Can functional plants support the green lacewing and the 14-spotted ladybird beetle to enhance the biological control of Myzus persicae in protected sweet pepper crops?

Abstract: Functional plants are increasingly recognised as a sustainable strategy for
conservation biological control in greenhouse crops. However, their potential to enhance the
establishment and performance of key aphid predators, and the resulting impact on pest
suppression, remains poorly understood. This study evaluates the effect of functional plant
islands on the establishment of the green lacewing Chrysoperla carnea (Neuroptera:
Chrysopidae) and the 14-spotted ladybird Propylea quatuordecimpunctata (Coleoptera:
Coccinellidae) in sweet pepper, and their subsequent control of the green peach aphid Myzus
persicae (Hemiptera: Aphididae). Functional plant species were selected for their potential to
provide floral resources, shelter, oviposition sites and alternative prey, and were evaluated for
their ability to support the longevity, reproduction and immature development of both predator species. Four treatments will be compared in walk-in cage experiments: (i) a control without functional plants, (ii) Lobularia maritima, (iii) L. maritima + Fagopyrum esculentum + Tagetes kolibri + Verbena × hybrida, and (iv) L. maritima + T. kolibri + F. esculentum + Borago officinalis + Plantago lanceolata + Sorghum spp. + V. × hybrida. The functional plants will be arranged in planters to create functional plant islands within the crop. To determine the value of increasing plant diversity, predator establishment will be assessed by monitoring all life stages of C. carnea and P. quatuordecimpunctata throughout the crop cycle. Following aphid infestation, populations of M. persicae will be monitored to quantify biological control, and sweet pepper yield will be measured at the end of the experiment. The study will provide new insights into the role of functional plant islands in strengthening conservation biological control in greenhouse sweet pepper and their potential to reduce reliance on insecticides.