Native, naturalized and commercial predators evaluated for use against Diaphorina citri

Diaphorina citri Kuwayama (Hemiptera: Liviidae), is a key pest of citrus associated with the yet uncurable Huanglongbing (HLB) disease, that is threatening worldwide citrus production. Control of D. citri has hitherto relied on chemical insecticides and on the use of the parasitoid Tamarixia radiata (Waterston) (Hymenoptera: Eulophidae). However, use of insecticides is problematic due to environmental and social issues, especially where D. citri is mostly spread in residential areas, and use of T. radiata has resulted in mixed success. Therefore, there is an urgent need to find sustainable and complementary practices to control this pest. Generalist predators, including green lacewings and coccinellids, have been frequently associated to D. citri in field surveys, yet they have rarely been tested. We have tested the predation capability under laboratory, greenhouse and semi-field conditions, of five predators: the green lacewings Chrysoperla comanche (Banks) and C. rufilabris Burmeister (Neuroptera: Chrysopidae), the coccinellids Diomus pumilio Weise and Rhyzobius lophanthae (Blaisdell) (Coleoptera: Coccinellidae) and the brown lacewing Sympherobius barberi Banks (Neuroptera: Hemerobiidae). All of them were capable of feeding on D. citri and reduce its populations under laboratory conditions, but critical differences emerged in greenhouse and field cages, with some predators (the green lacewings and D. pumilio) being the most effective. We discuss possible ways of utilizing these predators as an additional biological control tool to address current limitations of D. citri control in commercial groves, in residential areas and at the urban-agricultural interface.