Evaluation of various predators for controlling the aphid Aphis nerii on ornamental Mandevilla plants

Abstract: The oleander aphid Aphis nerii (Boyer de Fonscolombe) is a major pest of
Mandevilla, a market-expanding ornamental crop belonging to the milkweed Apocynaceae
family. As a specialized pest on some milkweed plants, A. nerii can sequester plant toxic
compounds (cardenolides) and exploit them as defense mechanisms against natural enemies,
making the development of biological control strategies particularly challenging. This study
evaluates the suitability of A. nerii as prey for seven generalist predators, as well as their ability to suppress the aphid population. Tested predators were: Chrysoperla carnea Stephens (Neuroptera: Chrysopidae), Sphaerophoria rueppellii Wiedmann (Diptera: Syrphidae), Episyrphus balteatus DeGeer (Diptera: Syrphidae), Micromus angulatus Stephens (Neuroptera: Hemerobidae), Propylea quatuordecimpunctata L. (Coleoptera: Coccinellidae), Adalia bipunctata L. (Coleoptera: Coccinellidae), and Sympherobius fallax Navas (Neuroptera: Hemerobidae). Then, we assessed the predation rates and the functional response of C. carnea, M. angulatus, and P. quatuordecimpunctata preying on A. nerii. Results showed that M. angulatus, P. quatuordecimpunctata, and S. rueppellii can survive, develop, and reproduce on A. nerii, while this aphid was unsuitable prey for the other predators. Chrysoperla carnea did not show a response to varying densities of A. nerii; in contrast, both M. angulatus and P. quatuordecimpunctata exhibited a Type II functional response highlighting their potential for A. nerii control.