies, means that hoverfly larvae were often not able to complete development. In practice, repeated releases of hoverflies, possibly in combination with other natural enemies, might be used to achieve effective suppression of A. solani infestations. © 2021 Society of Chemical Industry We have shown for first time that Eupeodes corollae and Sphaerophoria rueppellii significantly reduced infestations of the foxglove aphid A. solani in sweet pepper. Both hoverfly species significantly increased the fruit yield and seed set through aphid control and likely also through a contribution to pollination. For both hoverfly species, the amount of food available during larval development had a significant impact on the percentage of larvae reaching pupal or adult stages. Under conditions of limited amount of prey and starvation, none of the hoverfly species completed development. However, the larvae of S. rueppellii lived significantly longer compared to the larvae of E. corollae. Given the small size of the A. solani colonies, recurring releases of hoverflies and/or their combined releases with other natural enemies is required for effective suppression of infestations. All together, these results are